Exemple #1
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.  Labels are a
    sequence of strings and loc can be a string or an integer
    specifying the legend location

    The location codes are::

      'best'         : 0, (only implemented for axis legends)
      'upper right'  : 1,
      'upper left'   : 2,
      'lower left'   : 3,
      'lower right'  : 4,
      'right'        : 5,
      'center left'  : 6,
      'center right' : 7,
      'lower center' : 8,
      'upper center' : 9,
      'center'       : 10,

    loc can be a tuple of the normalized coordinate values with
    respect its parent.

    """
    codes = {
        'best': 0,  # only implemented for axis legends
        'upper right': 1,
        'upper left': 2,
        'lower left': 3,
        'lower right': 4,
        'right': 5,
        'center left': 6,
        'center right': 7,
        'lower center': 8,
        'upper center': 9,
        'center': 10,
    }

    zorder = 5

    def __str__(self):
        return "Legend"

    def __init__(
        self,
        parent,
        handles,
        labels,
        loc=None,
        numpoints=None,  # the number of points in the legend line
        markerscale=None,  # the relative size of legend markers
        # vs. original
        markerfirst=True,  # controls ordering (left-to-right) of
        # legend marker and label
        scatterpoints=None,  # number of scatter points
        scatteryoffsets=None,
        prop=None,  # properties for the legend texts
        fontsize=None,  # keyword to set font size directly

        # spacing & pad defined as a fraction of the font-size
        borderpad=None,  # the whitespace inside the legend border
        labelspacing=None,  # the vertical space between the legend
        # entries
        handlelength=None,  # the length of the legend handles
        handleheight=None,  # the height of the legend handles
        handletextpad=None,  # the pad between the legend handle
        # and text
        borderaxespad=None,  # the pad between the axes and legend
        # border
        columnspacing=None,  # spacing between columns
        ncol=1,  # number of columns
        mode=None,  # mode for horizontal distribution of columns.
        # None, "expand"
        fancybox=None,  # True use a fancy box, false use a rounded
        # box, none use rc
        shadow=None,
        title=None,  # set a title for the legend
        framealpha=None,  # set frame alpha
        bbox_to_anchor=None,  # bbox that the legend will be anchored.
        bbox_transform=None,  # transform for the bbox
        frameon=None,  # draw frame
        handler_map=None,
    ):
        """
        - *parent*: the artist that contains the legend
        - *handles*: a list of artists (lines, patches) to be added to the
                      legend
        - *labels*: a list of strings to label the legend

        Optional keyword arguments:

        ================   ====================================================
        Keyword            Description
        ================   ====================================================
        loc                a location code
        prop               the font property
        fontsize           the font size (used only if prop is not specified)
        markerscale        the relative size of legend markers vs. original
        markerfirst        If true, place legend marker to left of label
                           If false, place legend marker to right of label
        numpoints          the number of points in the legend for line
        scatterpoints      the number of points in the legend for scatter plot
        scatteryoffsets    a list of yoffsets for scatter symbols in legend
        frameon            if True, draw a frame around the legend.
                           If None, use rc
        fancybox           if True, draw a frame with a round fancybox.
                           If None, use rc
        shadow             if True, draw a shadow behind legend
        framealpha         If not None, alpha channel for the frame.
        ncol               number of columns
        borderpad          the fractional whitespace inside the legend border
        labelspacing       the vertical space between the legend entries
        handlelength       the length of the legend handles
        handleheight       the height of the legend handles
        handletextpad      the pad between the legend handle and text
        borderaxespad      the pad between the axes and legend border
        columnspacing      the spacing between columns
        title              the legend title
        bbox_to_anchor     the bbox that the legend will be anchored.
        bbox_transform     the transform for the bbox. transAxes if None.
        ================   ====================================================


        The pad and spacing parameters are measured in font-size units.  e.g.,
        a fontsize of 10 points and a handlelength=5 implies a handlelength of
        50 points.  Values from rcParams will be used if None.

        Users can specify any arbitrary location for the legend using the
        *bbox_to_anchor* keyword argument. bbox_to_anchor can be an instance
        of BboxBase(or its derivatives) or a tuple of 2 or 4 floats.
        See :meth:`set_bbox_to_anchor` for more detail.

        The legend location can be specified by setting *loc* with a tuple of
        2 floats, which is interpreted as the lower-left corner of the legend
        in the normalized axes coordinate.
        """
        # local import only to avoid circularity
        from matplotlib.axes import Axes
        from matplotlib.figure import Figure

        Artist.__init__(self)

        if prop is None:
            if fontsize is not None:
                self.prop = FontProperties(size=fontsize)
            else:
                self.prop = FontProperties(size=rcParams["legend.fontsize"])
        elif isinstance(prop, dict):
            self.prop = FontProperties(**prop)
            if "size" not in prop:
                self.prop.set_size(rcParams["legend.fontsize"])
        else:
            self.prop = prop

        self._fontsize = self.prop.get_size_in_points()

        self.texts = []
        self.legendHandles = []
        self._legend_title_box = None

        #: A dictionary with the extra handler mappings for this Legend
        #: instance.
        self._custom_handler_map = handler_map

        locals_view = locals()
        for name in [
                "numpoints", "markerscale", "shadow", "columnspacing",
                "scatterpoints", "handleheight", 'borderpad', 'labelspacing',
                'handlelength', 'handletextpad', 'borderaxespad'
        ]:
            if locals_view[name] is None:
                value = rcParams["legend." + name]
            else:
                value = locals_view[name]
            setattr(self, name, value)
        del locals_view

        handles = list(handles)
        if len(handles) < 2:
            ncol = 1
        self._ncol = ncol

        if self.numpoints <= 0:
            raise ValueError("numpoints must be > 0; it was %d" % numpoints)

        # introduce y-offset for handles of the scatter plot
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3. / 8., 4. / 8., 2.5 / 8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps = int(self.scatterpoints / len(self._scatteryoffsets)) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets,
                                        reps)[:self.scatterpoints]

        # _legend_box is an OffsetBox instance that contains all
        # legend items and will be initialized from _init_legend_box()
        # method.
        self._legend_box = None

        if isinstance(parent, Axes):
            self.isaxes = True
            self.axes = parent
            self.set_figure(parent.figure)
        elif isinstance(parent, Figure):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError("Legend needs either Axes or Figure as parent")
        self.parent = parent

        if loc is None:
            loc = rcParams["legend.loc"]
            if not self.isaxes and loc in [0, 'best']:
                loc = 'upper right'
        if is_string_like(loc):
            if loc not in self.codes:
                if self.isaxes:
                    warnings.warn('Unrecognized location "%s". Falling back '
                                  'on "best"; valid locations are\n\t%s\n' %
                                  (loc, '\n\t'.join(six.iterkeys(self.codes))))
                    loc = 0
                else:
                    warnings.warn('Unrecognized location "%s". Falling back '
                                  'on "upper right"; '
                                  'valid locations are\n\t%s\n' %
                                  (loc, '\n\t'.join(six.iterkeys(self.codes))))
                    loc = 1
            else:
                loc = self.codes[loc]
        if not self.isaxes and loc == 0:
            warnings.warn('Automatic legend placement (loc="best") not '
                          'implemented for figure legend. '
                          'Falling back on "upper right".')
            loc = 1

        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

        # We use FancyBboxPatch to draw a legend frame. The location
        # and size of the box will be updated during the drawing time.

        self.legendPatch = FancyBboxPatch(xy=(0.0, 0.0),
                                          width=1.,
                                          height=1.,
                                          facecolor=rcParams["axes.facecolor"],
                                          edgecolor=rcParams["axes.edgecolor"],
                                          mutation_scale=self._fontsize,
                                          snap=True)

        # The width and height of the legendPatch will be set (in the
        # draw()) to the length that includes the padding. Thus we set
        # pad=0 here.
        if fancybox is None:
            fancybox = rcParams["legend.fancybox"]

        if fancybox:
            self.legendPatch.set_boxstyle("round", pad=0, rounding_size=0.2)
        else:
            self.legendPatch.set_boxstyle("square", pad=0)

        self._set_artist_props(self.legendPatch)

        self._drawFrame = frameon
        if frameon is None:
            self._drawFrame = rcParams["legend.frameon"]

        # init with null renderer
        self._init_legend_box(handles, labels, markerfirst)

        if framealpha is None:
            self.get_frame().set_alpha(rcParams["legend.framealpha"])
        else:
            self.get_frame().set_alpha(framealpha)

        self._loc = loc
        self.set_title(title)
        self._last_fontsize_points = self._fontsize
        self._draggable = None

    def _set_artist_props(self, a):
        """
        set the boilerplate props for artists added to axes
        """
        a.set_figure(self.figure)
        if self.isaxes:
            # a.set_axes(self.axes)
            a.axes = self.axes

        a.set_transform(self.get_transform())

    def _set_loc(self, loc):
        # find_offset function will be provided to _legend_box and
        # _legend_box will draw itself at the location of the return
        # value of the find_offset.
        self._loc_real = loc
        if loc == 0:
            _findoffset = self._findoffset_best
        else:
            _findoffset = self._findoffset_loc

#       def findoffset(width, height, xdescent, ydescent):
#           return _findoffset(width, height, xdescent, ydescent, renderer)

        self._legend_box.set_offset(_findoffset)

        self._loc_real = loc

    def _get_loc(self):
        return self._loc_real

    _loc = property(_get_loc, _set_loc)

    def _findoffset_best(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend at its best position"
        ox, oy = self._find_best_position(width, height, renderer)
        return ox + xdescent, oy + ydescent

    def _findoffset_loc(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend using the location code"

        if iterable(self._loc) and len(self._loc) == 2:
            # when loc is a tuple of axes(or figure) coordinates.
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy
        else:
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox,
                                           self.get_bbox_to_anchor(), renderer)

        return x + xdescent, y + ydescent

    @allow_rasterization
    def draw(self, renderer):
        "Draw everything that belongs to the legend"
        if not self.get_visible():
            return

        renderer.open_group('legend')

        fontsize = renderer.points_to_pixels(self._fontsize)

        # if mode == fill, set the width of the legend_box to the
        # width of the paret (minus pads)
        if self._mode in ["expand"]:
            pad = 2 * (self.borderaxespad + self.borderpad) * fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width - pad)

        # update the location and size of the legend. This needs to
        # be done in any case to clip the figure right.
        bbox = self._legend_box.get_window_extent(renderer)
        self.legendPatch.set_bounds(bbox.x0, bbox.y0, bbox.width, bbox.height)
        self.legendPatch.set_mutation_scale(fontsize)

        if self._drawFrame:
            if self.shadow:
                shadow = Shadow(self.legendPatch, 2, -2)
                shadow.draw(renderer)

            self.legendPatch.draw(renderer)

        self._legend_box.draw(renderer)

        renderer.close_group('legend')

    def _approx_text_height(self, renderer=None):
        """
        Return the approximate height of the text. This is used to place
        the legend handle.
        """
        if renderer is None:
            return self._fontsize
        else:
            return renderer.points_to_pixels(self._fontsize)

    # _default_handler_map defines the default mapping between plot
    # elements and the legend handlers.

    _default_handler_map = {
        StemContainer:
        legend_handler.HandlerStem(),
        ErrorbarContainer:
        legend_handler.HandlerErrorbar(),
        Line2D:
        legend_handler.HandlerLine2D(),
        Patch:
        legend_handler.HandlerPatch(),
        LineCollection:
        legend_handler.HandlerLineCollection(),
        RegularPolyCollection:
        legend_handler.HandlerRegularPolyCollection(),
        CircleCollection:
        legend_handler.HandlerCircleCollection(),
        BarContainer:
        legend_handler.HandlerPatch(
            update_func=legend_handler.update_from_first_child),
        tuple:
        legend_handler.HandlerTuple(),
        PathCollection:
        legend_handler.HandlerPathCollection(),
        PolyCollection:
        legend_handler.HandlerPolyCollection()
    }

    # (get|set|update)_default_handler_maps are public interfaces to
    # modify the default handler map.

    @classmethod
    def get_default_handler_map(cls):
        """
        A class method that returns the default handler map.
        """
        return cls._default_handler_map

    @classmethod
    def set_default_handler_map(cls, handler_map):
        """
        A class method to set the default handler map.
        """
        cls._default_handler_map = handler_map

    @classmethod
    def update_default_handler_map(cls, handler_map):
        """
        A class method to update the default handler map.
        """
        cls._default_handler_map.update(handler_map)

    def get_legend_handler_map(self):
        """
        return the handler map.
        """

        default_handler_map = self.get_default_handler_map()

        if self._custom_handler_map:
            hm = default_handler_map.copy()
            hm.update(self._custom_handler_map)
            return hm
        else:
            return default_handler_map

    @staticmethod
    def get_legend_handler(legend_handler_map, orig_handle):
        """
        return a legend handler from *legend_handler_map* that
        corresponds to *orig_handler*.

        *legend_handler_map* should be a dictionary object (that is
        returned by the get_legend_handler_map method).

        It first checks if the *orig_handle* itself is a key in the
        *legend_hanler_map* and return the associated value.
        Otherwise, it checks for each of the classes in its
        method-resolution-order. If no matching key is found, it
        returns None.
        """
        legend_handler_keys = list(six.iterkeys(legend_handler_map))
        if orig_handle in legend_handler_keys:
            handler = legend_handler_map[orig_handle]
        else:

            for handle_type in type(orig_handle).mro():
                if handle_type in legend_handler_map:
                    handler = legend_handler_map[handle_type]
                    break
            else:
                handler = None

        return handler

    def _init_legend_box(self, handles, labels, markerfirst=True):
        """
        Initialize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """

        fontsize = self._fontsize

        # legend_box is a HPacker, horizontally packed with
        # columns. Each column is a VPacker, vertically packed with
        # legend items. Each legend item is HPacker packed with
        # legend handleBox and labelBox. handleBox is an instance of
        # offsetbox.DrawingArea which contains legend handle. labelBox
        # is an instance of offsetbox.TextArea which contains legend
        # text.

        text_list = []  # the list of text instances
        handle_list = []  # the list of text instances

        label_prop = dict(
            verticalalignment='baseline',
            horizontalalignment='left',
            fontproperties=self.prop,
        )

        labelboxes = []
        handleboxes = []

        # The approximate height and descent of text. These values are
        # only used for plotting the legend handle.
        descent = 0.35 * self._approx_text_height() * (self.handleheight - 0.7)
        # 0.35 and 0.7 are just heuristic numbers and may need to be improved.
        height = self._approx_text_height() * self.handleheight - descent
        # each handle needs to be drawn inside a box of (x, y, w, h) =
        # (0, -descent, width, height).  And their coordinates should
        # be given in the display coordinates.

        # The transformation of each handle will be automatically set
        # to self.get_trasnform(). If the artist does not use its
        # default transform (e.g., Collections), you need to
        # manually set their transform to the self.get_transform().
        legend_handler_map = self.get_legend_handler_map()

        for orig_handle, lab in zip(handles, labels):
            handler = self.get_legend_handler(legend_handler_map, orig_handle)
            if handler is None:
                warnings.warn(
                    "Legend does not support {!r} instances.\nA proxy artist "
                    "may be used instead.\nSee: "
                    "http://matplotlib.org/users/legend_guide.html"
                    "#using-proxy-artist".format(orig_handle))
                # We don't have a handle for this artist, so we just defer
                # to None.
                handle_list.append(None)
            else:
                textbox = TextArea(lab,
                                   textprops=label_prop,
                                   multilinebaseline=True,
                                   minimumdescent=True)
                text_list.append(textbox._text)

                labelboxes.append(textbox)

                handlebox = DrawingArea(width=self.handlelength * fontsize,
                                        height=height,
                                        xdescent=0.,
                                        ydescent=descent)
                handleboxes.append(handlebox)

                # Create the artist for the legend which represents the
                # original artist/handle.
                handle_list.append(
                    handler.legend_artist(self, orig_handle, fontsize,
                                          handlebox))

        if len(handleboxes) > 0:

            # We calculate number of rows in each column. The first
            # (num_largecol) columns will have (nrows+1) rows, and remaining
            # (num_smallcol) columns will have (nrows) rows.
            ncol = min(self._ncol, len(handleboxes))
            nrows, num_largecol = divmod(len(handleboxes), ncol)
            num_smallcol = ncol - num_largecol

            # starting index of each column and number of rows in it.
            largecol = safezip(
                list(xrange(0, num_largecol * (nrows + 1), (nrows + 1))),
                [nrows + 1] * num_largecol)
            smallcol = safezip(
                list(
                    xrange(num_largecol * (nrows + 1), len(handleboxes),
                           nrows)), [nrows] * num_smallcol)
        else:
            largecol, smallcol = [], []

        handle_label = safezip(handleboxes, labelboxes)
        columnbox = []
        for i0, di in largecol + smallcol:
            # pack handleBox and labelBox into itemBox
            itemBoxes = [
                HPacker(pad=0,
                        sep=self.handletextpad * fontsize,
                        children=[h, t] if markerfirst else [t, h],
                        align="baseline") for h, t in handle_label[i0:i0 + di]
            ]
            # minimumdescent=False for the text of the last row of the column
            if markerfirst:
                itemBoxes[-1].get_children()[1].set_minimumdescent(False)
            else:
                itemBoxes[-1].get_children()[0].set_minimumdescent(False)

            # pack columnBox
            if markerfirst:
                alignment = "baseline"
            else:
                alignment = "right"
            columnbox.append(
                VPacker(pad=0,
                        sep=self.labelspacing * fontsize,
                        align=alignment,
                        children=itemBoxes))

        if self._mode == "expand":
            mode = "expand"
        else:
            mode = "fixed"

        sep = self.columnspacing * fontsize
        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep,
                                          align="baseline",
                                          mode=mode,
                                          children=columnbox)
        self._legend_title_box = TextArea("")
        self._legend_box = VPacker(
            pad=self.borderpad * fontsize,
            sep=self.labelspacing * fontsize,
            align="center",
            children=[self._legend_title_box, self._legend_handle_box])
        self._legend_box.set_figure(self.figure)
        self.texts = text_list
        self.legendHandles = handle_list

    def _auto_legend_data(self):
        """
        Returns list of vertices and extents covered by the plot.

        Returns a two long list.

        First element is a list of (x, y) vertices (in
        display-coordinates) covered by all the lines and line
        collections, in the legend's handles.

        Second element is a list of bounding boxes for all the patches in
        the legend's handles.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        ax = self.parent
        bboxes = []
        lines = []

        for handle in ax.lines:
            assert isinstance(handle, Line2D)
            path = handle.get_path()
            trans = handle.get_transform()
            tpath = trans.transform_path(path)
            lines.append(tpath)

        for handle in ax.patches:
            assert isinstance(handle, Patch)

            if isinstance(handle, Rectangle):
                transform = handle.get_data_transform()
                bboxes.append(handle.get_bbox().transformed(transform))
            else:
                transform = handle.get_transform()
                bboxes.append(handle.get_path().get_extents(transform))

        try:
            vertices = np.concatenate([l.vertices for l in lines])
        except ValueError:
            vertices = np.array([])

        return [vertices, bboxes, lines]

    def draw_frame(self, b):
        'b is a boolean.  Set draw frame to b'
        self.set_frame_on(b)

    def get_children(self):
        'return a list of child artists'
        children = []
        if self._legend_box:
            children.append(self._legend_box)
        children.append(self.get_frame())

        return children

    def get_frame(self):
        'return the Rectangle instance used to frame the legend'
        return self.legendPatch

    def get_lines(self):
        'return a list of lines.Line2D instances in the legend'
        return [h for h in self.legendHandles if isinstance(h, Line2D)]

    def get_patches(self):
        'return a list of patch instances in the legend'
        return silent_list(
            'Patch', [h for h in self.legendHandles if isinstance(h, Patch)])

    def get_texts(self):
        'return a list of text.Text instance in the legend'
        return silent_list('Text', self.texts)

    def set_title(self, title, prop=None):
        """
        set the legend title. Fontproperties can be optionally set
        with *prop* parameter.
        """
        self._legend_title_box._text.set_text(title)

        if prop is not None:
            if isinstance(prop, dict):
                prop = FontProperties(**prop)
            self._legend_title_box._text.set_fontproperties(prop)

        if title:
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box.set_visible(False)

    def get_title(self):
        'return Text instance for the legend title'
        return self._legend_title_box._text

    def get_window_extent(self, *args, **kwargs):
        'return a extent of the legend'
        return self.legendPatch.get_window_extent(*args, **kwargs)

    def get_frame_on(self):
        """
        Get whether the legend box patch is drawn
        """
        return self._drawFrame

    def set_frame_on(self, b):
        """
        Set whether the legend box patch is drawn

        ACCEPTS: [ *True* | *False* ]
        """
        self._drawFrame = b

    def get_bbox_to_anchor(self):
        """
        return the bbox that the legend will be anchored
        """
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor

    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        set the bbox that the legend will be anchored.

        *bbox* can be a BboxBase instance, a tuple of [left, bottom,
        width, height] in the given transform (normalized axes
        coordinate if None), or a tuple of [left, bottom] where the
        width and height will be assumed to be zero.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError:
                raise ValueError("Invalid argument for bbox : %s" % str(bbox))

            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]

            self._bbox_to_anchor = Bbox.from_bounds(*bbox)

        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)

        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor, transform)

    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x,y) coordinate of the bbox.

        - loc: a location code in range(1, 11).
          This corresponds to the possible values for self._loc, excluding
          "best".

        - bbox: bbox to be placed, display coodinate units.
        - parentbbox: a parent box which will contain the bbox. In
            display coordinates.
        """
        assert loc in range(1, 11)  # called only internally

        BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = list(xrange(11))

        anchor_coefs = {
            UR: "NE",
            UL: "NW",
            LL: "SW",
            LR: "SE",
            R: "E",
            CL: "W",
            CR: "E",
            LC: "S",
            UC: "N",
            C: "C"
        }

        c = anchor_coefs[loc]

        fontsize = renderer.points_to_pixels(self._fontsize)
        container = parentbbox.padded(-(self.borderaxespad) * fontsize)
        anchored_box = bbox.anchored(c, container=container)
        return anchored_box.x0, anchored_box.y0

    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.

        `consider` is a list of (x, y) pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        verts, bboxes, lines = self._auto_legend_data()

        bbox = Bbox.from_bounds(0, 0, width, height)
        if consider is None:
            consider = [
                self._get_anchored_bbox(x, bbox, self.get_bbox_to_anchor(),
                                        renderer)
                for x in range(1, len(self.codes))
            ]

#       tx, ty = self.legendPatch.get_x(), self.legendPatch.get_y()

        candidates = []
        for l, b in consider:
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            # XXX TODO: If markers are present, it would be good to
            # take their into account when checking vertex overlaps in
            # the next line.
            badness = legendBox.count_contains(verts)
            badness += legendBox.count_overlaps(bboxes)
            for line in lines:
                # FIXME: the following line is ill-suited for lines
                # that 'spiral' around the center, because the bbox
                # may intersect with the legend even if the line
                # itself doesn't. One solution would be to break up
                # the line into its straight-segment components, but
                # this may (or may not) result in a significant
                # slowdown if lines with many vertices are present.
                if line.intersects_bbox(legendBox):
                    badness += 1

            ox, oy = l, b
            if badness == 0:
                return ox, oy

            candidates.append((badness, (l, b)))

        # rather than use min() or list.sort(), do this so that we are assured
        # that in the case of two equal badnesses, the one first considered is
        # returned.
        # NOTE: list.sort() is stable.But leave as it is for now. -JJL
        minCandidate = candidates[0]
        for candidate in candidates:
            if candidate[0] < minCandidate[0]:
                minCandidate = candidate

        ox, oy = minCandidate[1]

        return ox, oy

    def contains(self, event):
        return self.legendPatch.contains(event)

    def draggable(self, state=None, use_blit=False, update="loc"):
        """
        Set the draggable state -- if state is

          * None : toggle the current state

          * True : turn draggable on

          * False : turn draggable off

        If draggable is on, you can drag the legend on the canvas with
        the mouse.  The DraggableLegend helper instance is returned if
        draggable is on.

        The update parameter control which parameter of the legend changes
        when dragged. If update is "loc", the *loc* paramter of the legend
        is changed. If "bbox", the *bbox_to_anchor* parameter is changed.
        """
        is_draggable = self._draggable is not None

        # if state is None we'll toggle
        if state is None:
            state = not is_draggable

        if state:
            if self._draggable is None:
                self._draggable = DraggableLegend(self,
                                                  use_blit,
                                                  update=update)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None

        return self._draggable
Exemple #2
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.

    """
    codes = {
        'best': 0,  # only implemented for axes legends
        'upper right': 1,
        'upper left': 2,
        'lower left': 3,
        'lower right': 4,
        'right': 5,
        'center left': 6,
        'center right': 7,
        'lower center': 8,
        'upper center': 9,
        'center': 10,
    }

    zorder = 5

    def __str__(self):
        return "Legend"

    @docstring.dedent_interpd
    def __init__(
        self,
        parent,
        handles,
        labels,
        loc=None,
        numpoints=None,  # the number of points in the legend line
        markerscale=None,  # the relative size of legend markers
        # vs. original
        markerfirst=True,  # controls ordering (left-to-right) of
        # legend marker and label
        scatterpoints=None,  # number of scatter points
        scatteryoffsets=None,
        prop=None,  # properties for the legend texts
        fontsize=None,  # keyword to set font size directly

        # spacing & pad defined as a fraction of the font-size
        borderpad=None,  # the whitespace inside the legend border
        labelspacing=None,  # the vertical space between the legend
        # entries
        handlelength=None,  # the length of the legend handles
        handleheight=None,  # the height of the legend handles
        handletextpad=None,  # the pad between the legend handle
        # and text
        borderaxespad=None,  # the pad between the axes and legend
        # border
        columnspacing=None,  # spacing between columns
        ncol=1,  # number of columns
        mode=None,  # mode for horizontal distribution of columns.
        # None, "expand"
        fancybox=None,  # True use a fancy box, false use a rounded
        # box, none use rc
        shadow=None,
        title=None,  # set a title for the legend
        title_fontsize=None,  # set to ax.fontsize if None
        framealpha=None,  # set frame alpha
        edgecolor=None,  # frame patch edgecolor
        facecolor=None,  # frame patch facecolor
        bbox_to_anchor=None,  # bbox that the legend will be anchored.
        bbox_transform=None,  # transform for the bbox
        frameon=None,  # draw frame
        handler_map=None,
    ):
        """
        Parameters
        ----------
        parent : `~matplotlib.axes.Axes` or `.Figure`
            The artist that contains the legend.

        handles : sequence of `.Artist`
            A list of Artists (lines, patches) to be added to the legend.

        labels : sequence of strings
            A list of labels to show next to the artists. The length of handles
            and labels should be the same. If they are not, they are truncated
            to the smaller of both lengths.

        Other Parameters
        ----------------

        %(_legend_kw_doc)s

        Notes
        -----

        Users can specify any arbitrary location for the legend using the
        *bbox_to_anchor* keyword argument. bbox_to_anchor can be an instance
        of BboxBase(or its derivatives) or a tuple of 2 or 4 floats.
        See :meth:`set_bbox_to_anchor` for more detail.

        The legend location can be specified by setting *loc* with a tuple of
        2 floats, which is interpreted as the lower-left corner of the legend
        in the normalized axes coordinate.
        """
        # local import only to avoid circularity
        from matplotlib.axes import Axes
        from matplotlib.figure import Figure

        Artist.__init__(self)

        if prop is None:
            if fontsize is not None:
                self.prop = FontProperties(size=fontsize)
            else:
                self.prop = FontProperties(size=rcParams["legend.fontsize"])
        elif isinstance(prop, dict):
            self.prop = FontProperties(**prop)
            if "size" not in prop:
                self.prop.set_size(rcParams["legend.fontsize"])
        else:
            self.prop = prop

        self._fontsize = self.prop.get_size_in_points()

        self.texts = []
        self.legendHandles = []
        self._legend_title_box = None

        #: A dictionary with the extra handler mappings for this Legend
        #: instance.
        self._custom_handler_map = handler_map

        locals_view = locals()
        for name in [
                "numpoints", "markerscale", "shadow", "columnspacing",
                "scatterpoints", "handleheight", 'borderpad', 'labelspacing',
                'handlelength', 'handletextpad', 'borderaxespad'
        ]:
            if locals_view[name] is None:
                value = rcParams["legend." + name]
            else:
                value = locals_view[name]
            setattr(self, name, value)
        del locals_view
        # trim handles and labels if illegal label...
        _lab, _hand = [], []
        for label, handle in zip(labels, handles):
            if isinstance(label, str) and label.startswith('_'):
                warnings.warn('The handle {!r} has a label of {!r} which '
                              'cannot be automatically added to the '
                              'legend.'.format(handle, label))
            else:
                _lab.append(label)
                _hand.append(handle)
        labels, handles = _lab, _hand

        handles = list(handles)
        if len(handles) < 2:
            ncol = 1
        self._ncol = ncol

        if self.numpoints <= 0:
            raise ValueError("numpoints must be > 0; it was %d" % numpoints)

        # introduce y-offset for handles of the scatter plot
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3. / 8., 4. / 8., 2.5 / 8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps = self.scatterpoints // len(self._scatteryoffsets) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets,
                                        reps)[:self.scatterpoints]

        # _legend_box is an OffsetBox instance that contains all
        # legend items and will be initialized from _init_legend_box()
        # method.
        self._legend_box = None

        if isinstance(parent, Axes):
            self.isaxes = True
            self.axes = parent
            self.set_figure(parent.figure)
        elif isinstance(parent, Figure):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError("Legend needs either Axes or Figure as parent")
        self.parent = parent

        if loc is None:
            loc = rcParams["legend.loc"]
            if not self.isaxes and loc in [0, 'best']:
                loc = 'upper right'
        if isinstance(loc, str):
            if loc not in self.codes:
                if self.isaxes:
                    warnings.warn('Unrecognized location "%s". Falling back '
                                  'on "best"; valid locations are\n\t%s\n' %
                                  (loc, '\n\t'.join(self.codes)))
                    loc = 0
                else:
                    warnings.warn('Unrecognized location "%s". Falling back '
                                  'on "upper right"; '
                                  'valid locations are\n\t%s\n' %
                                  (loc, '\n\t'.join(self.codes)))
                    loc = 1
            else:
                loc = self.codes[loc]
        if not self.isaxes and loc == 0:
            warnings.warn('Automatic legend placement (loc="best") not '
                          'implemented for figure legend. '
                          'Falling back on "upper right".')
            loc = 1

        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

        # We use FancyBboxPatch to draw a legend frame. The location
        # and size of the box will be updated during the drawing time.

        if facecolor is None:
            facecolor = rcParams["legend.facecolor"]
        if facecolor == 'inherit':
            facecolor = rcParams["axes.facecolor"]

        if edgecolor is None:
            edgecolor = rcParams["legend.edgecolor"]
        if edgecolor == 'inherit':
            edgecolor = rcParams["axes.edgecolor"]

        self.legendPatch = FancyBboxPatch(xy=(0.0, 0.0),
                                          width=1.,
                                          height=1.,
                                          facecolor=facecolor,
                                          edgecolor=edgecolor,
                                          mutation_scale=self._fontsize,
                                          snap=True)

        # The width and height of the legendPatch will be set (in the
        # draw()) to the length that includes the padding. Thus we set
        # pad=0 here.
        if fancybox is None:
            fancybox = rcParams["legend.fancybox"]

        if fancybox:
            self.legendPatch.set_boxstyle("round", pad=0, rounding_size=0.2)
        else:
            self.legendPatch.set_boxstyle("square", pad=0)

        self._set_artist_props(self.legendPatch)

        self._drawFrame = frameon
        if frameon is None:
            self._drawFrame = rcParams["legend.frameon"]

        # init with null renderer
        self._init_legend_box(handles, labels, markerfirst)

        # If shadow is activated use framealpha if not
        # explicitly passed. See Issue 8943
        if framealpha is None:
            if shadow:
                self.get_frame().set_alpha(1)
            else:
                self.get_frame().set_alpha(rcParams["legend.framealpha"])
        else:
            self.get_frame().set_alpha(framealpha)

        self._loc = loc
        # figure out title fontsize:
        if title_fontsize is None:
            title_fontsize = rcParams['legend.title_fontsize']
        tprop = FontProperties(size=title_fontsize)
        self.set_title(title, prop=tprop)
        self._last_fontsize_points = self._fontsize
        self._draggable = None

    def _set_artist_props(self, a):
        """
        Set the boilerplate props for artists added to axes.
        """
        a.set_figure(self.figure)
        if self.isaxes:
            # a.set_axes(self.axes)
            a.axes = self.axes

        a.set_transform(self.get_transform())

    def _set_loc(self, loc):
        # find_offset function will be provided to _legend_box and
        # _legend_box will draw itself at the location of the return
        # value of the find_offset.
        self._loc_real = loc
        self.stale = True
        self._legend_box.set_offset(self._findoffset)

    def _get_loc(self):
        return self._loc_real

    _loc = property(_get_loc, _set_loc)

    def _findoffset(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend."

        if self._loc == 0:  # "best".
            x, y = self._find_best_position(width, height, renderer)
        elif self._loc in Legend.codes.values():  # Fixed location.
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox,
                                           self.get_bbox_to_anchor(), renderer)
        else:  # Axes or figure coordinates.
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy

        return x + xdescent, y + ydescent

    @allow_rasterization
    def draw(self, renderer):
        "Draw everything that belongs to the legend."
        if not self.get_visible():
            return

        renderer.open_group('legend')

        fontsize = renderer.points_to_pixels(self._fontsize)

        # if mode == fill, set the width of the legend_box to the
        # width of the paret (minus pads)
        if self._mode in ["expand"]:
            pad = 2 * (self.borderaxespad + self.borderpad) * fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width - pad)

        # update the location and size of the legend. This needs to
        # be done in any case to clip the figure right.
        bbox = self._legend_box.get_window_extent(renderer)
        self.legendPatch.set_bounds(bbox.x0, bbox.y0, bbox.width, bbox.height)
        self.legendPatch.set_mutation_scale(fontsize)

        if self._drawFrame:
            if self.shadow:
                shadow = Shadow(self.legendPatch, 2, -2)
                shadow.draw(renderer)

            self.legendPatch.draw(renderer)

        self._legend_box.draw(renderer)

        renderer.close_group('legend')
        self.stale = False

    def _approx_text_height(self, renderer=None):
        """
        Return the approximate height of the text. This is used to place
        the legend handle.
        """
        if renderer is None:
            return self._fontsize
        else:
            return renderer.points_to_pixels(self._fontsize)

    # _default_handler_map defines the default mapping between plot
    # elements and the legend handlers.

    _default_handler_map = {
        StemContainer:
        legend_handler.HandlerStem(),
        ErrorbarContainer:
        legend_handler.HandlerErrorbar(),
        Line2D:
        legend_handler.HandlerLine2D(),
        Patch:
        legend_handler.HandlerPatch(),
        LineCollection:
        legend_handler.HandlerLineCollection(),
        RegularPolyCollection:
        legend_handler.HandlerRegularPolyCollection(),
        CircleCollection:
        legend_handler.HandlerCircleCollection(),
        BarContainer:
        legend_handler.HandlerPatch(
            update_func=legend_handler.update_from_first_child),
        tuple:
        legend_handler.HandlerTuple(),
        PathCollection:
        legend_handler.HandlerPathCollection(),
        PolyCollection:
        legend_handler.HandlerPolyCollection()
    }

    # (get|set|update)_default_handler_maps are public interfaces to
    # modify the default handler map.

    @classmethod
    def get_default_handler_map(cls):
        """
        A class method that returns the default handler map.
        """
        return cls._default_handler_map

    @classmethod
    def set_default_handler_map(cls, handler_map):
        """
        A class method to set the default handler map.
        """
        cls._default_handler_map = handler_map

    @classmethod
    def update_default_handler_map(cls, handler_map):
        """
        A class method to update the default handler map.
        """
        cls._default_handler_map.update(handler_map)

    def get_legend_handler_map(self):
        """
        Return the handler map.
        """

        default_handler_map = self.get_default_handler_map()

        if self._custom_handler_map:
            hm = default_handler_map.copy()
            hm.update(self._custom_handler_map)
            return hm
        else:
            return default_handler_map

    @staticmethod
    def get_legend_handler(legend_handler_map, orig_handle):
        """
        Return a legend handler from *legend_handler_map* that
        corresponds to *orig_handler*.

        *legend_handler_map* should be a dictionary object (that is
        returned by the get_legend_handler_map method).

        It first checks if the *orig_handle* itself is a key in the
        *legend_hanler_map* and return the associated value.
        Otherwise, it checks for each of the classes in its
        method-resolution-order. If no matching key is found, it
        returns ``None``.
        """
        if is_hashable(orig_handle):
            try:
                return legend_handler_map[orig_handle]
            except KeyError:
                pass

        for handle_type in type(orig_handle).mro():
            try:
                return legend_handler_map[handle_type]
            except KeyError:
                pass

        return None

    def _init_legend_box(self, handles, labels, markerfirst=True):
        """
        Initialize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """

        fontsize = self._fontsize

        # legend_box is a HPacker, horizontally packed with
        # columns. Each column is a VPacker, vertically packed with
        # legend items. Each legend item is HPacker packed with
        # legend handleBox and labelBox. handleBox is an instance of
        # offsetbox.DrawingArea which contains legend handle. labelBox
        # is an instance of offsetbox.TextArea which contains legend
        # text.

        text_list = []  # the list of text instances
        handle_list = []  # the list of text instances
        handles_and_labels = []

        label_prop = dict(
            verticalalignment='baseline',
            horizontalalignment='left',
            fontproperties=self.prop,
        )

        # The approximate height and descent of text. These values are
        # only used for plotting the legend handle.
        descent = 0.35 * self._approx_text_height() * (self.handleheight - 0.7)
        # 0.35 and 0.7 are just heuristic numbers and may need to be improved.
        height = self._approx_text_height() * self.handleheight - descent
        # each handle needs to be drawn inside a box of (x, y, w, h) =
        # (0, -descent, width, height).  And their coordinates should
        # be given in the display coordinates.

        # The transformation of each handle will be automatically set
        # to self.get_trasnform(). If the artist does not use its
        # default transform (e.g., Collections), you need to
        # manually set their transform to the self.get_transform().
        legend_handler_map = self.get_legend_handler_map()

        for orig_handle, lab in zip(handles, labels):
            handler = self.get_legend_handler(legend_handler_map, orig_handle)
            if handler is None:
                warnings.warn(
                    "Legend does not support {!r} instances.\nA proxy artist "
                    "may be used instead.\nSee: "
                    "http://matplotlib.org/users/legend_guide.html"
                    "#creating-artists-specifically-for-adding-to-the-legend-"
                    "aka-proxy-artists".format(orig_handle))
                # We don't have a handle for this artist, so we just defer
                # to None.
                handle_list.append(None)
            else:
                textbox = TextArea(lab,
                                   textprops=label_prop,
                                   multilinebaseline=True,
                                   minimumdescent=True)
                handlebox = DrawingArea(width=self.handlelength * fontsize,
                                        height=height,
                                        xdescent=0.,
                                        ydescent=descent)

                text_list.append(textbox._text)
                # Create the artist for the legend which represents the
                # original artist/handle.
                handle_list.append(
                    handler.legend_artist(self, orig_handle, fontsize,
                                          handlebox))
                handles_and_labels.append((handlebox, textbox))

        if handles_and_labels:
            # We calculate number of rows in each column. The first
            # (num_largecol) columns will have (nrows+1) rows, and remaining
            # (num_smallcol) columns will have (nrows) rows.
            ncol = min(self._ncol, len(handles_and_labels))
            nrows, num_largecol = divmod(len(handles_and_labels), ncol)
            num_smallcol = ncol - num_largecol
            # starting index of each column and number of rows in it.
            rows_per_col = [nrows + 1] * num_largecol + [nrows] * num_smallcol
            start_idxs = np.concatenate([[0], np.cumsum(rows_per_col)[:-1]])
            cols = zip(start_idxs, rows_per_col)
        else:
            cols = []

        columnbox = []
        for i0, di in cols:
            # pack handleBox and labelBox into itemBox
            itemBoxes = [
                HPacker(pad=0,
                        sep=self.handletextpad * fontsize,
                        children=[h, t] if markerfirst else [t, h],
                        align="baseline")
                for h, t in handles_and_labels[i0:i0 + di]
            ]
            # minimumdescent=False for the text of the last row of the column
            if markerfirst:
                itemBoxes[-1].get_children()[1].set_minimumdescent(False)
            else:
                itemBoxes[-1].get_children()[0].set_minimumdescent(False)

            # pack columnBox
            alignment = "baseline" if markerfirst else "right"
            columnbox.append(
                VPacker(pad=0,
                        sep=self.labelspacing * fontsize,
                        align=alignment,
                        children=itemBoxes))

        mode = "expand" if self._mode == "expand" else "fixed"
        sep = self.columnspacing * fontsize
        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep,
                                          align="baseline",
                                          mode=mode,
                                          children=columnbox)
        self._legend_title_box = TextArea("")
        self._legend_box = VPacker(
            pad=self.borderpad * fontsize,
            sep=self.labelspacing * fontsize,
            align="center",
            children=[self._legend_title_box, self._legend_handle_box])
        self._legend_box.set_figure(self.figure)
        self.texts = text_list
        self.legendHandles = handle_list

    def _auto_legend_data(self):
        """
        Returns list of vertices and extents covered by the plot.

        Returns a two long list.

        First element is a list of (x, y) vertices (in
        display-coordinates) covered by all the lines and line
        collections, in the legend's handles.

        Second element is a list of bounding boxes for all the patches in
        the legend's handles.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        ax = self.parent
        bboxes = []
        lines = []
        offsets = []

        for handle in ax.lines:
            assert isinstance(handle, Line2D)
            path = handle.get_path()
            trans = handle.get_transform()
            tpath = trans.transform_path(path)
            lines.append(tpath)

        for handle in ax.patches:
            assert isinstance(handle, Patch)

            if isinstance(handle, Rectangle):
                transform = handle.get_data_transform()
                bboxes.append(handle.get_bbox().transformed(transform))
            else:
                transform = handle.get_transform()
                bboxes.append(handle.get_path().get_extents(transform))

        for handle in ax.collections:
            transform, transOffset, hoffsets, paths = handle._prepare_points()

            if len(hoffsets):
                for offset in transOffset.transform(hoffsets):
                    offsets.append(offset)

        try:
            vertices = np.concatenate([l.vertices for l in lines])
        except ValueError:
            vertices = np.array([])

        return [vertices, bboxes, lines, offsets]

    def draw_frame(self, b):
        '''
        Set draw frame to b.

        Parameters
        ----------
        b : bool
        '''
        self.set_frame_on(b)

    def get_children(self):
        'Return a list of child artists.'
        children = []
        if self._legend_box:
            children.append(self._legend_box)
        children.append(self.get_frame())

        return children

    def get_frame(self):
        '''
        Return the `~.patches.Rectangle` instances used to frame the legend.
        '''
        return self.legendPatch

    def get_lines(self):
        'Return a list of `~.lines.Line2D` instances in the legend.'
        return [h for h in self.legendHandles if isinstance(h, Line2D)]

    def get_patches(self):
        'Return a list of `~.patches.Patch` instances in the legend.'
        return silent_list(
            'Patch', [h for h in self.legendHandles if isinstance(h, Patch)])

    def get_texts(self):
        'Return a list of `~.text.Text` instances in the legend.'
        return silent_list('Text', self.texts)

    def set_title(self, title, prop=None):
        """
        Set the legend title. Fontproperties can be optionally set
        with *prop* parameter.
        """
        self._legend_title_box._text.set_text(title)
        if title:
            self._legend_title_box._text.set_visible(True)
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box._text.set_visible(False)
            self._legend_title_box.set_visible(False)

        if prop is not None:
            if isinstance(prop, dict):
                prop = FontProperties(**prop)
            self._legend_title_box._text.set_fontproperties(prop)

        self.stale = True

    def get_title(self):
        'Return the `.Text` instance for the legend title.'
        return self._legend_title_box._text

    def get_window_extent(self, *args, **kwargs):
        'Return extent of the legend.'
        return self._legend_box.get_window_extent(*args, **kwargs)

    def get_tightbbox(self, renderer):
        """
        Like `.Legend.get_window_extent`, but uses the box for the legend.

        Parameters
        ----------
        renderer : `.RendererBase` instance
            renderer that will be used to draw the figures (i.e.
            ``fig.canvas.get_renderer()``)

        Returns
        -------
        `.BboxBase` : containing the bounding box in figure pixel co-ordinates.
        """
        return self._legend_box.get_window_extent(renderer)

    def get_frame_on(self):
        """Get whether the legend box patch is drawn."""
        return self._drawFrame

    def set_frame_on(self, b):
        """
        Set whether the legend box patch is drawn.

        Parameters
        ----------
        b : bool
        """
        self._drawFrame = b
        self.stale = True

    def get_bbox_to_anchor(self):
        """Return the bbox that the legend will be anchored to."""
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor

    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        Set the bbox that the legend will be anchored to.

        *bbox* can be

        - A `.BboxBase` instance
        - A tuple of ``(left, bottom, width, height)`` in the given transform
          (normalized axes coordinate if None)
        - A tuple of ``(left, bottom)`` where the width and height will be
          assumed to be zero.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError:
                raise ValueError("Invalid argument for bbox : %s" % str(bbox))

            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]

            self._bbox_to_anchor = Bbox.from_bounds(*bbox)

        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)

        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor, transform)
        self.stale = True

    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x,y) coordinate of the bbox.

        - loc: a location code in range(1, 11).
          This corresponds to the possible values for self._loc, excluding
          "best".

        - bbox: bbox to be placed, display coordinate units.
        - parentbbox: a parent box which will contain the bbox. In
            display coordinates.
        """
        assert loc in range(1, 11)  # called only internally

        BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = range(11)

        anchor_coefs = {
            UR: "NE",
            UL: "NW",
            LL: "SW",
            LR: "SE",
            R: "E",
            CL: "W",
            CR: "E",
            LC: "S",
            UC: "N",
            C: "C"
        }

        c = anchor_coefs[loc]

        fontsize = renderer.points_to_pixels(self._fontsize)
        container = parentbbox.padded(-(self.borderaxespad) * fontsize)
        anchored_box = bbox.anchored(c, container=container)
        return anchored_box.x0, anchored_box.y0

    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.

        *consider* is a list of ``(x, y)`` pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        verts, bboxes, lines, offsets = self._auto_legend_data()

        bbox = Bbox.from_bounds(0, 0, width, height)
        if consider is None:
            consider = [
                self._get_anchored_bbox(x, bbox, self.get_bbox_to_anchor(),
                                        renderer)
                for x in range(1, len(self.codes))
            ]

        candidates = []
        for idx, (l, b) in enumerate(consider):
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            # XXX TODO: If markers are present, it would be good to
            # take them into account when checking vertex overlaps in
            # the next line.
            badness = (legendBox.count_contains(verts) +
                       legendBox.count_contains(offsets) +
                       legendBox.count_overlaps(bboxes) + sum(
                           line.intersects_bbox(legendBox, filled=False)
                           for line in lines))
            if badness == 0:
                return l, b
            # Include the index to favor lower codes in case of a tie.
            candidates.append((badness, idx, (l, b)))

        _, _, (l, b) = min(candidates)
        return l, b

    def contains(self, event):
        return self.legendPatch.contains(event)

    def set_draggable(self, state, use_blit=False, update='loc'):
        """
        Enable or disable mouse dragging support of the legend.

        Parameters
        ----------
        state : bool
            Whether mouse dragging is enabled.
        use_blit : bool, optional
            Use blitting for faster image composition. For details see
            :ref:`func-animation`.
        update : {'loc', 'bbox'}, optional
            The legend parameter to be changed when dragged:

            - 'loc': update the *loc* parameter of the legend
            - 'bbox': update the *bbox_to_anchor* parameter of the legend

        Returns
        -------
        If *state* is ``True`` this returns the `~.DraggableLegend` helper
        instance. Otherwise this returns ``None``.
        """
        if state:
            if self._draggable is None:
                self._draggable = DraggableLegend(self,
                                                  use_blit,
                                                  update=update)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None
        return self._draggable

    def get_draggable(self):
        """Return ``True`` if the legend is draggable, ``False`` otherwise."""
        return self._draggable is not None

    def draggable(self, state=None, use_blit=False, update="loc"):
        """
        Set the draggable state -- if state is

          * None : toggle the current state

          * True : turn draggable on

          * False : turn draggable off

        If draggable is on, you can drag the legend on the canvas with
        the mouse. The `.DraggableLegend` helper instance is returned if
        draggable is on.

        The update parameter control which parameter of the legend changes
        when dragged. If update is "loc", the *loc* parameter of the legend
        is changed. If "bbox", the *bbox_to_anchor* parameter is changed.
        """
        warn_deprecated("2.2",
                        message="Legend.draggable() is drepecated in "
                        "favor of Legend.set_draggable(). "
                        "Legend.draggable may be reintroduced as a "
                        "property in future releases.")

        if state is None:
            state = not self.get_draggable()  # toggle state

        self.set_draggable(state, use_blit, update)

        return self._draggable
Exemple #3
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.  Labels are a
    sequence of strings and loc can be a string or an integer
    specifying the legend location

    The location codes are::

      'best'         : 0, (only implemented for axis legends)
      'upper right'  : 1,
      'upper left'   : 2,
      'lower left'   : 3,
      'lower right'  : 4,
      'right'        : 5,
      'center left'  : 6,
      'center right' : 7,
      'lower center' : 8,
      'upper center' : 9,
      'center'       : 10,

    loc can be a tuple of the noramilzed coordinate values with
    respect its parent.

    """


    codes = {'best'         : 0, # only implemented for axis legends
             'upper right'  : 1,
             'upper left'   : 2,
             'lower left'   : 3,
             'lower right'  : 4,
             'right'        : 5,
             'center left'  : 6,
             'center right' : 7,
             'lower center' : 8,
             'upper center' : 9,
             'center'       : 10,
             }


    zorder = 5
    def __str__(self):
        return "Legend"

    def __init__(self, parent, handles, labels,
                 loc = None,
                 numpoints = None,     # the number of points in the legend line
                 markerscale = None,   # the relative size of legend markers vs. original
                 scatterpoints = 3,    # TODO: may be an rcParam
                 scatteryoffsets=None,
                 prop = None,          # properties for the legend texts

                 # the following dimensions are in axes coords
                 pad = None,           # deprecated; use borderpad
                 labelsep = None,      # deprecated; use labelspacing
                 handlelen = None,     # deprecated; use handlelength
                 handletextsep = None, # deprecated; use handletextpad
                 axespad = None,       # deprecated; use borderaxespad

                 # spacing & pad defined as a fraction of the font-size
                 borderpad = None,     # the whitespace inside the legend border
                 labelspacing=None, #the vertical space between the legend entries
                 handlelength=None, # the length of the legend handles
                 handleheight=None, # the height of the legend handles
                 handletextpad=None, # the pad between the legend handle and text
                 borderaxespad=None, # the pad between the axes and legend border
                 columnspacing=None, # spacing between columns

                 ncol=1, # number of columns
                 mode=None, # mode for horizontal distribution of columns. None, "expand"

                 fancybox=None, # True use a fancy box, false use a rounded box, none use rc
                 shadow = None,
                 title = None, # set a title for the legend
                 bbox_to_anchor = None, # bbox that the legend will be anchored.
                 bbox_transform = None, # transform for the bbox
                 frameon = None, # draw frame
                 handler_map = None,
                 ):
        """
        - *parent* : the artist that contains the legend
        - *handles* : a list of artists (lines, patches) to be added to the legend
        - *labels* : a list of strings to label the legend

        Optional keyword arguments:

        ================   ==================================================================
        Keyword            Description
        ================   ==================================================================
        loc                a location code
        prop               the font property
        markerscale        the relative size of legend markers vs. original
        numpoints          the number of points in the legend for line
        scatterpoints      the number of points in the legend for scatter plot
        scatteryoffsets    a list of yoffsets for scatter symbols in legend
        frameon            if True, draw a frame around the legend. If None, use rc
        fancybox           if True, draw a frame with a round fancybox.  If None, use rc
        shadow             if True, draw a shadow behind legend
        ncol               number of columns
        borderpad          the fractional whitespace inside the legend border
        labelspacing       the vertical space between the legend entries
        handlelength       the length of the legend handles
        handleheight       the length of the legend handles
        handletextpad      the pad between the legend handle and text
        borderaxespad      the pad between the axes and legend border
        columnspacing      the spacing between columns
        title              the legend title
        bbox_to_anchor     the bbox that the legend will be anchored.
        bbox_transform     the transform for the bbox. transAxes if None.
        ================   ==================================================================


The pad and spacing parameters are measured in font-size units.  E.g.,
a fontsize of 10 points and a handlelength=5 implies a handlelength of
50 points.  Values from rcParams will be used if None.

Users can specify any arbitrary location for the legend using the
*bbox_to_anchor* keyword argument. bbox_to_anchor can be an instance
of BboxBase(or its derivatives) or a tuple of 2 or 4 floats.
See :meth:`set_bbox_to_anchor` for more detail.

The legend location can be specified by setting *loc* with a tuple of
2 floats, which is interpreted as the lower-left corner of the legend
in the normalized axes coordinate.
        """
        from matplotlib.axes import Axes     # local import only to avoid circularity
        from matplotlib.figure import Figure # local import only to avoid circularity

        Artist.__init__(self)

        if prop is None:
            self.prop=FontProperties(size=rcParams["legend.fontsize"])
        elif isinstance(prop, dict):
            self.prop=FontProperties(**prop)
            if "size" not in prop:
                self.prop.set_size(rcParams["legend.fontsize"])
        else:
            self.prop=prop

        self._fontsize = self.prop.get_size_in_points()

        propnames=['numpoints', 'markerscale', 'shadow', "columnspacing",
                   "scatterpoints", "handleheight"]

        self.texts = []
        self.legendHandles = []
        self._legend_title_box = None


        self._handler_map = handler_map

        localdict = locals()

        for name in propnames:
            if localdict[name] is None:
                value = rcParams["legend."+name]
            else:
                value = localdict[name]
            setattr(self, name, value)

        # Take care the deprecated keywords
        deprecated_kwds = {"pad":"borderpad",
                           "labelsep":"labelspacing",
                           "handlelen":"handlelength",
                           "handletextsep":"handletextpad",
                           "axespad":"borderaxespad"}

        # convert values of deprecated keywords (ginve in axes coords)
        # to new vaules in a fraction of the font size

        # conversion factor
        bbox = parent.bbox
        axessize_fontsize = min(bbox.width, bbox.height)/self._fontsize

        for k, v in deprecated_kwds.iteritems():
            # use deprecated value if not None and if their newer
            # counter part is None.
            if localdict[k] is not None and localdict[v] is None:
                warnings.warn("Use '%s' instead of '%s'." % (v, k),
                              DeprecationWarning)
                setattr(self, v, localdict[k]*axessize_fontsize)
                continue

            # Otherwise, use new keywords
            if localdict[v] is None:
                setattr(self, v, rcParams["legend."+v])
            else:
                setattr(self, v, localdict[v])

        del localdict

        handles = list(handles)
        if len(handles)<2:
            ncol = 1
        self._ncol = ncol

        if self.numpoints <= 0:
            raise ValueError("numpoints must be > 0; it was %d"% numpoints)

        # introduce y-offset for handles of the scatter plot
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3./8., 4./8., 2.5/8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps =  int(self.scatterpoints / len(self._scatteryoffsets)) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets, reps)[:self.scatterpoints]

        # _legend_box is an OffsetBox instance that contains all
        # legend items and will be initialized from _init_legend_box()
        # method.
        self._legend_box = None

        if isinstance(parent,Axes):
            self.isaxes = True
            self.set_axes(parent)
            self.set_figure(parent.figure)
        elif isinstance(parent,Figure):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError("Legend needs either Axes or Figure as parent")
        self.parent = parent

        if loc is None:
            loc = rcParams["legend.loc"]
            if not self.isaxes and loc in [0,'best']:
                loc = 'upper right'
        if is_string_like(loc):
            if loc not in self.codes:
                if self.isaxes:
                    warnings.warn('Unrecognized location "%s". Falling back on "best"; '
                                  'valid locations are\n\t%s\n'
                                  % (loc, '\n\t'.join(self.codes.iterkeys())))
                    loc = 0
                else:
                    warnings.warn('Unrecognized location "%s". Falling back on "upper right"; '
                                  'valid locations are\n\t%s\n'
                                   % (loc, '\n\t'.join(self.codes.iterkeys())))
                    loc = 1
            else:
                loc = self.codes[loc]
        if not self.isaxes and loc == 0:
            warnings.warn('Automatic legend placement (loc="best") not implemented for figure legend. '
                          'Falling back on "upper right".')
            loc = 1

        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

        # We use FancyBboxPatch to draw a legend frame. The location
        # and size of the box will be updated during the drawing time.

        self.legendPatch = FancyBboxPatch(
            xy=(0.0, 0.0), width=1., height=1.,
            facecolor=rcParams["axes.facecolor"],
            edgecolor=rcParams["axes.edgecolor"],
            mutation_scale=self._fontsize,
            snap=True
            )

        # The width and height of the legendPatch will be set (in the
        # draw()) to the length that includes the padding. Thus we set
        # pad=0 here.
        if fancybox is None:
            fancybox = rcParams["legend.fancybox"]

        if fancybox == True:
            self.legendPatch.set_boxstyle("round",pad=0,
                                          rounding_size=0.2)
        else:
            self.legendPatch.set_boxstyle("square",pad=0)

        self._set_artist_props(self.legendPatch)

        self._drawFrame = frameon
        if frameon is None:
            self._drawFrame = rcParams["legend.frameon"]

        # init with null renderer
        self._init_legend_box(handles, labels)

        self._loc = loc

        self.set_title(title)

        self._last_fontsize_points = self._fontsize

        self._draggable = None

    def _set_artist_props(self, a):
        """
        set the boilerplate props for artists added to axes
        """
        a.set_figure(self.figure)
        if self.isaxes:
            a.set_axes(self.axes)
        a.set_transform(self.get_transform())


    def _set_loc(self, loc):
        # find_offset function will be provided to _legend_box and
        # _legend_box will draw itself at the location of the return
        # value of the find_offset.
        self._loc_real = loc
        if loc == 0:
            _findoffset = self._findoffset_best
        else:
            _findoffset = self._findoffset_loc

        #def findoffset(width, height, xdescent, ydescent):
        #    return _findoffset(width, height, xdescent, ydescent, renderer)

        self._legend_box.set_offset(_findoffset)

        self._loc_real = loc

    def _get_loc(self):
        return self._loc_real

    _loc = property(_get_loc, _set_loc)

    def _findoffset_best(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend at its best position"
        ox, oy = self._find_best_position(width, height, renderer)
        return ox+xdescent, oy+ydescent

    def _findoffset_loc(self, width, height, xdescent, ydescent, renderer):
        "Heper function to locate the legend using the location code"

        if iterable(self._loc) and len(self._loc)==2:
            # when loc is a tuple of axes(or figure) coordinates.
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy
        else:
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox, self.get_bbox_to_anchor(), renderer)

        return x+xdescent, y+ydescent

    @allow_rasterization
    def draw(self, renderer):
        "Draw everything that belongs to the legend"
        if not self.get_visible(): return


        renderer.open_group('legend')


        fontsize = renderer.points_to_pixels(self._fontsize)

        # if mode == fill, set the width of the legend_box to the
        # width of the paret (minus pads)
        if self._mode in ["expand"]:
            pad = 2*(self.borderaxespad+self.borderpad)*fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width-pad)

        if self._drawFrame:
            # update the location and size of the legend
            bbox = self._legend_box.get_window_extent(renderer)
            self.legendPatch.set_bounds(bbox.x0, bbox.y0,
                                        bbox.width, bbox.height)

            self.legendPatch.set_mutation_scale(fontsize)

            if self.shadow:
                shadow = Shadow(self.legendPatch, 2, -2)
                shadow.draw(renderer)

            self.legendPatch.draw(renderer)

        self._legend_box.draw(renderer)

        renderer.close_group('legend')


    def _approx_text_height(self, renderer=None):
        """
        Return the approximate height of the text. This is used to place
        the legend handle.
        """
        if renderer is None:
            return self._fontsize
        else:
            return renderer.points_to_pixels(self._fontsize)


    # _default_handler_map defines the default mapping between plot
    # elements and the legend handlers.

    _default_handler_map = {
        StemContainer:legend_handler.HandlerStem(),
        ErrorbarContainer:legend_handler.HandlerErrorbar(),
        Line2D:legend_handler.HandlerLine2D(),
        Patch:legend_handler.HandlerPatch(),
        LineCollection:legend_handler.HandlerLineCollection(),
        RegularPolyCollection:legend_handler.HandlerRegularPolyCollection(),
        CircleCollection:legend_handler.HandlerCircleCollection(),
        BarContainer:legend_handler.HandlerPatch(update_func=legend_handler.update_from_first_child),
        tuple:legend_handler.HandlerTuple(),
        PathCollection:legend_handler.HandlerPathCollection()
        }

    # (get|set|update)_default_handler_maps are public interfaces to
    # modify the defalut handler map.

    @classmethod
    def get_default_handler_map(cls):
        """
        A class method that returns the default handler map.
        """
        return cls._default_handler_map

    @classmethod
    def set_default_handler_map(cls, handler_map):
        """
        A class method to set the default handler map.
        """
        cls._default_handler_map = handler_map

    @classmethod
    def update_default_handler_map(cls, handler_map):
        """
        A class method to update the default handler map.
        """
        cls._default_handler_map.update(handler_map)

    def get_legend_handler_map(self):
        """
        return the handler map.
        """

        default_handler_map = self.get_default_handler_map()

        if self._handler_map:
            hm = default_handler_map.copy()
            hm.update(self._handler_map)
            return hm
        else:
            return default_handler_map

    @staticmethod
    def get_legend_handler(legend_handler_map, orig_handle):
        """
        return a legend handler from *legend_handler_map* that
        corresponds to *orig_handler*.

        *legend_handler_map* should be a dictionary object (that is
        returned by the get_legend_handler_map method).

        It first checks if the *orig_handle* itself is a key in the
        *legend_hanler_map* and return the associated value.
        Otherwised, it checks for each of the classes in its
        method-resolution-order. If no matching key is found, it
        returns None.
        """
        legend_handler_keys = legend_handler_map.keys()
        if orig_handle in legend_handler_keys:
            handler = legend_handler_map[orig_handle]
        else:

            for handle_type in type(orig_handle).mro():
                if handle_type in legend_handler_map:
                    handler = legend_handler_map[handle_type]
                    break
            else:
                handler = None

        return handler


    def _init_legend_box(self, handles, labels):
        """
        Initiallize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """

        fontsize = self._fontsize

        # legend_box is a HPacker, horizontally packed with
        # columns. Each column is a VPacker, vertically packed with
        # legend items. Each legend item is HPacker packed with
        # legend handleBox and labelBox. handleBox is an instance of
        # offsetbox.DrawingArea which contains legend handle. labelBox
        # is an instance of offsetbox.TextArea which contains legend
        # text.


        text_list = []  # the list of text instances
        handle_list = []  # the list of text instances

        label_prop = dict(verticalalignment='baseline',
                          horizontalalignment='left',
                          fontproperties=self.prop,
                          )

        labelboxes = []
        handleboxes = []


        # The approximate height and descent of text. These values are
        # only used for plotting the legend handle.
        descent = 0.35*self._approx_text_height()*(self.handleheight - 0.7)
        # 0.35 and 0.7 are just heuristic numbers. this may need to be improbed
        height = self._approx_text_height() * self.handleheight - descent
        # each handle needs to be drawn inside a box of (x, y, w, h) =
        # (0, -descent, width, height).  And their corrdinates should
        # be given in the display coordinates.

        # The transformation of each handle will be automatically set
        # to self.get_trasnform(). If the artist does not uses its
        # default trasnform (eg, Collections), you need to
        # manually set their transform to the self.get_transform().


        legend_handler_map = self.get_legend_handler_map()

        for orig_handle, lab in zip(handles, labels):

            handler = self.get_legend_handler(legend_handler_map, orig_handle)

            if handler is None:
                warnings.warn("Legend does not support %s\nUse proxy artist instead.\n\nhttp://matplotlib.sourceforge.net/users/legend_guide.html#using-proxy-artist\n" % (str(orig_handle),))
                handle_list.append(None)
                continue

            textbox = TextArea(lab, textprops=label_prop,
                               multilinebaseline=True, minimumdescent=True)
            text_list.append(textbox._text)

            labelboxes.append(textbox)

            handlebox = DrawingArea(width=self.handlelength*fontsize,
                                    height=height,
                                    xdescent=0., ydescent=descent)

            handle = handler(self, orig_handle, \
                             #xdescent, ydescent, width, height,
                             fontsize,
                             handlebox)
            handle_list.append(handle)




            handleboxes.append(handlebox)


        if len(handleboxes) > 0:

            # We calculate number of lows in each column. The first
            # (num_largecol) columns will have (nrows+1) rows, and remaing
            # (num_smallcol) columns will have (nrows) rows.
            ncol = min(self._ncol, len(handleboxes))
            nrows, num_largecol = divmod(len(handleboxes), ncol)
            num_smallcol = ncol-num_largecol

            # starting index of each column and number of rows in it.
            largecol = safezip(range(0, num_largecol*(nrows+1), (nrows+1)),
                               [nrows+1] * num_largecol)
            smallcol = safezip(range(num_largecol*(nrows+1), len(handleboxes), nrows),
                               [nrows] * num_smallcol)
        else:
            largecol, smallcol = [], []

        handle_label = safezip(handleboxes, labelboxes)
        columnbox = []
        for i0, di in largecol+smallcol:
            # pack handleBox and labelBox into itemBox
            itemBoxes = [HPacker(pad=0,
                                 sep=self.handletextpad*fontsize,
                                 children=[h, t], align="baseline")
                         for h, t in handle_label[i0:i0+di]]
            # minimumdescent=False for the text of the last row of the column
            itemBoxes[-1].get_children()[1].set_minimumdescent(False)

            # pack columnBox
            columnbox.append(VPacker(pad=0,
                                        sep=self.labelspacing*fontsize,
                                        align="baseline",
                                        children=itemBoxes))

        if self._mode == "expand":
            mode = "expand"
        else:
            mode = "fixed"

        sep = self.columnspacing*fontsize

        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep, align="baseline",
                                          mode=mode,
                                          children=columnbox)

        self._legend_title_box = TextArea("")

        self._legend_box = VPacker(pad=self.borderpad*fontsize,
                                   sep=self.labelspacing*fontsize,
                                   align="center",
                                   children=[self._legend_title_box,
                                             self._legend_handle_box])

        self._legend_box.set_figure(self.figure)

        self.texts = text_list
        self.legendHandles = handle_list


    def _auto_legend_data(self):
        """
        Returns list of vertices and extents covered by the plot.

        Returns a two long list.

        First element is a list of (x, y) vertices (in
        display-coordinates) covered by all the lines and line
        collections, in the legend's handles.

        Second element is a list of bounding boxes for all the patches in
        the legend's handles.
        """

        assert self.isaxes # should always hold because function is only called internally

        ax = self.parent
        vertices = []
        bboxes = []
        lines = []

        for handle in ax.lines:
            assert isinstance(handle, Line2D)
            path = handle.get_path()
            trans = handle.get_transform()
            tpath = trans.transform_path(path)
            lines.append(tpath)

        for handle in ax.patches:
            assert isinstance(handle, Patch)

            if isinstance(handle, Rectangle):
                transform = handle.get_data_transform()
                bboxes.append(handle.get_bbox().transformed(transform))
            else:
                transform = handle.get_transform()
                bboxes.append(handle.get_path().get_extents(transform))

        return [vertices, bboxes, lines]

    def draw_frame(self, b):
        'b is a boolean.  Set draw frame to b'
        self.set_frame_on(b)

    def get_children(self):
        'return a list of child artists'
        children = []
        if self._legend_box:
            children.append(self._legend_box)
        children.extend(self.get_lines())
        children.extend(self.get_patches())
        children.extend(self.get_texts())
        children.append(self.get_frame())

        if self._legend_title_box:
            children.append(self.get_title())
        return children

    def get_frame(self):
        'return the Rectangle instance used to frame the legend'
        return self.legendPatch

    def get_lines(self):
        'return a list of lines.Line2D instances in the legend'
        return [h for h in self.legendHandles if isinstance(h, Line2D)]

    def get_patches(self):
        'return a list of patch instances in the legend'
        return silent_list('Patch', [h for h in self.legendHandles if isinstance(h, Patch)])

    def get_texts(self):
        'return a list of text.Text instance in the legend'
        return silent_list('Text', self.texts)

    def set_title(self, title, prop=None):
        """
        set the legend title. Fontproperties can be optionally set
        with *prop* parameter.
        """
        self._legend_title_box._text.set_text(title)

        if prop is not None:
            if isinstance(prop, dict):
                prop = FontProperties(**prop)
            self._legend_title_box._text.set_fontproperties(prop)

        if title:
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box.set_visible(False)

    def get_title(self):
        'return Text instance for the legend title'
        return self._legend_title_box._text

    def get_window_extent(self, *args, **kwargs) :
        'return a extent of the the legend'
        return self.legendPatch.get_window_extent(*args, **kwargs)


    def get_frame_on(self):
        """
        Get whether the legend box patch is drawn
        """
        return self._drawFrame

    def set_frame_on(self, b):
        """
        Set whether the legend box patch is drawn

        ACCEPTS: [ *True* | *False* ]
        """
        self._drawFrame = b

    def get_bbox_to_anchor(self):
        """
        return the bbox that the legend will be anchored
        """
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor


    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        set the bbox that the legend will be anchored.

        *bbox* can be a BboxBase instance, a tuple of [left, bottom,
        width, height] in the given transform (normalized axes
        coordinate if None), or a tuple of [left, bottom] where the
        width and height will be assumed to be zero.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError:
                raise ValueError("Invalid argument for bbox : %s" % str(bbox))

            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]

            self._bbox_to_anchor = Bbox.from_bounds(*bbox)

        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)

        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor,
                                               transform)



    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x,y) coordinate of the bbox.

        - loc: a location code in range(1, 11).
          This corresponds to the possible values for self._loc, excluding "best".

        - bbox: bbox to be placed, display coodinate units.
        - parentbbox: a parent box which will contain the bbox. In
            display coordinates.
        """
        assert loc in range(1,11) # called only internally

        BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = range(11)

        anchor_coefs={UR:"NE",
                      UL:"NW",
                      LL:"SW",
                      LR:"SE",
                      R:"E",
                      CL:"W",
                      CR:"E",
                      LC:"S",
                      UC:"N",
                      C:"C"}

        c = anchor_coefs[loc]

        fontsize = renderer.points_to_pixels(self._fontsize)
        container = parentbbox.padded(-(self.borderaxespad) * fontsize)
        anchored_box = bbox.anchored(c, container=container)
        return anchored_box.x0, anchored_box.y0


    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.

        `consider` is a list of (x, y) pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """

        assert self.isaxes # should always hold because function is only called internally

        verts, bboxes, lines = self._auto_legend_data()

        bbox = Bbox.from_bounds(0, 0, width, height)
        consider = [self._get_anchored_bbox(x, bbox, self.get_bbox_to_anchor(),
                                            renderer) for x in range(1, len(self.codes))]

        #tx, ty = self.legendPatch.get_x(), self.legendPatch.get_y()

        candidates = []
        for l, b in consider:
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            badness = legendBox.count_contains(verts)
            badness += legendBox.count_overlaps(bboxes)
            for line in lines:
                if line.intersects_bbox(legendBox):
                    badness += 1

            ox, oy = l, b
            if badness == 0:
                return ox, oy

            candidates.append((badness, (l, b)))

        # rather than use min() or list.sort(), do this so that we are assured
        # that in the case of two equal badnesses, the one first considered is
        # returned.
        # NOTE: list.sort() is stable.But leave as it is for now. -JJL
        minCandidate = candidates[0]
        for candidate in candidates:
            if candidate[0] < minCandidate[0]:
                minCandidate = candidate

        ox, oy = minCandidate[1]

        return ox, oy

    def contains(self, event):
        return self.legendPatch.contains(event)

    def draggable(self, state=None, use_blit=False, update="loc"):
        """
        Set the draggable state -- if state is

          * None : toggle the current state

          * True : turn draggable on

          * False : turn draggable off

        If draggable is on, you can drag the legend on the canvas with
        the mouse.  The DraggableLegend helper instance is returned if
        draggable is on.

        The update parameter control which parameter of the legend changes
        when dragged. If update is "loc", the *loc* paramter of the legend
        is changed. If "bbox", the *bbox_to_anchor* parameter is changed.
        """
        is_draggable = self._draggable is not None

        # if state is None we'll toggle
        if state is None:
            state = not is_draggable

        if state:
            if self._draggable is None:
                self._draggable = DraggableLegend(self, use_blit, update=update)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None

        return self._draggable
Exemple #4
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.  Labels are a
    sequence of strings and loc can be a string or an integer
    specifying the legend location
    The location codes are::
      'best'         : 0, (only implemented for axis legends)
      'upper right'  : 1,
      'upper left'   : 2,
      'lower left'   : 3,
      'lower right'  : 4,
      'right'        : 5,
      'center left'  : 6,
      'center right' : 7,
      'lower center' : 8,
      'upper center' : 9,
      'center'       : 10,
    loc can be a tuple of the noramilzed coordinate values with
    respect its parent.
    Return value is a sequence of text, line instances that make
    up the legend
    """
    codes = {'best'         : 0, # only implemented for axis legends
             'upper right'  : 1,
             'upper left'   : 2,
             'lower left'   : 3,
             'lower right'  : 4,
             'right'        : 5,
             'center left'  : 6,
             'center right' : 7,
             'lower center' : 8,
             'upper center' : 9,
             'center'       : 10,
             }
    zorder = 5
    def __str__(self):
        return "Legend"
    def __init__(self, parent, handles, labels,
                 loc = None,
                 numpoints = None,     # the number of points in the legend line
                 markerscale = None,   # the relative size of legend markers vs. original
                 scatterpoints = 3,    # TODO: may be an rcParam
                 scatteryoffsets=None,
                 prop = None,          # properties for the legend texts
                 pad = None,           # deprecated; use borderpad
                 labelsep = None,      # deprecated; use labelspacing
                 handlelen = None,     # deprecated; use handlelength
                 handletextsep = None, # deprecated; use handletextpad
                 axespad = None,       # deprecated; use borderaxespad
                 borderpad = None,     # the whitespace inside the legend border
                 labelspacing=None, #the vertical space between the legend entries
                 handlelength=None, # the length of the legend handles
                 handletextpad=None, # the pad between the legend handle and text
                 borderaxespad=None, # the pad between the axes and legend border
                 columnspacing=None, # spacing between columns
                 ncol=1, # number of columns
                 mode=None, # mode for horizontal distribution of columns. None, "expand"
                 fancybox=None, # True use a fancy box, false use a rounded box, none use rc
                 shadow = None,
                 title = None, # set a title for the legend
                 bbox_to_anchor = None, # bbox that the legend will be anchored.
                 bbox_transform = None, # transform for the bbox
                 frameon = True, # draw frame
                 ):
        """
        - *parent* : the artist that contains the legend
        - *handles* : a list of artists (lines, patches) to add to the legend
        - *labels* : a list of strings to label the legend
        Optional keyword arguments:
        ================   ==================================================================
        Keyword            Description
        ================   ==================================================================
        loc                a location code
        prop               the font property
        markerscale        the relative size of legend markers vs. original
        numpoints          the number of points in the legend for line
        scatterpoints      the number of points in the legend for scatter plot
        scatteryoffsets    a list of yoffsets for scatter symbols in legend
        frameon            if True, draw a frame (default is True)
        fancybox           if True, draw a frame with a round fancybox.  If None, use rc
        shadow             if True, draw a shadow behind legend
        ncol               number of columns
        borderpad          the fractional whitespace inside the legend border
        labelspacing       the vertical space between the legend entries
        handlelength       the length of the legend handles
        handletextpad      the pad between the legend handle and text
        borderaxespad      the pad between the axes and legend border
        columnspacing      the spacing between columns
        title              the legend title
        bbox_to_anchor     the bbox that the legend will be anchored.
        bbox_transform     the transform for the bbox. transAxes if None.
        ================   ==================================================================
The pad and spacing parameters are measure in font-size units.  E.g.,
a fontsize of 10 points and a handlelength=5 implies a handlelength of
50 points.  Values from rcParams will be used if None.
Users can specify any arbitrary location for the legend using the
*bbox_to_anchor* keyword argument. bbox_to_anchor can be an instance
of BboxBase(or its derivatives) or a tuple of 2 or 4 floats.
See :meth:`set_bbox_to_anchor` for more detail.
The legend location can be specified by setting *loc* with a tuple of
2 floats, which is interpreted as the lower-left corner of the legend
in the normalized axes coordinate.
        """
        from matplotlib.axes import Axes     # local import only to avoid circularity
        from matplotlib.figure import Figure # local import only to avoid circularity
        Artist.__init__(self)
        if prop is None:
            self.prop=FontProperties(size=rcParams["legend.fontsize"])
        elif isinstance(prop, dict):
            self.prop=FontProperties(**prop)
            if "size" not in prop:
                self.prop.set_size(rcParams["legend.fontsize"])
        else:
            self.prop=prop
        self._fontsize = self.prop.get_size_in_points()
        propnames=['numpoints', 'markerscale', 'shadow', "columnspacing",
                   "scatterpoints"]
        self.texts = []
        self.legendHandles = []
        self._legend_title_box = None
        localdict = locals()
        for name in propnames:
            if localdict[name] is None:
                value = rcParams["legend."+name]
            else:
                value = localdict[name]
            setattr(self, name, value)
        deprecated_kwds = {"pad":"borderpad",
                           "labelsep":"labelspacing",
                           "handlelen":"handlelength",
                           "handletextsep":"handletextpad",
                           "axespad":"borderaxespad"}
        bbox = parent.bbox
        axessize_fontsize = min(bbox.width, bbox.height)/self._fontsize
        for k, v in deprecated_kwds.items():
            if localdict[k] is not None and localdict[v] is None:
                warnings.warn("Use '%s' instead of '%s'." % (v, k),
                              DeprecationWarning)
                setattr(self, v, localdict[k]*axessize_fontsize)
                continue
            if localdict[v] is None:
                setattr(self, v, rcParams["legend."+v])
            else:
                setattr(self, v, localdict[v])
        del localdict
        handles = list(handles)
        if len(handles)<2:
            ncol = 1
        self._ncol = ncol
        if self.numpoints <= 0:
            raise ValueError("numpoints must be >= 0; it was %d"% numpoints)
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3./8., 4./8., 2.5/8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps =  int(self.numpoints / len(self._scatteryoffsets)) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets, reps)[:self.scatterpoints]
        self._legend_box = None
        if isinstance(parent,Axes):
            self.isaxes = True
            self.set_axes(parent)
            self.set_figure(parent.figure)
        elif isinstance(parent,Figure):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError("Legend needs either Axes or Figure as parent")
        self.parent = parent
        if loc is None:
            loc = rcParams["legend.loc"]
            if not self.isaxes and loc in [0,'best']:
                loc = 'upper right'
        if is_string_like(loc):
            if loc not in self.codes:
                if self.isaxes:
                    warnings.warn('Unrecognized location "%s". Falling back on "best"; '
                                  'valid locations are\n\t%s\n'
                                  % (loc, '\n\t'.join(self.codes.keys())))
                    loc = 0
                else:
                    warnings.warn('Unrecognized location "%s". Falling back on "upper right"; '
                                  'valid locations are\n\t%s\n'
                                   % (loc, '\n\t'.join(self.codes.keys())))
                    loc = 1
            else:
                loc = self.codes[loc]
        if not self.isaxes and loc == 0:
            warnings.warn('Automatic legend placement (loc="best") not implemented for figure legend. '
                          'Falling back on "upper right".')
            loc = 1
        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)
        self.legendPatch = FancyBboxPatch(
            xy=(0.0, 0.0), width=1., height=1.,
            facecolor=rcParams["axes.facecolor"],
            edgecolor=rcParams["axes.edgecolor"],
            mutation_scale=self._fontsize,
            snap=True
            )
        if fancybox is None:
            fancybox = rcParams["legend.fancybox"]
        if fancybox == True:
            self.legendPatch.set_boxstyle("round",pad=0,
                                          rounding_size=0.2)
        else:
            self.legendPatch.set_boxstyle("square",pad=0)
        self._set_artist_props(self.legendPatch)
        self._drawFrame = frameon
        self._init_legend_box(handles, labels)
        self._loc = loc
        self.set_title(title)
        self._last_fontsize_points = self._fontsize
        self._draggable = None
    def _set_artist_props(self, a):
        """
        set the boilerplate props for artists added to axes
        """
        a.set_figure(self.figure)
        if self.isaxes:
            a.set_axes(self.axes)
        a.set_transform(self.get_transform())
    def _set_loc(self, loc):
        self._loc_real = loc
        if loc == 0:
            _findoffset = self._findoffset_best
        else:
            _findoffset = self._findoffset_loc
        self._legend_box.set_offset(_findoffset)
        self._loc_real = loc
    def _get_loc(self):
        return self._loc_real
    _loc = property(_get_loc, _set_loc)
    def _findoffset_best(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend at its best position"
        ox, oy = self._find_best_position(width, height, renderer)
        return ox+xdescent, oy+ydescent
    def _findoffset_loc(self, width, height, xdescent, ydescent, renderer):
        "Heper function to locate the legend using the location code"
        if iterable(self._loc) and len(self._loc)==2:
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy
        else:
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox, self.get_bbox_to_anchor(), renderer)
        return x+xdescent, y+ydescent
    @allow_rasterization
    def draw(self, renderer):
        "Draw everything that belongs to the legend"
        if not self.get_visible(): return
        renderer.open_group('legend')
        fontsize = renderer.points_to_pixels(self._fontsize)
        if self._mode in ["expand"]:
            pad = 2*(self.borderaxespad+self.borderpad)*fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width-pad)
        if self._drawFrame:
            bbox = self._legend_box.get_window_extent(renderer)
            self.legendPatch.set_bounds(bbox.x0, bbox.y0,
                                        bbox.width, bbox.height)
            self.legendPatch.set_mutation_scale(fontsize)
            if self.shadow:
                shadow = Shadow(self.legendPatch, 2, -2)
                shadow.draw(renderer)
            self.legendPatch.draw(renderer)
        self._legend_box.draw(renderer)
        renderer.close_group('legend')
    def _approx_text_height(self, renderer=None):
        """
        Return the approximate height of the text. This is used to place
        the legend handle.
        """
        if renderer is None:
            return self._fontsize
        else:
            return renderer.points_to_pixels(self._fontsize)
    def _init_legend_box(self, handles, labels):
        """
        Initiallize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """
        fontsize = self._fontsize
        text_list = []  # the list of text instances
        handle_list = []  # the list of text instances
        label_prop = dict(verticalalignment='baseline',
                          horizontalalignment='left',
                          fontproperties=self.prop,
                          )
        labelboxes = []
        handleboxes = []
        height = self._approx_text_height() * 0.7
        descent = 0.
        for handle, lab in zip(handles, labels):
            if isinstance(handle, RegularPolyCollection) or \
                   isinstance(handle, CircleCollection):
                npoints = self.scatterpoints
            else:
                npoints = self.numpoints
            if npoints > 1:
                xdata = np.linspace(0.3*fontsize,
                                    (self.handlelength-0.3)*fontsize,
                                    npoints)
                xdata_marker = xdata
            elif npoints == 1:
                xdata = np.linspace(0, self.handlelength*fontsize, 2)
                xdata_marker = [0.5*self.handlelength*fontsize]
            if isinstance(handle, Line2D):
                ydata = ((height-descent)/2.)*np.ones(xdata.shape, float)
                legline = Line2D(xdata, ydata)
                legline.update_from(handle)
                self._set_artist_props(legline) # after update
                legline.set_clip_box(None)
                legline.set_clip_path(None)
                legline.set_drawstyle('default')
                legline.set_marker('None')
                handle_list.append(legline)
                legline_marker = Line2D(xdata_marker, ydata[:len(xdata_marker)])
                legline_marker.update_from(handle)
                self._set_artist_props(legline_marker)
                legline_marker.set_clip_box(None)
                legline_marker.set_clip_path(None)
                legline_marker.set_linestyle('None')
                legline._legmarker = legline_marker
            elif isinstance(handle, Patch):
                p = Rectangle(xy=(0., 0.),
                              width = self.handlelength*fontsize,
                              height=(height-descent),
                              )
                p.update_from(handle)
                self._set_artist_props(p)
                p.set_clip_box(None)
                p.set_clip_path(None)
                handle_list.append(p)
            elif isinstance(handle, LineCollection):
                ydata = ((height-descent)/2.)*np.ones(xdata.shape, float)
                legline = Line2D(xdata, ydata)
                self._set_artist_props(legline)
                legline.set_clip_box(None)
                legline.set_clip_path(None)
                lw = handle.get_linewidth()[0]
                dashes = handle.get_dashes()[0]
                color = handle.get_colors()[0]
                legline.set_color(color)
                legline.set_linewidth(lw)
                if dashes[0] is not None: # dashed line
                    legline.set_dashes(dashes[1])
                handle_list.append(legline)
            elif isinstance(handle, RegularPolyCollection):
                ydata = height*self._scatteryoffsets
                size_max, size_min = max(handle.get_sizes()),\
                                     min(handle.get_sizes())
                if self.scatterpoints < 4:
                    sizes = [.5*(size_max+size_min), size_max,
                             size_min]
                else:
                    sizes = (size_max-size_min)*np.linspace(0,1,self.scatterpoints)+size_min
                p = type(handle)(handle.get_numsides(),
                                 rotation=handle.get_rotation(),
                                 sizes=sizes,
                                 offsets=zip(xdata_marker,ydata),
                                 transOffset=self.get_transform(),
                                 )
                p.update_from(handle)
                p.set_figure(self.figure)
                p.set_clip_box(None)
                p.set_clip_path(None)
                handle_list.append(p)
            elif isinstance(handle, CircleCollection):
                ydata = height*self._scatteryoffsets
                size_max, size_min = max(handle.get_sizes()),\
                                     min(handle.get_sizes())
                if self.scatterpoints < 4:
                    sizes = [.5*(size_max+size_min), size_max,
                             size_min]
                else:
                    sizes = (size_max-size_min)*np.linspace(0,1,self.scatterpoints)+size_min
                p = type(handle)(sizes,
                                 offsets=zip(xdata_marker,ydata),
                                 transOffset=self.get_transform(),
                                 )
                p.update_from(handle)
                p.set_figure(self.figure)
                p.set_clip_box(None)
                p.set_clip_path(None)
                handle_list.append(p)
            else:
                handle_type = type(handle)
                warnings.warn("Legend does not support %s\nUse proxy artist instead.\n\nhttp://matplotlib.sourceforge.net/users/legend_guide.html#using-proxy-artist\n" % (str(handle_type),))
                handle_list.append(None)
            handle = handle_list[-1]
            if handle is not None: # handle is None is the artist is not supproted
                textbox = TextArea(lab, textprops=label_prop,
                                   multilinebaseline=True, minimumdescent=True)
                text_list.append(textbox._text)
                labelboxes.append(textbox)
                handlebox = DrawingArea(width=self.handlelength*fontsize,
                                        height=height,
                                        xdescent=0., ydescent=descent)
                handlebox.add_artist(handle)
                if isinstance(handle, RegularPolyCollection) or \
                       isinstance(handle, CircleCollection):
                    handle._transOffset = handlebox.get_transform()
                    handle.set_transform(None)
                if hasattr(handle, "_legmarker"):
                    handlebox.add_artist(handle._legmarker)
                handleboxes.append(handlebox)
        if len(handleboxes) > 0:
            ncol = min(self._ncol, len(handleboxes))
            nrows, num_largecol = divmod(len(handleboxes), ncol)
            num_smallcol = ncol-num_largecol
            largecol = safezip(range(0, num_largecol*(nrows+1), (nrows+1)),
                               [nrows+1] * num_largecol)
            smallcol = safezip(range(num_largecol*(nrows+1), len(handleboxes), nrows),
                               [nrows] * num_smallcol)
        else:
            largecol, smallcol = [], []
        handle_label = safezip(handleboxes, labelboxes)
        columnbox = []
        for i0, di in largecol+smallcol:
            itemBoxes = [HPacker(pad=0,
                                 sep=self.handletextpad*fontsize,
                                 children=[h, t], align="baseline")
                         for h, t in handle_label[i0:i0+di]]
            itemBoxes[-1].get_children()[1].set_minimumdescent(False)
            columnbox.append(VPacker(pad=0,
                                        sep=self.labelspacing*fontsize,
                                        align="baseline",
                                        children=itemBoxes))
        if self._mode == "expand":
            mode = "expand"
        else:
            mode = "fixed"
        sep = self.columnspacing*fontsize
        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep, align="baseline",
                                          mode=mode,
                                          children=columnbox)
        self._legend_title_box = TextArea("")
        self._legend_box = VPacker(pad=self.borderpad*fontsize,
                                   sep=self.labelspacing*fontsize,
                                   align="center",
                                   children=[self._legend_title_box,
                                             self._legend_handle_box])
        self._legend_box.set_figure(self.figure)
        self.texts = text_list
        self.legendHandles = handle_list
    def _auto_legend_data(self):
        """
        Returns list of vertices and extents covered by the plot.
        Returns a two long list.
        First element is a list of (x, y) vertices (in
        display-coordinates) covered by all the lines and line
        collections, in the legend's handles.
        Second element is a list of bounding boxes for all the patches in
        the legend's handles.
        """
        assert self.isaxes # should always hold because function is only called internally
        ax = self.parent
        vertices = []
        bboxes = []
        lines = []
        for handle in ax.lines:
            assert isinstance(handle, Line2D)
            path = handle.get_path()
            trans = handle.get_transform()
            tpath = trans.transform_path(path)
            lines.append(tpath)
        for handle in ax.patches:
            assert isinstance(handle, Patch)
            if isinstance(handle, Rectangle):
                transform = handle.get_data_transform()
                bboxes.append(handle.get_bbox().transformed(transform))
            else:
                transform = handle.get_transform()
                bboxes.append(handle.get_path().get_extents(transform))
        return [vertices, bboxes, lines]
    def draw_frame(self, b):
        'b is a boolean.  Set draw frame to b'
        self.set_frame_on(b)
    def get_children(self):
        'return a list of child artists'
        children = []
        if self._legend_box:
            children.append(self._legend_box)
        children.extend(self.get_lines())
        children.extend(self.get_patches())
        children.extend(self.get_texts())
        children.append(self.get_frame())
        if self._legend_title_box:
            children.append(self.get_title())
        return children
    def get_frame(self):
        'return the Rectangle instance used to frame the legend'
        return self.legendPatch
    def get_lines(self):
        'return a list of lines.Line2D instances in the legend'
        return [h for h in self.legendHandles if isinstance(h, Line2D)]
    def get_patches(self):
        'return a list of patch instances in the legend'
        return silent_list('Patch', [h for h in self.legendHandles if isinstance(h, Patch)])
    def get_texts(self):
        'return a list of text.Text instance in the legend'
        return silent_list('Text', self.texts)
    def set_title(self, title):
        'set the legend title'
        self._legend_title_box._text.set_text(title)
        if title:
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box.set_visible(False)
    def get_title(self):
        'return Text instance for the legend title'
        return self._legend_title_box._text
    def get_window_extent(self):
        'return a extent of the the legend'
        return self.legendPatch.get_window_extent()
    def get_frame_on(self):
        """
        Get whether the legend box patch is drawn
        """
        return self._drawFrame
    def set_frame_on(self, b):
        """
        Set whether the legend box patch is drawn
        ACCEPTS: [ *True* | *False* ]
        """
        self._drawFrame = b
    def get_bbox_to_anchor(self):
        """
        return the bbox that the legend will be anchored
        """
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor
    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        set the bbox that the legend will be anchored.
        *bbox* can be a BboxBase instance, a tuple of [left, bottom,
        width, height] in the given transform (normalized axes
        coordinate if None), or a tuple of [left, bottom] where the
        width and height will be assumed to be zero.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError:
                raise ValueError("Invalid argument for bbox : %s" % str(bbox))
            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]
            self._bbox_to_anchor = Bbox.from_bounds(*bbox)
        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)
        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor,
                                               transform)
    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x,y) coordinate of the bbox.
        - loc: a location code in range(1, 11).
          This corresponds to the possible values for self._loc, excluding "best".
        - bbox: bbox to be placed, display coodinate units.
        - parentbbox: a parent box which will contain the bbox. In
            display coordinates.
        """
        assert loc in range(1,11) # called only internally
        BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = range(11)
        anchor_coefs={UR:"NE",
                      UL:"NW",
                      LL:"SW",
                      LR:"SE",
                      R:"E",
                      CL:"W",
                      CR:"E",
                      LC:"S",
                      UC:"N",
                      C:"C"}
        c = anchor_coefs[loc]
        fontsize = renderer.points_to_pixels(self._fontsize)
        container = parentbbox.padded(-(self.borderaxespad) * fontsize)
        anchored_box = bbox.anchored(c, container=container)
        return anchored_box.x0, anchored_box.y0
    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.
        `consider` is a list of (x, y) pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """
        assert self.isaxes # should always hold because function is only called internally
        verts, bboxes, lines = self._auto_legend_data()
        bbox = Bbox.from_bounds(0, 0, width, height)
        consider = [self._get_anchored_bbox(x, bbox, self.get_bbox_to_anchor(),
                                            renderer) for x in range(1, len(self.codes))]
        candidates = []
        for l, b in consider:
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            badness = legendBox.count_contains(verts)
            badness += legendBox.count_overlaps(bboxes)
            for line in lines:
                if line.intersects_bbox(legendBox):
                    badness += 1
            ox, oy = l, b
            if badness == 0:
                return ox, oy
            candidates.append((badness, (l, b)))
        minCandidate = candidates[0]
        for candidate in candidates:
            if candidate[0] < minCandidate[0]:
                minCandidate = candidate
        ox, oy = minCandidate[1]
        return ox, oy
    def draggable(self, state=None, use_blit=False):
        """
        Set the draggable state -- if state is
          * None : toggle the current state
          * True : turn draggable on
          * False : turn draggable off
        If draggable is on, you can drag the legend on the canvas with
        the mouse.  The DraggableLegend helper instance is returned if
        draggable is on.
        """
        is_draggable = self._draggable is not None
        if state is None:
            state = not is_draggable
        if state:
            if self._draggable is None:
                self._draggable = DraggableLegend(self, use_blit)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None
        return self._draggable
Exemple #5
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.
    """

    # 'best' is only implemented for axes legends
    codes = {'best': 0, **AnchoredOffsetbox.codes}
    zorder = 5

    def __str__(self):
        return "Legend"

    @docstring.dedent_interpd
    def __init__(
        self, parent, handles, labels,
        loc=None,
        numpoints=None,      # number of points in the legend line
        markerscale=None,    # relative size of legend markers vs. original
        markerfirst=True,    # left/right ordering of legend marker and label
        scatterpoints=None,  # number of scatter points
        scatteryoffsets=None,
        prop=None,           # properties for the legend texts
        fontsize=None,       # keyword to set font size directly
        labelcolor=None,     # keyword to set the text color

        # spacing & pad defined as a fraction of the font-size
        borderpad=None,      # whitespace inside the legend border
        labelspacing=None,   # vertical space between the legend entries
        handlelength=None,   # length of the legend handles
        handleheight=None,   # height of the legend handles
        handletextpad=None,  # pad between the legend handle and text
        borderaxespad=None,  # pad between the axes and legend border
        columnspacing=None,  # spacing between columns

        ncol=1,     # number of columns
        mode=None,  # horizontal distribution of columns: None or "expand"

        fancybox=None,  # True: fancy box, False: rounded box, None: rcParam
        shadow=None,
        title=None,           # legend title
        title_fontsize=None,  # legend title font size
        framealpha=None,      # set frame alpha
        edgecolor=None,       # frame patch edgecolor
        facecolor=None,       # frame patch facecolor

        bbox_to_anchor=None,  # bbox to which the legend will be anchored
        bbox_transform=None,  # transform for the bbox
        frameon=None,         # draw frame
        handler_map=None,
        title_fontproperties=None,  # properties for the legend title
    ):
        """
        Parameters
        ----------
        parent : `~matplotlib.axes.Axes` or `.Figure`
            The artist that contains the legend.

        handles : list of `.Artist`
            A list of Artists (lines, patches) to be added to the legend.

        labels : list of str
            A list of labels to show next to the artists. The length of handles
            and labels should be the same. If they are not, they are truncated
            to the smaller of both lengths.

        Other Parameters
        ----------------
        %(_legend_kw_doc)s

        Notes
        -----
        Users can specify any arbitrary location for the legend using the
        *bbox_to_anchor* keyword argument. *bbox_to_anchor* can be a
        `.BboxBase` (or derived there from) or a tuple of 2 or 4 floats.
        See `set_bbox_to_anchor` for more detail.

        The legend location can be specified by setting *loc* with a tuple of
        2 floats, which is interpreted as the lower-left corner of the legend
        in the normalized axes coordinate.
        """
        # local import only to avoid circularity
        from matplotlib.axes import Axes
        from matplotlib.figure import FigureBase

        super().__init__()

        if prop is None:
            if fontsize is not None:
                self.prop = FontProperties(size=fontsize)
            else:
                self.prop = FontProperties(
                    size=mpl.rcParams["legend.fontsize"])
        else:
            self.prop = FontProperties._from_any(prop)
            if isinstance(prop, dict) and "size" not in prop:
                self.prop.set_size(mpl.rcParams["legend.fontsize"])

        self._fontsize = self.prop.get_size_in_points()

        self.texts = []
        self.legendHandles = []
        self._legend_title_box = None

        #: A dictionary with the extra handler mappings for this Legend
        #: instance.
        self._custom_handler_map = handler_map

        def val_or_rc(val, rc_name):
            return val if val is not None else mpl.rcParams[rc_name]

        self.numpoints = val_or_rc(numpoints, 'legend.numpoints')
        self.markerscale = val_or_rc(markerscale, 'legend.markerscale')
        self.scatterpoints = val_or_rc(scatterpoints, 'legend.scatterpoints')
        self.borderpad = val_or_rc(borderpad, 'legend.borderpad')
        self.labelspacing = val_or_rc(labelspacing, 'legend.labelspacing')
        self.handlelength = val_or_rc(handlelength, 'legend.handlelength')
        self.handleheight = val_or_rc(handleheight, 'legend.handleheight')
        self.handletextpad = val_or_rc(handletextpad, 'legend.handletextpad')
        self.borderaxespad = val_or_rc(borderaxespad, 'legend.borderaxespad')
        self.columnspacing = val_or_rc(columnspacing, 'legend.columnspacing')
        self.shadow = val_or_rc(shadow, 'legend.shadow')
        # trim handles and labels if illegal label...
        _lab, _hand = [], []
        for label, handle in zip(labels, handles):
            if isinstance(label, str) and label.startswith('_'):
                _api.warn_external('The handle {!r} has a label of {!r} '
                                   'which cannot be automatically added to'
                                   ' the legend.'.format(handle, label))
            else:
                _lab.append(label)
                _hand.append(handle)
        labels, handles = _lab, _hand

        handles = list(handles)
        if len(handles) < 2:
            ncol = 1
        self._ncol = ncol

        if self.numpoints <= 0:
            raise ValueError("numpoints must be > 0; it was %d" % numpoints)

        # introduce y-offset for handles of the scatter plot
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3. / 8., 4. / 8., 2.5 / 8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps = self.scatterpoints // len(self._scatteryoffsets) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets,
                                        reps)[:self.scatterpoints]

        # _legend_box is a VPacker instance that contains all
        # legend items and will be initialized from _init_legend_box()
        # method.
        self._legend_box = None

        if isinstance(parent, Axes):
            self.isaxes = True
            self.axes = parent
            self.set_figure(parent.figure)
        elif isinstance(parent, FigureBase):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError(
                "Legend needs either Axes or FigureBase as parent"
            )
        self.parent = parent

        self._loc_used_default = loc is None
        if loc is None:
            loc = mpl.rcParams["legend.loc"]
            if not self.isaxes and loc in [0, 'best']:
                loc = 'upper right'
        if isinstance(loc, str):
            loc = _api.check_getitem(self.codes, loc=loc)
        if not self.isaxes and loc == 0:
            raise ValueError(
                "Automatic legend placement (loc='best') not implemented for "
                "figure legend")

        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

        # We use FancyBboxPatch to draw a legend frame. The location
        # and size of the box will be updated during the drawing time.

        if facecolor is None:
            facecolor = mpl.rcParams["legend.facecolor"]
        if facecolor == 'inherit':
            facecolor = mpl.rcParams["axes.facecolor"]

        if edgecolor is None:
            edgecolor = mpl.rcParams["legend.edgecolor"]
        if edgecolor == 'inherit':
            edgecolor = mpl.rcParams["axes.edgecolor"]

        if fancybox is None:
            fancybox = mpl.rcParams["legend.fancybox"]

        self.legendPatch = FancyBboxPatch(
            xy=(0, 0), width=1, height=1,
            facecolor=facecolor, edgecolor=edgecolor,
            # If shadow is used, default to alpha=1 (#8943).
            alpha=(framealpha if framealpha is not None
                   else 1 if shadow
                   else mpl.rcParams["legend.framealpha"]),
            # The width and height of the legendPatch will be set (in draw())
            # to the length that includes the padding. Thus we set pad=0 here.
            boxstyle=("round,pad=0,rounding_size=0.2" if fancybox
                      else "square,pad=0"),
            mutation_scale=self._fontsize,
            snap=True,
            visible=(frameon if frameon is not None
                     else mpl.rcParams["legend.frameon"])
        )
        self._set_artist_props(self.legendPatch)

        # init with null renderer
        self._init_legend_box(handles, labels, markerfirst)

        tmp = self._loc_used_default
        self._set_loc(loc)
        self._loc_used_default = tmp  # ignore changes done by _set_loc

        # figure out title font properties:
        if title_fontsize is not None and title_fontproperties is not None:
            raise ValueError(
                "title_fontsize and title_fontproperties can't be specified "
                "at the same time. Only use one of them. ")
        title_prop_fp = FontProperties._from_any(title_fontproperties)
        if isinstance(title_fontproperties, dict):
            if "size" not in title_fontproperties:
                title_fontsize = mpl.rcParams["legend.title_fontsize"]
                title_prop_fp.set_size(title_fontsize)
        elif title_fontsize is not None:
            title_prop_fp.set_size(title_fontsize)
        elif not isinstance(title_fontproperties, FontProperties):
            title_fontsize = mpl.rcParams["legend.title_fontsize"]
            title_prop_fp.set_size(title_fontsize)

        self.set_title(title, prop=title_prop_fp)
        self._draggable = None

        # set the text color

        color_getters = {  # getter function depends on line or patch
            'linecolor':       ['get_color',           'get_facecolor'],
            'markerfacecolor': ['get_markerfacecolor', 'get_facecolor'],
            'mfc':             ['get_markerfacecolor', 'get_facecolor'],
            'markeredgecolor': ['get_markeredgecolor', 'get_edgecolor'],
            'mec':             ['get_markeredgecolor', 'get_edgecolor'],
        }
        if labelcolor is None:
            if mpl.rcParams['legend.labelcolor'] is not None:
                labelcolor = mpl.rcParams['legend.labelcolor']
            else:
                labelcolor = mpl.rcParams['text.color']
        if isinstance(labelcolor, str) and labelcolor in color_getters:
            getter_names = color_getters[labelcolor]
            for handle, text in zip(self.legendHandles, self.texts):
                for getter_name in getter_names:
                    try:
                        color = getattr(handle, getter_name)()
                        text.set_color(color)
                        break
                    except AttributeError:
                        pass
        elif isinstance(labelcolor, str) and labelcolor == 'none':
            for text in self.texts:
                text.set_color(labelcolor)
        elif np.iterable(labelcolor):
            for text, color in zip(self.texts,
                                   itertools.cycle(
                                       colors.to_rgba_array(labelcolor))):
                text.set_color(color)
        else:
            raise ValueError("Invalid argument for labelcolor : %s" %
                             str(labelcolor))

    def _set_artist_props(self, a):
        """
        Set the boilerplate props for artists added to axes.
        """
        a.set_figure(self.figure)
        if self.isaxes:
            # a.set_axes(self.axes)
            a.axes = self.axes

        a.set_transform(self.get_transform())

    def _set_loc(self, loc):
        # find_offset function will be provided to _legend_box and
        # _legend_box will draw itself at the location of the return
        # value of the find_offset.
        self._loc_used_default = False
        self._loc_real = loc
        self.stale = True
        self._legend_box.set_offset(self._findoffset)

    def _get_loc(self):
        return self._loc_real

    _loc = property(_get_loc, _set_loc)

    def _findoffset(self, width, height, xdescent, ydescent, renderer):
        """Helper function to locate the legend."""

        if self._loc == 0:  # "best".
            x, y = self._find_best_position(width, height, renderer)
        elif self._loc in Legend.codes.values():  # Fixed location.
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox,
                                           self.get_bbox_to_anchor(),
                                           renderer)
        else:  # Axes or figure coordinates.
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy

        return x + xdescent, y + ydescent

    @allow_rasterization
    def draw(self, renderer):
        # docstring inherited
        if not self.get_visible():
            return

        renderer.open_group('legend', gid=self.get_gid())

        fontsize = renderer.points_to_pixels(self._fontsize)

        # if mode == fill, set the width of the legend_box to the
        # width of the parent (minus pads)
        if self._mode in ["expand"]:
            pad = 2 * (self.borderaxespad + self.borderpad) * fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width - pad)

        # update the location and size of the legend. This needs to
        # be done in any case to clip the figure right.
        bbox = self._legend_box.get_window_extent(renderer)
        self.legendPatch.set_bounds(bbox.x0, bbox.y0, bbox.width, bbox.height)
        self.legendPatch.set_mutation_scale(fontsize)

        if self.shadow:
            Shadow(self.legendPatch, 2, -2).draw(renderer)

        self.legendPatch.draw(renderer)
        self._legend_box.draw(renderer)

        renderer.close_group('legend')
        self.stale = False

    # _default_handler_map defines the default mapping between plot
    # elements and the legend handlers.

    _default_handler_map = {
        StemContainer: legend_handler.HandlerStem(),
        ErrorbarContainer: legend_handler.HandlerErrorbar(),
        Line2D: legend_handler.HandlerLine2D(),
        Patch: legend_handler.HandlerPatch(),
        StepPatch: legend_handler.HandlerStepPatch(),
        LineCollection: legend_handler.HandlerLineCollection(),
        RegularPolyCollection: legend_handler.HandlerRegularPolyCollection(),
        CircleCollection: legend_handler.HandlerCircleCollection(),
        BarContainer: legend_handler.HandlerPatch(
            update_func=legend_handler.update_from_first_child),
        tuple: legend_handler.HandlerTuple(),
        PathCollection: legend_handler.HandlerPathCollection(),
        PolyCollection: legend_handler.HandlerPolyCollection()
        }

    # (get|set|update)_default_handler_maps are public interfaces to
    # modify the default handler map.

    @classmethod
    def get_default_handler_map(cls):
        """Return the global default handler map, shared by all legends."""
        return cls._default_handler_map

    @classmethod
    def set_default_handler_map(cls, handler_map):
        """Set the global default handler map, shared by all legends."""
        cls._default_handler_map = handler_map

    @classmethod
    def update_default_handler_map(cls, handler_map):
        """Update the global default handler map, shared by all legends."""
        cls._default_handler_map.update(handler_map)

    def get_legend_handler_map(self):
        """Return this legend instance's handler map."""
        default_handler_map = self.get_default_handler_map()
        return ({**default_handler_map, **self._custom_handler_map}
                if self._custom_handler_map else default_handler_map)

    @staticmethod
    def get_legend_handler(legend_handler_map, orig_handle):
        """
        Return a legend handler from *legend_handler_map* that
        corresponds to *orig_handler*.

        *legend_handler_map* should be a dictionary object (that is
        returned by the get_legend_handler_map method).

        It first checks if the *orig_handle* itself is a key in the
        *legend_handler_map* and return the associated value.
        Otherwise, it checks for each of the classes in its
        method-resolution-order. If no matching key is found, it
        returns ``None``.
        """
        try:
            return legend_handler_map[orig_handle]
        except (TypeError, KeyError):  # TypeError if unhashable.
            pass
        for handle_type in type(orig_handle).mro():
            try:
                return legend_handler_map[handle_type]
            except KeyError:
                pass
        return None

    def _init_legend_box(self, handles, labels, markerfirst=True):
        """
        Initialize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """

        fontsize = self._fontsize

        # legend_box is a HPacker, horizontally packed with
        # columns. Each column is a VPacker, vertically packed with
        # legend items. Each legend item is HPacker packed with
        # legend handleBox and labelBox. handleBox is an instance of
        # offsetbox.DrawingArea which contains legend handle. labelBox
        # is an instance of offsetbox.TextArea which contains legend
        # text.

        text_list = []  # the list of text instances
        handle_list = []  # the list of handle instances
        handles_and_labels = []

        label_prop = dict(verticalalignment='baseline',
                          horizontalalignment='left',
                          fontproperties=self.prop,
                          )

        # The approximate height and descent of text. These values are
        # only used for plotting the legend handle.
        descent = 0.35 * fontsize * (self.handleheight - 0.7)
        # 0.35 and 0.7 are just heuristic numbers and may need to be improved.
        height = fontsize * self.handleheight - descent
        # each handle needs to be drawn inside a box of (x, y, w, h) =
        # (0, -descent, width, height).  And their coordinates should
        # be given in the display coordinates.

        # The transformation of each handle will be automatically set
        # to self.get_transform(). If the artist does not use its
        # default transform (e.g., Collections), you need to
        # manually set their transform to the self.get_transform().
        legend_handler_map = self.get_legend_handler_map()

        for orig_handle, lab in zip(handles, labels):
            handler = self.get_legend_handler(legend_handler_map, orig_handle)
            if handler is None:
                _api.warn_external(
                    "Legend does not support {!r} instances.\nA proxy artist "
                    "may be used instead.\nSee: "
                    "https://matplotlib.org/users/legend_guide.html"
                    "#creating-artists-specifically-for-adding-to-the-legend-"
                    "aka-proxy-artists".format(orig_handle))
                # We don't have a handle for this artist, so we just defer
                # to None.
                handle_list.append(None)
            else:
                textbox = TextArea(lab, textprops=label_prop,
                                   multilinebaseline=True)
                handlebox = DrawingArea(width=self.handlelength * fontsize,
                                        height=height,
                                        xdescent=0., ydescent=descent)

                text_list.append(textbox._text)
                # Create the artist for the legend which represents the
                # original artist/handle.
                handle_list.append(handler.legend_artist(self, orig_handle,
                                                         fontsize, handlebox))
                handles_and_labels.append((handlebox, textbox))

        if handles_and_labels:
            # We calculate number of rows in each column. The first
            # (num_largecol) columns will have (nrows+1) rows, and remaining
            # (num_smallcol) columns will have (nrows) rows.
            ncol = min(self._ncol, len(handles_and_labels))
            nrows, num_largecol = divmod(len(handles_and_labels), ncol)
            num_smallcol = ncol - num_largecol
            # starting index of each column and number of rows in it.
            rows_per_col = [nrows + 1] * num_largecol + [nrows] * num_smallcol
            start_idxs = np.concatenate([[0], np.cumsum(rows_per_col)[:-1]])
            cols = zip(start_idxs, rows_per_col)
        else:
            cols = []

        columnbox = []
        for i0, di in cols:
            # pack handleBox and labelBox into itemBox
            itemBoxes = [HPacker(pad=0,
                                 sep=self.handletextpad * fontsize,
                                 children=[h, t] if markerfirst else [t, h],
                                 align="baseline")
                         for h, t in handles_and_labels[i0:i0 + di]]
            # pack columnBox
            alignment = "baseline" if markerfirst else "right"
            columnbox.append(VPacker(pad=0,
                                     sep=self.labelspacing * fontsize,
                                     align=alignment,
                                     children=itemBoxes))

        mode = "expand" if self._mode == "expand" else "fixed"
        sep = self.columnspacing * fontsize
        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep, align="baseline",
                                          mode=mode,
                                          children=columnbox)
        self._legend_title_box = TextArea("")
        self._legend_box = VPacker(pad=self.borderpad * fontsize,
                                   sep=self.labelspacing * fontsize,
                                   align="center",
                                   children=[self._legend_title_box,
                                             self._legend_handle_box])
        self._legend_box.set_figure(self.figure)
        self._legend_box.axes = self.axes
        self.texts = text_list
        self.legendHandles = handle_list

    def _auto_legend_data(self):
        """
        Return display coordinates for hit testing for "best" positioning.

        Returns
        -------
        bboxes
            List of bounding boxes of all patches.
        lines
            List of `.Path` corresponding to each line.
        offsets
            List of (x, y) offsets of all collection.
        """
        assert self.isaxes  # always holds, as this is only called internally
        bboxes = []
        lines = []
        offsets = []
        for artist in self.parent._children:
            if isinstance(artist, Line2D):
                lines.append(
                    artist.get_transform().transform_path(artist.get_path()))
            elif isinstance(artist, Rectangle):
                bboxes.append(
                    artist.get_bbox().transformed(artist.get_data_transform()))
            elif isinstance(artist, Patch):
                bboxes.append(
                    artist.get_path().get_extents(artist.get_transform()))
            elif isinstance(artist, Collection):
                _, transOffset, hoffsets, _ = artist._prepare_points()
                for offset in transOffset.transform(hoffsets):
                    offsets.append(offset)
        return bboxes, lines, offsets

    def get_children(self):
        # docstring inherited
        return [self._legend_box, self.get_frame()]

    def get_frame(self):
        """Return the `~.patches.Rectangle` used to frame the legend."""
        return self.legendPatch

    def get_lines(self):
        r"""Return the list of `~.lines.Line2D`\s in the legend."""
        return [h for h in self.legendHandles if isinstance(h, Line2D)]

    def get_patches(self):
        r"""Return the list of `~.patches.Patch`\s in the legend."""
        return silent_list('Patch',
                           [h for h in self.legendHandles
                            if isinstance(h, Patch)])

    def get_texts(self):
        r"""Return the list of `~.text.Text`\s in the legend."""
        return silent_list('Text', self.texts)

    def set_title(self, title, prop=None):
        """
        Set the legend title. Fontproperties can be optionally set
        with *prop* parameter.
        """
        self._legend_title_box._text.set_text(title)
        if title:
            self._legend_title_box._text.set_visible(True)
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box._text.set_visible(False)
            self._legend_title_box.set_visible(False)

        if prop is not None:
            self._legend_title_box._text.set_fontproperties(prop)

        self.stale = True

    def get_title(self):
        """Return the `.Text` instance for the legend title."""
        return self._legend_title_box._text

    def get_window_extent(self, renderer=None):
        # docstring inherited
        if renderer is None:
            renderer = self.figure._cachedRenderer
        return self._legend_box.get_window_extent(renderer=renderer)

    def get_tightbbox(self, renderer):
        """
        Like `.Legend.get_window_extent`, but uses the box for the legend.

        Parameters
        ----------
        renderer : `.RendererBase` subclass
            renderer that will be used to draw the figures (i.e.
            ``fig.canvas.get_renderer()``)

        Returns
        -------
        `.BboxBase`
            The bounding box in figure pixel coordinates.
        """
        return self._legend_box.get_window_extent(renderer)

    def get_frame_on(self):
        """Get whether the legend box patch is drawn."""
        return self.legendPatch.get_visible()

    def set_frame_on(self, b):
        """
        Set whether the legend box patch is drawn.

        Parameters
        ----------
        b : bool
        """
        self.legendPatch.set_visible(b)
        self.stale = True

    draw_frame = set_frame_on  # Backcompat alias.

    def get_bbox_to_anchor(self):
        """Return the bbox that the legend will be anchored to."""
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor

    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        Set the bbox that the legend will be anchored to.

        Parameters
        ----------
        bbox : `~matplotlib.transforms.BboxBase` or tuple
            The bounding box can be specified in the following ways:

            - A `.BboxBase` instance
            - A tuple of ``(left, bottom, width, height)`` in the given
              transform (normalized axes coordinate if None)
            - A tuple of ``(left, bottom)`` where the width and height will be
              assumed to be zero.
            - *None*, to remove the bbox anchoring, and use the parent bbox.

        transform : `~matplotlib.transforms.Transform`, optional
            A transform to apply to the bounding box. If not specified, this
            will use a transform to the bounding box of the parent.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError as err:
                raise ValueError("Invalid argument for bbox : %s" %
                                 str(bbox)) from err

            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]

            self._bbox_to_anchor = Bbox.from_bounds(*bbox)

        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)

        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor,
                                               transform)
        self.stale = True

    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x, y) coordinate of the bbox.

        Parameters
        ----------
        loc : int
            A location code in range(1, 11). This corresponds to the possible
            values for ``self._loc``, excluding "best".
        bbox : `~matplotlib.transforms.Bbox`
            bbox to be placed, in display coordinates.
        parentbbox : `~matplotlib.transforms.Bbox`
            A parent box which will contain the bbox, in display coordinates.
        """
        return offsetbox._get_anchored_bbox(
            loc, bbox, parentbbox,
            self.borderaxespad * renderer.points_to_pixels(self._fontsize))

    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.

        *consider* is a list of ``(x, y)`` pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """
        assert self.isaxes  # always holds, as this is only called internally

        start_time = time.perf_counter()

        bboxes, lines, offsets = self._auto_legend_data()

        bbox = Bbox.from_bounds(0, 0, width, height)
        if consider is None:
            consider = [self._get_anchored_bbox(x, bbox,
                                                self.get_bbox_to_anchor(),
                                                renderer)
                        for x in range(1, len(self.codes))]

        candidates = []
        for idx, (l, b) in enumerate(consider):
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            # XXX TODO: If markers are present, it would be good to take them
            # into account when checking vertex overlaps in the next line.
            badness = (sum(legendBox.count_contains(line.vertices)
                           for line in lines)
                       + legendBox.count_contains(offsets)
                       + legendBox.count_overlaps(bboxes)
                       + sum(line.intersects_bbox(legendBox, filled=False)
                             for line in lines))
            if badness == 0:
                return l, b
            # Include the index to favor lower codes in case of a tie.
            candidates.append((badness, idx, (l, b)))

        _, _, (l, b) = min(candidates)

        if self._loc_used_default and time.perf_counter() - start_time > 1:
            _api.warn_external(
                'Creating legend with loc="best" can be slow with large '
                'amounts of data.')

        return l, b

    def contains(self, event):
        inside, info = self._default_contains(event)
        if inside is not None:
            return inside, info
        return self.legendPatch.contains(event)

    def set_draggable(self, state, use_blit=False, update='loc'):
        """
        Enable or disable mouse dragging support of the legend.

        Parameters
        ----------
        state : bool
            Whether mouse dragging is enabled.
        use_blit : bool, optional
            Use blitting for faster image composition. For details see
            :ref:`func-animation`.
        update : {'loc', 'bbox'}, optional
            The legend parameter to be changed when dragged:

            - 'loc': update the *loc* parameter of the legend
            - 'bbox': update the *bbox_to_anchor* parameter of the legend

        Returns
        -------
        `.DraggableLegend` or *None*
            If *state* is ``True`` this returns the `.DraggableLegend` helper
            instance. Otherwise this returns *None*.
        """
        if state:
            if self._draggable is None:
                self._draggable = DraggableLegend(self,
                                                  use_blit,
                                                  update=update)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None
        return self._draggable

    def get_draggable(self):
        """Return ``True`` if the legend is draggable, ``False`` otherwise."""
        return self._draggable is not None
Exemple #6
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.  Labels are a
    sequence of strings and loc can be a string or an integer
    specifying the legend location

    The location codes are::

      'best'         : 0, (only implemented for axes legends)
      'upper right'  : 1,
      'upper left'   : 2,
      'lower left'   : 3,
      'lower right'  : 4,
      'right'        : 5, (same as 'center right', for back-compatibility)
      'center left'  : 6,
      'center right' : 7,
      'lower center' : 8,
      'upper center' : 9,
      'center'       : 10,

    loc can be a tuple of the normalized coordinate values with
    respect its parent.

    """
    codes = {'best':         0,  # only implemented for axes legends
             'upper right':  1,
             'upper left':   2,
             'lower left':   3,
             'lower right':  4,
             'right':        5,
             'center left':  6,
             'center right': 7,
             'lower center': 8,
             'upper center': 9,
             'center':       10,
             }

    zorder = 5

    def __str__(self):
        return "Legend"

    def __init__(self, parent, handles, labels,
                 loc=None,
                 numpoints=None,    # the number of points in the legend line
                 markerscale=None,  # the relative size of legend markers
                                    # vs. original
                 markerfirst=True,  # controls ordering (left-to-right) of
                                    # legend marker and label
                 scatterpoints=None,    # number of scatter points
                 scatteryoffsets=None,
                 prop=None,          # properties for the legend texts
                 fontsize=None,        # keyword to set font size directly

                 # spacing & pad defined as a fraction of the font-size
                 borderpad=None,      # the whitespace inside the legend border
                 labelspacing=None,   # the vertical space between the legend
                                      # entries
                 handlelength=None,   # the length of the legend handles
                 handleheight=None,   # the height of the legend handles
                 handletextpad=None,  # the pad between the legend handle
                                      # and text
                 borderaxespad=None,  # the pad between the axes and legend
                                      # border
                 columnspacing=None,  # spacing between columns

                 ncol=1,     # number of columns
                 mode=None,  # mode for horizontal distribution of columns.
                             # None, "expand"

                 fancybox=None,  # True use a fancy box, false use a rounded
                                 # box, none use rc
                 shadow=None,
                 title=None,  # set a title for the legend

                 framealpha=None,  # set frame alpha
                 edgecolor=None,  # frame patch edgecolor
                 facecolor=None,  # frame patch facecolor

                 bbox_to_anchor=None,  # bbox that the legend will be anchored.
                 bbox_transform=None,  # transform for the bbox
                 frameon=None,  # draw frame
                 handler_map=None,
                 ):
        """
        - *parent*: the artist that contains the legend
        - *handles*: a list of artists (lines, patches) to be added to the
                      legend
        - *labels*: a list of strings to label the legend

        Optional keyword arguments:

        ================   ====================================================
        Keyword            Description
        ================   ====================================================
        loc                Location code string, or tuple (see below).
        prop               the font property
        fontsize           the font size (used only if prop is not specified)
        markerscale        the relative size of legend markers vs. original
        markerfirst        If True (default), marker is to left of the label.
        numpoints          the number of points in the legend for line
        scatterpoints      the number of points in the legend for scatter plot
        scatteryoffsets    a list of yoffsets for scatter symbols in legend
        frameon            If True, draw the legend on a patch (frame).
        fancybox           If True, draw the frame with a round fancybox.
        shadow             If True, draw a shadow behind legend.
        framealpha         Transparency of the frame.
        edgecolor          Frame edgecolor.
        facecolor          Frame facecolor.
        ncol               number of columns
        borderpad          the fractional whitespace inside the legend border
        labelspacing       the vertical space between the legend entries
        handlelength       the length of the legend handles
        handleheight       the height of the legend handles
        handletextpad      the pad between the legend handle and text
        borderaxespad      the pad between the axes and legend border
        columnspacing      the spacing between columns
        title              the legend title
        bbox_to_anchor     the bbox that the legend will be anchored.
        bbox_transform     the transform for the bbox. transAxes if None.
        ================   ====================================================


        The pad and spacing parameters are measured in font-size units.  e.g.,
        a fontsize of 10 points and a handlelength=5 implies a handlelength of
        50 points.  Values from rcParams will be used if None.

        Users can specify any arbitrary location for the legend using the
        *bbox_to_anchor* keyword argument. bbox_to_anchor can be an instance
        of BboxBase(or its derivatives) or a tuple of 2 or 4 floats.
        See :meth:`set_bbox_to_anchor` for more detail.

        The legend location can be specified by setting *loc* with a tuple of
        2 floats, which is interpreted as the lower-left corner of the legend
        in the normalized axes coordinate.
        """
        # local import only to avoid circularity
        from matplotlib.axes import Axes
        from matplotlib.figure import Figure

        Artist.__init__(self)

        if prop is None:
            if fontsize is not None:
                self.prop = FontProperties(size=fontsize)
            else:
                self.prop = FontProperties(size=rcParams["legend.fontsize"])
        elif isinstance(prop, dict):
            self.prop = FontProperties(**prop)
            if "size" not in prop:
                self.prop.set_size(rcParams["legend.fontsize"])
        else:
            self.prop = prop

        self._fontsize = self.prop.get_size_in_points()

        self.texts = []
        self.legendHandles = []
        self._legend_title_box = None

        #: A dictionary with the extra handler mappings for this Legend
        #: instance.
        self._custom_handler_map = handler_map

        locals_view = locals()
        for name in ["numpoints", "markerscale", "shadow", "columnspacing",
                     "scatterpoints", "handleheight", 'borderpad',
                     'labelspacing', 'handlelength', 'handletextpad',
                     'borderaxespad']:
            if locals_view[name] is None:
                value = rcParams["legend." + name]
            else:
                value = locals_view[name]
            setattr(self, name, value)
        del locals_view

        handles = list(handles)
        if len(handles) < 2:
            ncol = 1
        self._ncol = ncol

        if self.numpoints <= 0:
            raise ValueError("numpoints must be > 0; it was %d" % numpoints)

        # introduce y-offset for handles of the scatter plot
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3. / 8., 4. / 8., 2.5 / 8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps = int(self.scatterpoints / len(self._scatteryoffsets)) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets,
                                        reps)[:self.scatterpoints]

        # _legend_box is an OffsetBox instance that contains all
        # legend items and will be initialized from _init_legend_box()
        # method.
        self._legend_box = None

        if isinstance(parent, Axes):
            self.isaxes = True
            self.axes = parent
            self.set_figure(parent.figure)
        elif isinstance(parent, Figure):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError("Legend needs either Axes or Figure as parent")
        self.parent = parent

        if loc is None:
            loc = rcParams["legend.loc"]
            if not self.isaxes and loc in [0, 'best']:
                loc = 'upper right'
        if isinstance(loc, six.string_types):
            if loc not in self.codes:
                if self.isaxes:
                    warnings.warn('Unrecognized location "%s". Falling back '
                                  'on "best"; valid locations are\n\t%s\n'
                                  % (loc, '\n\t'.join(self.codes)))
                    loc = 0
                else:
                    warnings.warn('Unrecognized location "%s". Falling back '
                                  'on "upper right"; '
                                  'valid locations are\n\t%s\n'
                                  % (loc, '\n\t'.join(self.codes)))
                    loc = 1
            else:
                loc = self.codes[loc]
        if not self.isaxes and loc == 0:
            warnings.warn('Automatic legend placement (loc="best") not '
                          'implemented for figure legend. '
                          'Falling back on "upper right".')
            loc = 1

        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

        # We use FancyBboxPatch to draw a legend frame. The location
        # and size of the box will be updated during the drawing time.

        if facecolor is None:
            facecolor = rcParams["legend.facecolor"]
        if facecolor == 'inherit':
            facecolor = rcParams["axes.facecolor"]

        if edgecolor is None:
            edgecolor = rcParams["legend.edgecolor"]
        if edgecolor == 'inherit':
            edgecolor = rcParams["axes.edgecolor"]

        self.legendPatch = FancyBboxPatch(
            xy=(0.0, 0.0), width=1., height=1.,
            facecolor=facecolor,
            edgecolor=edgecolor,
            mutation_scale=self._fontsize,
            snap=True
            )

        # The width and height of the legendPatch will be set (in the
        # draw()) to the length that includes the padding. Thus we set
        # pad=0 here.
        if fancybox is None:
            fancybox = rcParams["legend.fancybox"]

        if fancybox:
            self.legendPatch.set_boxstyle("round", pad=0,
                                          rounding_size=0.2)
        else:
            self.legendPatch.set_boxstyle("square", pad=0)

        self._set_artist_props(self.legendPatch)

        self._drawFrame = frameon
        if frameon is None:
            self._drawFrame = rcParams["legend.frameon"]

        # init with null renderer
        self._init_legend_box(handles, labels, markerfirst)

        if framealpha is None:
            self.get_frame().set_alpha(rcParams["legend.framealpha"])
        else:
            self.get_frame().set_alpha(framealpha)

        self._loc = loc
        self.set_title(title)
        self._last_fontsize_points = self._fontsize
        self._draggable = None

    def _set_artist_props(self, a):
        """
        set the boilerplate props for artists added to axes
        """
        a.set_figure(self.figure)
        if self.isaxes:
            # a.set_axes(self.axes)
            a.axes = self.axes

        a.set_transform(self.get_transform())

    def _set_loc(self, loc):
        # find_offset function will be provided to _legend_box and
        # _legend_box will draw itself at the location of the return
        # value of the find_offset.
        self._loc_real = loc
        self.stale = True

    def _get_loc(self):
        return self._loc_real

    _loc = property(_get_loc, _set_loc)

    def _findoffset(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend"

        if self._loc == 0:  # "best".
            x, y = self._find_best_position(width, height, renderer)
        elif self._loc in Legend.codes.values():  # Fixed location.
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox,
                                           self.get_bbox_to_anchor(),
                                           renderer)
        else:  # Axes or figure coordinates.
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy

        return x + xdescent, y + ydescent

    @allow_rasterization
    def draw(self, renderer):
        "Draw everything that belongs to the legend"
        if not self.get_visible():
            return

        renderer.open_group('legend')

        fontsize = renderer.points_to_pixels(self._fontsize)

        # if mode == fill, set the width of the legend_box to the
        # width of the paret (minus pads)
        if self._mode in ["expand"]:
            pad = 2 * (self.borderaxespad + self.borderpad) * fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width - pad)

        # update the location and size of the legend. This needs to
        # be done in any case to clip the figure right.
        bbox = self._legend_box.get_window_extent(renderer)
        self.legendPatch.set_bounds(bbox.x0, bbox.y0,
                                    bbox.width, bbox.height)
        self.legendPatch.set_mutation_scale(fontsize)

        if self._drawFrame:
            if self.shadow:
                shadow = Shadow(self.legendPatch, 2, -2)
                shadow.draw(renderer)

            self.legendPatch.draw(renderer)

        self._legend_box.draw(renderer)

        renderer.close_group('legend')
        self.stale = False

    def _approx_text_height(self, renderer=None):
        """
        Return the approximate height of the text. This is used to place
        the legend handle.
        """
        if renderer is None:
            return self._fontsize
        else:
            return renderer.points_to_pixels(self._fontsize)

    # _default_handler_map defines the default mapping between plot
    # elements and the legend handlers.

    _default_handler_map = {
        StemContainer: legend_handler.HandlerStem(),
        ErrorbarContainer: legend_handler.HandlerErrorbar(),
        Line2D: legend_handler.HandlerLine2D(),
        Patch: legend_handler.HandlerPatch(),
        LineCollection: legend_handler.HandlerLineCollection(),
        RegularPolyCollection: legend_handler.HandlerRegularPolyCollection(),
        CircleCollection: legend_handler.HandlerCircleCollection(),
        BarContainer: legend_handler.HandlerPatch(
            update_func=legend_handler.update_from_first_child),
        tuple: legend_handler.HandlerTuple(),
        PathCollection: legend_handler.HandlerPathCollection(),
        PolyCollection: legend_handler.HandlerPolyCollection()
        }

    # (get|set|update)_default_handler_maps are public interfaces to
    # modify the default handler map.

    @classmethod
    def get_default_handler_map(cls):
        """
        A class method that returns the default handler map.
        """
        return cls._default_handler_map

    @classmethod
    def set_default_handler_map(cls, handler_map):
        """
        A class method to set the default handler map.
        """
        cls._default_handler_map = handler_map

    @classmethod
    def update_default_handler_map(cls, handler_map):
        """
        A class method to update the default handler map.
        """
        cls._default_handler_map.update(handler_map)

    def get_legend_handler_map(self):
        """
        return the handler map.
        """

        default_handler_map = self.get_default_handler_map()

        if self._custom_handler_map:
            hm = default_handler_map.copy()
            hm.update(self._custom_handler_map)
            return hm
        else:
            return default_handler_map

    @staticmethod
    def get_legend_handler(legend_handler_map, orig_handle):
        """
        return a legend handler from *legend_handler_map* that
        corresponds to *orig_handler*.

        *legend_handler_map* should be a dictionary object (that is
        returned by the get_legend_handler_map method).

        It first checks if the *orig_handle* itself is a key in the
        *legend_hanler_map* and return the associated value.
        Otherwise, it checks for each of the classes in its
        method-resolution-order. If no matching key is found, it
        returns None.
        """
        if is_hashable(orig_handle):
            try:
                return legend_handler_map[orig_handle]
            except KeyError:
                pass

        for handle_type in type(orig_handle).mro():
            try:
                return legend_handler_map[handle_type]
            except KeyError:
                pass

        return None

    def _init_legend_box(self, handles, labels, markerfirst=True):
        """
        Initialize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """

        fontsize = self._fontsize

        # legend_box is a HPacker, horizontally packed with
        # columns. Each column is a VPacker, vertically packed with
        # legend items. Each legend item is HPacker packed with
        # legend handleBox and labelBox. handleBox is an instance of
        # offsetbox.DrawingArea which contains legend handle. labelBox
        # is an instance of offsetbox.TextArea which contains legend
        # text.

        text_list = []  # the list of text instances
        handle_list = []  # the list of text instances

        label_prop = dict(verticalalignment='baseline',
                          horizontalalignment='left',
                          fontproperties=self.prop,
                          )

        labelboxes = []
        handleboxes = []

        # The approximate height and descent of text. These values are
        # only used for plotting the legend handle.
        descent = 0.35 * self._approx_text_height() * (self.handleheight - 0.7)
        # 0.35 and 0.7 are just heuristic numbers and may need to be improved.
        height = self._approx_text_height() * self.handleheight - descent
        # each handle needs to be drawn inside a box of (x, y, w, h) =
        # (0, -descent, width, height).  And their coordinates should
        # be given in the display coordinates.

        # The transformation of each handle will be automatically set
        # to self.get_trasnform(). If the artist does not use its
        # default transform (e.g., Collections), you need to
        # manually set their transform to the self.get_transform().
        legend_handler_map = self.get_legend_handler_map()

        for orig_handle, lab in zip(handles, labels):
            handler = self.get_legend_handler(legend_handler_map, orig_handle)
            if handler is None:
                warnings.warn(
                    "Legend does not support {!r} instances.\nA proxy artist "
                    "may be used instead.\nSee: "
                    "http://matplotlib.org/users/legend_guide.html"
                    "#using-proxy-artist".format(orig_handle)
                )
                # We don't have a handle for this artist, so we just defer
                # to None.
                handle_list.append(None)
            else:
                textbox = TextArea(lab, textprops=label_prop,
                                   multilinebaseline=True,
                                   minimumdescent=True)
                text_list.append(textbox._text)

                labelboxes.append(textbox)

                handlebox = DrawingArea(width=self.handlelength * fontsize,
                                        height=height,
                                        xdescent=0., ydescent=descent)
                handleboxes.append(handlebox)

                # Create the artist for the legend which represents the
                # original artist/handle.
                handle_list.append(handler.legend_artist(self, orig_handle,
                                                         fontsize, handlebox))

        if handleboxes:
            # We calculate number of rows in each column. The first
            # (num_largecol) columns will have (nrows+1) rows, and remaining
            # (num_smallcol) columns will have (nrows) rows.
            ncol = min(self._ncol, len(handleboxes))
            nrows, num_largecol = divmod(len(handleboxes), ncol)
            num_smallcol = ncol - num_largecol
            # starting index of each column and number of rows in it.
            rows_per_col = [nrows + 1] * num_largecol + [nrows] * num_smallcol
            start_idxs = np.concatenate([[0], np.cumsum(rows_per_col)[:-1]])
            cols = zip(start_idxs, rows_per_col)
        else:
            cols = []

        handle_label = list(zip(handleboxes, labelboxes))
        columnbox = []
        for i0, di in cols:
            # pack handleBox and labelBox into itemBox
            itemBoxes = [HPacker(pad=0,
                                 sep=self.handletextpad * fontsize,
                                 children=[h, t] if markerfirst else [t, h],
                                 align="baseline")
                         for h, t in handle_label[i0:i0 + di]]
            # minimumdescent=False for the text of the last row of the column
            if markerfirst:
                itemBoxes[-1].get_children()[1].set_minimumdescent(False)
            else:
                itemBoxes[-1].get_children()[0].set_minimumdescent(False)

            # pack columnBox
            alignment = "baseline" if markerfirst else "right"
            columnbox.append(VPacker(pad=0,
                                     sep=self.labelspacing * fontsize,
                                     align=alignment,
                                     children=itemBoxes))

        mode = "expand" if self._mode == "expand" else "fixed"
        sep = self.columnspacing * fontsize
        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep, align="baseline",
                                          mode=mode,
                                          children=columnbox)
        self._legend_title_box = TextArea("")
        self._legend_box = VPacker(pad=self.borderpad * fontsize,
                                   sep=self.labelspacing * fontsize,
                                   align="center",
                                   children=[self._legend_title_box,
                                             self._legend_handle_box])
        self._legend_box.set_figure(self.figure)
        self._legend_box.set_offset(self._findoffset)
        self.texts = text_list
        self.legendHandles = handle_list

    def _auto_legend_data(self):
        """
        Returns list of vertices and extents covered by the plot.

        Returns a two long list.

        First element is a list of (x, y) vertices (in
        display-coordinates) covered by all the lines and line
        collections, in the legend's handles.

        Second element is a list of bounding boxes for all the patches in
        the legend's handles.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        ax = self.parent
        bboxes = []
        lines = []
        offsets = []

        for handle in ax.lines:
            assert isinstance(handle, Line2D)
            path = handle.get_path()
            trans = handle.get_transform()
            tpath = trans.transform_path(path)
            lines.append(tpath)

        for handle in ax.patches:
            assert isinstance(handle, Patch)

            if isinstance(handle, Rectangle):
                transform = handle.get_data_transform()
                bboxes.append(handle.get_bbox().transformed(transform))
            else:
                transform = handle.get_transform()
                bboxes.append(handle.get_path().get_extents(transform))

        for handle in ax.collections:
            transform, transOffset, hoffsets, paths = handle._prepare_points()

            if len(hoffsets):
                for offset in transOffset.transform(hoffsets):
                    offsets.append(offset)

        try:
            vertices = np.concatenate([l.vertices for l in lines])
        except ValueError:
            vertices = np.array([])

        return [vertices, bboxes, lines, offsets]

    def draw_frame(self, b):
        'b is a boolean.  Set draw frame to b'
        self.set_frame_on(b)

    def get_children(self):
        'return a list of child artists'
        children = []
        if self._legend_box:
            children.append(self._legend_box)
        children.append(self.get_frame())

        return children

    def get_frame(self):
        'return the Rectangle instance used to frame the legend'
        return self.legendPatch

    def get_lines(self):
        'return a list of lines.Line2D instances in the legend'
        return [h for h in self.legendHandles if isinstance(h, Line2D)]

    def get_patches(self):
        'return a list of patch instances in the legend'
        return silent_list('Patch',
                           [h for h in self.legendHandles
                            if isinstance(h, Patch)])

    def get_texts(self):
        'return a list of text.Text instance in the legend'
        return silent_list('Text', self.texts)

    def set_title(self, title, prop=None):
        """
        set the legend title. Fontproperties can be optionally set
        with *prop* parameter.
        """
        self._legend_title_box._text.set_text(title)

        if prop is not None:
            if isinstance(prop, dict):
                prop = FontProperties(**prop)
            self._legend_title_box._text.set_fontproperties(prop)

        if title:
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box.set_visible(False)
        self.stale = True

    def get_title(self):
        'return Text instance for the legend title'
        return self._legend_title_box._text

    def get_window_extent(self, *args, **kwargs):
        'return a extent of the legend'
        return self.legendPatch.get_window_extent(*args, **kwargs)

    def get_frame_on(self):
        """
        Get whether the legend box patch is drawn
        """
        return self._drawFrame

    def set_frame_on(self, b):
        """
        Set whether the legend box patch is drawn

        ACCEPTS: [ *True* | *False* ]
        """
        self._drawFrame = b
        self.stale = True

    def get_bbox_to_anchor(self):
        """
        return the bbox that the legend will be anchored
        """
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor

    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        set the bbox that the legend will be anchored.

        *bbox* can be a BboxBase instance, a tuple of [left, bottom,
        width, height] in the given transform (normalized axes
        coordinate if None), or a tuple of [left, bottom] where the
        width and height will be assumed to be zero.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError:
                raise ValueError("Invalid argument for bbox : %s" % str(bbox))

            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]

            self._bbox_to_anchor = Bbox.from_bounds(*bbox)

        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)

        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor,
                                               transform)
        self.stale = True

    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x,y) coordinate of the bbox.

        - loc: a location code in range(1, 11).
          This corresponds to the possible values for self._loc, excluding
          "best".

        - bbox: bbox to be placed, display coodinate units.
        - parentbbox: a parent box which will contain the bbox. In
            display coordinates.
        """
        assert loc in range(1, 11)  # called only internally

        BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = list(xrange(11))

        anchor_coefs = {UR: "NE",
                        UL: "NW",
                        LL: "SW",
                        LR: "SE",
                        R: "E",
                        CL: "W",
                        CR: "E",
                        LC: "S",
                        UC: "N",
                        C: "C"}

        c = anchor_coefs[loc]

        fontsize = renderer.points_to_pixels(self._fontsize)
        container = parentbbox.padded(-(self.borderaxespad) * fontsize)
        anchored_box = bbox.anchored(c, container=container)
        return anchored_box.x0, anchored_box.y0

    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.

        `consider` is a list of (x, y) pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        verts, bboxes, lines, offsets = self._auto_legend_data()

        bbox = Bbox.from_bounds(0, 0, width, height)
        if consider is None:
            consider = [self._get_anchored_bbox(x, bbox,
                                                self.get_bbox_to_anchor(),
                                                renderer)
                        for x in range(1, len(self.codes))]

        candidates = []
        for idx, (l, b) in enumerate(consider):
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            # XXX TODO: If markers are present, it would be good to
            # take them into account when checking vertex overlaps in
            # the next line.
            badness = (legendBox.count_contains(verts)
                       + legendBox.count_contains(offsets)
                       + legendBox.count_overlaps(bboxes)
                       + sum(line.intersects_bbox(legendBox, filled=False)
                             for line in lines))
            if badness == 0:
                return l, b
            # Include the index to favor lower codes in case of a tie.
            candidates.append((badness, idx, (l, b)))

        _, _, (l, b) = min(candidates)
        return l, b

    def contains(self, event):
        return self.legendPatch.contains(event)

    def draggable(self, state=None, use_blit=False, update="loc"):
        """
        Set the draggable state -- if state is

          * None : toggle the current state

          * True : turn draggable on

          * False : turn draggable off

        If draggable is on, you can drag the legend on the canvas with
        the mouse.  The DraggableLegend helper instance is returned if
        draggable is on.

        The update parameter control which parameter of the legend changes
        when dragged. If update is "loc", the *loc* parameter of the legend
        is changed. If "bbox", the *bbox_to_anchor* parameter is changed.
        """
        is_draggable = self._draggable is not None

        # if state is None we'll toggle
        if state is None:
            state = not is_draggable

        if state:
            if self._draggable is None:
                self._draggable = DraggableLegend(self,
                                                  use_blit,
                                                  update=update)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None

        return self._draggable
Exemple #7
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.  Labels are a
    sequence of strings and loc can be a string or an integer
    specifying the legend location

    The location codes are::

      'best'         : 0, (only implemented for axis legends)
      'upper right'  : 1,
      'upper left'   : 2,
      'lower left'   : 3,
      'lower right'  : 4,
      'right'        : 5,
      'center left'  : 6,
      'center right' : 7,
      'lower center' : 8,
      'upper center' : 9,
      'center'       : 10,

    loc can be a tuple of the noramilzed coordinate values with
    respect its parent.

    Return value is a sequence of text, line instances that make
    up the legend
    """


    codes = {'best'         : 0, # only implemented for axis legends
             'upper right'  : 1,
             'upper left'   : 2,
             'lower left'   : 3,
             'lower right'  : 4,
             'right'        : 5,
             'center left'  : 6,
             'center right' : 7,
             'lower center' : 8,
             'upper center' : 9,
             'center'       : 10,
             }


    zorder = 5
    def __str__(self):
        return "Legend"

    def __init__(self, parent, handles, labels,
                 loc = None,
                 numpoints = None,     # the number of points in the legend line
                 markerscale = None,   # the relative size of legend markers vs. original
                 scatterpoints = 3,    # TODO: may be an rcParam
                 scatteryoffsets=None,
                 prop = None,          # properties for the legend texts

                 # the following dimensions are in axes coords
                 pad = None,           # deprecated; use borderpad
                 labelsep = None,      # deprecated; use labelspacing
                 handlelen = None,     # deprecated; use handlelength
                 handletextsep = None, # deprecated; use handletextpad
                 axespad = None,       # deprecated; use borderaxespad

                 # spacing & pad defined as a fraction of the font-size
                 borderpad = None,     # the whitespace inside the legend border
                 labelspacing=None, #the vertical space between the legend entries
                 handlelength=None, # the length of the legend handles
                 handletextpad=None, # the pad between the legend handle and text
                 borderaxespad=None, # the pad between the axes and legend border
                 columnspacing=None, # spacing between columns

                 ncol=1, # number of columns
                 mode=None, # mode for horizontal distribution of columns. None, "expand"

                 fancybox=None, # True use a fancy box, false use a rounded box, none use rc
                 shadow = None,
                 title = None, # set a title for the legend
                 bbox_to_anchor = None, # bbox that the legend will be anchored.
                 bbox_transform = None, # transform for the bbox
                 ):
        """
        - *parent* : the artist that contains the legend
        - *handles* : a list of artists (lines, patches) to add to the legend
        - *labels* : a list of strings to label the legend

        Optional keyword arguments:

        ================   ==================================================================
        Keyword            Description
        ================   ==================================================================
        loc                a location code
        prop               the font property
        markerscale        the relative size of legend markers vs. original
        numpoints          the number of points in the legend for line
        scatterpoints      the number of points in the legend for scatter plot
        scatteryoffsets    a list of yoffsets for scatter symbols in legend
        fancybox           if True, draw a frame with a round fancybox.  If None, use rc
        shadow             if True, draw a shadow behind legend
        ncol               number of columns
        borderpad          the fractional whitespace inside the legend border
        labelspacing       the vertical space between the legend entries
        handlelength       the length of the legend handles
        handletextpad      the pad between the legend handle and text
        borderaxespad      the pad between the axes and legend border
        columnspacing      the spacing between columns
        title              the legend title
        bbox_to_anchor     the bbox that the legend will be anchored.
        bbox_transform     the transform for the bbox. transAxes if None.
        ================   ==================================================================

The dimensions of pad and spacing are given as a fraction of the
_fontsize. Values from rcParams will be used if None.

Users can specify any arbitrary location for the legend using the
*bbox_to_anchor* keyword argument. bbox_to_anchor can be an instance
of BboxBase(or its derivatives) or a tuple of 2 or 4 floats.
See :meth:`set_bbox_to_anchor` for more detail.

The legend location can be specified by setting *loc* with a tuple of
2 floats, which is interpreted as the lower-left corner of the legend
in the normalized axes coordinate.
        """
        from matplotlib.axes import Axes     # local import only to avoid circularity
        from matplotlib.figure import Figure # local import only to avoid circularity

        Artist.__init__(self)

        if prop is None:
            self.prop=FontProperties(size=rcParams["legend.fontsize"])
        elif isinstance(prop, dict):
            self.prop=FontProperties(**prop)
            if "size" not in prop:
                self.prop.set_size(rcParams["legend.fontsize"])
        else:
            self.prop=prop

        self._fontsize = self.prop.get_size_in_points()

        propnames=['numpoints', 'markerscale', 'shadow', "columnspacing",
                   "scatterpoints"]

        localdict = locals()

        for name in propnames:
            if localdict[name] is None:
                value = rcParams["legend."+name]
            else:
                value = localdict[name]
            setattr(self, name, value)

        # Take care the deprecated keywords
        deprecated_kwds = {"pad":"borderpad",
                           "labelsep":"labelspacing",
                           "handlelen":"handlelength",
                           "handletextsep":"handletextpad",
                           "axespad":"borderaxespad"}

        # convert values of deprecated keywords (ginve in axes coords)
        # to new vaules in a fraction of the font size

        # conversion factor
        bbox = parent.bbox
        axessize_fontsize = min(bbox.width, bbox.height)/self._fontsize

        for k, v in deprecated_kwds.items():
            # use deprecated value if not None and if their newer
            # counter part is None.
            if localdict[k] is not None and localdict[v] is None:
                warnings.warn("Use '%s' instead of '%s'." % (v, k),
                              DeprecationWarning)
                setattr(self, v, localdict[k]*axessize_fontsize)
                continue

            # Otherwise, use new keywords
            if localdict[v] is None:
                setattr(self, v, rcParams["legend."+v])
            else:
                setattr(self, v, localdict[v])

        del localdict

        handles = list(handles)
        if len(handles)<2:
            ncol = 1
        self._ncol = ncol

        if self.numpoints <= 0:
            raise ValueError("numpoints must be >= 0; it was %d"% numpoints)

        # introduce y-offset for handles of the scatter plot
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3./8., 4./8., 2.5/8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps =  int(self.numpoints / len(self._scatteryoffsets)) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets, reps)[:self.scatterpoints]

        # _legend_box is an OffsetBox instance that contains all
        # legend items and will be initialized from _init_legend_box()
        # method.
        self._legend_box = None

        if isinstance(parent,Axes):
            self.isaxes = True
            self.set_figure(parent.figure)
        elif isinstance(parent,Figure):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError("Legend needs either Axes or Figure as parent")
        self.parent = parent

        if loc is None:
            loc = rcParams["legend.loc"]
            if not self.isaxes and loc in [0,'best']:
                loc = 'upper right'
        if is_string_like(loc):
            if loc not in self.codes:
                if self.isaxes:
                    warnings.warn('Unrecognized location "%s". Falling back on "best"; '
                                  'valid locations are\n\t%s\n'
                                  % (loc, '\n\t'.join(self.codes.keys())))
                    loc = 0
                else:
                    warnings.warn('Unrecognized location "%s". Falling back on "upper right"; '
                                  'valid locations are\n\t%s\n'
                                   % (loc, '\n\t'.join(self.codes.keys())))
                    loc = 1
            else:
                loc = self.codes[loc]
        if not self.isaxes and loc == 0:
            warnings.warn('Automatic legend placement (loc="best") not implemented for figure legend. '
                          'Falling back on "upper right".')
            loc = 1

        self._loc = loc
        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

        # We use FancyBboxPatch to draw a legend frame. The location
        # and size of the box will be updated during the drawing time.
        self.legendPatch = FancyBboxPatch(
            xy=(0.0, 0.0), width=1., height=1.,
            facecolor='w', edgecolor='k',
            mutation_scale=self._fontsize,
            snap=True
            )

        # The width and height of the legendPatch will be set (in the
        # draw()) to the length that includes the padding. Thus we set
        # pad=0 here.
        if fancybox is None:
            fancybox = rcParams["legend.fancybox"]

        if fancybox == True:
            self.legendPatch.set_boxstyle("round",pad=0,
                                          rounding_size=0.2)
        else:
            self.legendPatch.set_boxstyle("square",pad=0)

        self._set_artist_props(self.legendPatch)

        self._drawFrame = True

        # init with null renderer
        self._init_legend_box(handles, labels)

        self.set_title(title)

        self._last_fontsize_points = self._fontsize


    def _set_artist_props(self, a):
        """
        set the boilerplate props for artists added to axes
        """
        a.set_figure(self.figure)

        for c in self.get_children():
            c.set_figure(self.figure)

        a.set_transform(self.get_transform())


    def _findoffset_best(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend at its best position"
        ox, oy = self._find_best_position(width, height, renderer)
        return ox+xdescent, oy+ydescent

    def _findoffset_loc(self, width, height, xdescent, ydescent, renderer):
        "Heper function to locate the legend using the location code"

        if iterable(self._loc) and len(self._loc)==2:
            # when loc is a tuple of axes(or figure) coordinates.
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy
        else:
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox, self.get_bbox_to_anchor(), renderer)

        return x+xdescent, y+ydescent

    @allow_rasterization
    def draw(self, renderer):
        "Draw everything that belongs to the legend"
        if not self.get_visible(): return


        renderer.open_group('legend')


        # find_offset function will be provided to _legend_box and
        # _legend_box will draw itself at the location of the return
        # value of the find_offset.
        if self._loc == 0:
            _findoffset = self._findoffset_best
        else:
            _findoffset = self._findoffset_loc

        def findoffset(width, height, xdescent, ydescent):
            return _findoffset(width, height, xdescent, ydescent, renderer)

        self._legend_box.set_offset(findoffset)

        fontsize = renderer.points_to_pixels(self._fontsize)

        # if mode == fill, set the width of the legend_box to the
        # width of the paret (minus pads)
        if self._mode in ["expand"]:
            pad = 2*(self.borderaxespad+self.borderpad)*fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width-pad)

        if self._drawFrame:
            # update the location and size of the legend
            bbox = self._legend_box.get_window_extent(renderer)
            self.legendPatch.set_bounds(bbox.x0, bbox.y0,
                                        bbox.width, bbox.height)

            self.legendPatch.set_mutation_scale(fontsize)

            if self.shadow:
                shadow = Shadow(self.legendPatch, 2, -2)
                shadow.draw(renderer)

            self.legendPatch.draw(renderer)

        self._legend_box.draw(renderer)

        renderer.close_group('legend')


    def _approx_text_height(self, renderer=None):
        """
        Return the approximate height of the text. This is used to place
        the legend handle.
        """
        if renderer is None:
            return self._fontsize
        else:
            return renderer.points_to_pixels(self._fontsize)


    def _init_legend_box(self, handles, labels):
        """
        Initiallize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """

        fontsize = self._fontsize

        # legend_box is a HPacker, horizontally packed with
        # columns. Each column is a VPacker, vertically packed with
        # legend items. Each legend item is HPacker packed with
        # legend handleBox and labelBox. handleBox is an instance of
        # offsetbox.DrawingArea which contains legend handle. labelBox
        # is an instance of offsetbox.TextArea which contains legend
        # text.


        text_list = []  # the list of text instances
        handle_list = []  # the list of text instances

        label_prop = dict(verticalalignment='baseline',
                          horizontalalignment='left',
                          fontproperties=self.prop,
                          )

        labelboxes = []

        for l in labels:
            textbox = TextArea(l, textprops=label_prop,
                               multilinebaseline=True, minimumdescent=True)
            text_list.append(textbox._text)
            labelboxes.append(textbox)

        handleboxes = []


        # The approximate height and descent of text. These values are
        # only used for plotting the legend handle.
        height = self._approx_text_height() * 0.7
        descent = 0.

        # each handle needs to be drawn inside a box of (x, y, w, h) =
        # (0, -descent, width, height).  And their corrdinates should
        # be given in the display coordinates.

        # The transformation of each handle will be automatically set
        # to self.get_trasnform(). If the artist does not uses its
        # default trasnform (eg, Collections), you need to
        # manually set their transform to the self.get_transform().

        for handle in handles:
            if isinstance(handle, RegularPolyCollection) or \
                   isinstance(handle, CircleCollection):
                npoints = self.scatterpoints
            else:
                npoints = self.numpoints
            if npoints > 1:
                # we put some pad here to compensate the size of the
                # marker
                xdata = np.linspace(0.3*fontsize,
                                    (self.handlelength-0.3)*fontsize,
                                    npoints)
                xdata_marker = xdata
            elif npoints == 1:
                xdata = np.linspace(0, self.handlelength*fontsize, 2)
                xdata_marker = [0.5*self.handlelength*fontsize]

            if isinstance(handle, Line2D):
                ydata = ((height-descent)/2.)*np.ones(xdata.shape, float)
                legline = Line2D(xdata, ydata)

                legline.update_from(handle)
                self._set_artist_props(legline) # after update
                legline.set_clip_box(None)
                legline.set_clip_path(None)
                legline.set_drawstyle('default')
                legline.set_marker('None')

                handle_list.append(legline)

                legline_marker = Line2D(xdata_marker, ydata[:len(xdata_marker)])
                legline_marker.update_from(handle)
                self._set_artist_props(legline_marker)
                legline_marker.set_clip_box(None)
                legline_marker.set_clip_path(None)
                legline_marker.set_linestyle('None')
                # we don't want to add this to the return list because
                # the texts and handles are assumed to be in one-to-one
                # correpondence.
                legline._legmarker = legline_marker

            elif isinstance(handle, Patch):
                p = Rectangle(xy=(0., 0.),
                              width = self.handlelength*fontsize,
                              height=(height-descent),
                              )
                p.update_from(handle)
                self._set_artist_props(p)
                p.set_clip_box(None)
                p.set_clip_path(None)
                handle_list.append(p)
            elif isinstance(handle, LineCollection):
                ydata = ((height-descent)/2.)*np.ones(xdata.shape, float)
                legline = Line2D(xdata, ydata)
                self._set_artist_props(legline)
                legline.set_clip_box(None)
                legline.set_clip_path(None)
                lw = handle.get_linewidth()[0]
                dashes = handle.get_dashes()[0]
                color = handle.get_colors()[0]
                legline.set_color(color)
                legline.set_linewidth(lw)
                if dashes[0] is not None: # dashed line
                    legline.set_dashes(dashes[1])
                handle_list.append(legline)

            elif isinstance(handle, RegularPolyCollection):

                #ydata = self._scatteryoffsets
                ydata = height*self._scatteryoffsets

                size_max, size_min = max(handle.get_sizes()),\
                                     min(handle.get_sizes())
                # we may need to scale these sizes by "markerscale"
                # attribute. But other handle types does not seem
                # to care about this attribute and it is currently ignored.
                if self.scatterpoints < 4:
                    sizes = [.5*(size_max+size_min), size_max,
                             size_min]
                else:
                    sizes = (size_max-size_min)*np.linspace(0,1,self.scatterpoints)+size_min

                p = type(handle)(handle.get_numsides(),
                                 rotation=handle.get_rotation(),
                                 sizes=sizes,
                                 offsets=zip(xdata_marker,ydata),
                                 transOffset=self.get_transform(),
                                 )

                p.update_from(handle)
                p.set_figure(self.figure)
                p.set_clip_box(None)
                p.set_clip_path(None)
                handle_list.append(p)

            elif isinstance(handle, CircleCollection):

                ydata = height*self._scatteryoffsets

                size_max, size_min = max(handle.get_sizes()),\
                                     min(handle.get_sizes())
                # we may need to scale these sizes by "markerscale"
                # attribute. But other handle types does not seem
                # to care about this attribute and it is currently ignored.
                if self.scatterpoints < 4:
                    sizes = [.5*(size_max+size_min), size_max,
                             size_min]
                else:
                    sizes = (size_max-size_min)*np.linspace(0,1,self.scatterpoints)+size_min

                p = type(handle)(sizes,
                                 offsets=zip(xdata_marker,ydata),
                                 transOffset=self.get_transform(),
                                 )

                p.update_from(handle)
                p.set_figure(self.figure)
                p.set_clip_box(None)
                p.set_clip_path(None)
                handle_list.append(p)
            else:
                handle_list.append(None)

            handlebox = DrawingArea(width=self.handlelength*fontsize,
                                    height=height,
                                    xdescent=0., ydescent=descent)

            handle = handle_list[-1]
            handlebox.add_artist(handle)
            if hasattr(handle, "_legmarker"):
                handlebox.add_artist(handle._legmarker)
            handleboxes.append(handlebox)


        # We calculate number of lows in each column. The first
        # (num_largecol) columns will have (nrows+1) rows, and remaing
        # (num_smallcol) columns will have (nrows) rows.
        ncol = min(self._ncol, len(handleboxes))
        nrows, num_largecol = divmod(len(handleboxes), ncol)
        num_smallcol = ncol-num_largecol

        # starting index of each column and number of rows in it.
        largecol = safezip(range(0, num_largecol*(nrows+1), (nrows+1)),
                           [nrows+1] * num_largecol)
        smallcol = safezip(range(num_largecol*(nrows+1), len(handleboxes), nrows),
                           [nrows] * num_smallcol)

        handle_label = safezip(handleboxes, labelboxes)
        columnbox = []
        for i0, di in largecol+smallcol:
            # pack handleBox and labelBox into itemBox
            itemBoxes = [HPacker(pad=0,
                                 sep=self.handletextpad*fontsize,
                                 children=[h, t], align="baseline")
                         for h, t in handle_label[i0:i0+di]]
            # minimumdescent=False for the text of the last row of the column
            itemBoxes[-1].get_children()[1].set_minimumdescent(False)

            # pack columnBox
            columnbox.append(VPacker(pad=0,
                                        sep=self.labelspacing*fontsize,
                                        align="baseline",
                                        children=itemBoxes))

        if self._mode == "expand":
            mode = "expand"
        else:
            mode = "fixed"

        sep = self.columnspacing*fontsize

        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep, align="baseline",
                                          mode=mode,
                                          children=columnbox)

        self._legend_title_box = TextArea("")

        self._legend_box = VPacker(pad=self.borderpad*fontsize,
                                   sep=self.labelspacing*fontsize,
                                   align="center",
                                   children=[self._legend_title_box,
                                             self._legend_handle_box])

        self._legend_box.set_figure(self.figure)

        self.texts = text_list
        self.legendHandles = handle_list


    def _auto_legend_data(self):
        """
        Returns list of vertices and extents covered by the plot.

        Returns a two long list.

        First element is a list of (x, y) vertices (in
        display-coordinates) covered by all the lines and line
        collections, in the legend's handles.

        Second element is a list of bounding boxes for all the patches in
        the legend's handles.
        """

        assert self.isaxes # should always hold because function is only called internally

        ax = self.parent
        vertices = []
        bboxes = []
        lines = []

        for handle in ax.lines:
            assert isinstance(handle, Line2D)
            path = handle.get_path()
            trans = handle.get_transform()
            tpath = trans.transform_path(path)
            lines.append(tpath)

        for handle in ax.patches:
            assert isinstance(handle, Patch)

            if isinstance(handle, Rectangle):
                transform = handle.get_data_transform()
                bboxes.append(handle.get_bbox().transformed(transform))
            else:
                transform = handle.get_transform()
                bboxes.append(handle.get_path().get_extents(transform))

        return [vertices, bboxes, lines]

    def draw_frame(self, b):
        'b is a boolean.  Set draw frame to b'
        self._drawFrame = b

    def get_children(self):
        'return a list of child artists'
        children = []
        if self._legend_box:
            children.append(self._legend_box)
        return children

    def get_frame(self):
        'return the Rectangle instance used to frame the legend'
        return self.legendPatch

    def get_lines(self):
        'return a list of lines.Line2D instances in the legend'
        return [h for h in self.legendHandles if isinstance(h, Line2D)]

    def get_patches(self):
        'return a list of patch instances in the legend'
        return silent_list('Patch', [h for h in self.legendHandles if isinstance(h, Patch)])

    def get_texts(self):
        'return a list of text.Text instance in the legend'
        return silent_list('Text', self.texts)

    def set_title(self, title):
        'set the legend title'
        self._legend_title_box._text.set_text(title)

        if title:
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box.set_visible(False)

    def get_title(self):
        'return Text instance for the legend title'
        return self._legend_title_box._text

    def get_window_extent(self):
        'return a extent of the the legend'
        return self.legendPatch.get_window_extent()


    def get_bbox_to_anchor(self):
        """
        return the bbox that the legend will be anchored
        """
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor


    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        set the bbox that the legend will be anchored.

        *bbox* can be a BboxBase instance, a tuple of [left, bottom,
        width, height] in the given transform (normalized axes
        coordinate if None), or a tuple of [left, bottom] where the
        width and height will be assumed to be zero.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError:
                raise ValueError("Invalid argument for bbox : %s" % str(bbox))

            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]

            self._bbox_to_anchor = Bbox.from_bounds(*bbox)

        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)

        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor,
                                               transform)



    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x,y) coordinate of the bbox.

        - loc: a location code in range(1, 11).
          This corresponds to the possible values for self._loc, excluding "best".

        - bbox: bbox to be placed, display coodinate units.
        - parentbbox: a parent box which will contain the bbox. In
            display coordinates.
        """
        assert loc in range(1,11) # called only internally

        BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = range(11)

        anchor_coefs={UR:"NE",
                      UL:"NW",
                      LL:"SW",
                      LR:"SE",
                      R:"E",
                      CL:"W",
                      CR:"E",
                      LC:"S",
                      UC:"N",
                      C:"C"}

        c = anchor_coefs[loc]

        fontsize = renderer.points_to_pixels(self._fontsize)
        container = parentbbox.padded(-(self.borderaxespad) * fontsize)
        anchored_box = bbox.anchored(c, container=container)
        return anchored_box.x0, anchored_box.y0


    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.

        `consider` is a list of (x, y) pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """

        assert self.isaxes # should always hold because function is only called internally

        verts, bboxes, lines = self._auto_legend_data()

        bbox = Bbox.from_bounds(0, 0, width, height)
        consider = [self._get_anchored_bbox(x, bbox, self.get_bbox_to_anchor(),
                                            renderer) for x in range(1, len(self.codes))]

        #tx, ty = self.legendPatch.get_x(), self.legendPatch.get_y()

        candidates = []
        for l, b in consider:
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            badness = legendBox.count_contains(verts)
            badness += legendBox.count_overlaps(bboxes)
            for line in lines:
                if line.intersects_bbox(legendBox):
                    badness += 1

            ox, oy = l, b
            if badness == 0:
                return ox, oy

            candidates.append((badness, (l, b)))

        # rather than use min() or list.sort(), do this so that we are assured
        # that in the case of two equal badnesses, the one first considered is
        # returned.
        # NOTE: list.sort() is stable.But leave as it is for now. -JJL
        minCandidate = candidates[0]
        for candidate in candidates:
            if candidate[0] < minCandidate[0]:
                minCandidate = candidate

        ox, oy = minCandidate[1]

        return ox, oy
Exemple #8
0
class Legend(Artist):
    """
    Place a legend on the axes at location loc.

    """
    codes = {'best':         0,  # only implemented for axes legends
             'upper right':  1,
             'upper left':   2,
             'lower left':   3,
             'lower right':  4,
             'right':        5,
             'center left':  6,
             'center right': 7,
             'lower center': 8,
             'upper center': 9,
             'center':       10,
             }

    zorder = 5

    def __str__(self):
        return "Legend"

    @docstring.dedent_interpd
    def __init__(self, parent, handles, labels,
                 loc=None,
                 numpoints=None,    # the number of points in the legend line
                 markerscale=None,  # the relative size of legend markers
                                    # vs. original
                 markerfirst=True,  # controls ordering (left-to-right) of
                                    # legend marker and label
                 scatterpoints=None,    # number of scatter points
                 scatteryoffsets=None,
                 prop=None,          # properties for the legend texts
                 fontsize=None,        # keyword to set font size directly

                 # spacing & pad defined as a fraction of the font-size
                 borderpad=None,      # the whitespace inside the legend border
                 labelspacing=None,   # the vertical space between the legend
                                      # entries
                 handlelength=None,   # the length of the legend handles
                 handleheight=None,   # the height of the legend handles
                 handletextpad=None,  # the pad between the legend handle
                                      # and text
                 borderaxespad=None,  # the pad between the axes and legend
                                      # border
                 columnspacing=None,  # spacing between columns

                 ncol=1,     # number of columns
                 mode=None,  # mode for horizontal distribution of columns.
                             # None, "expand"

                 fancybox=None,  # True use a fancy box, false use a rounded
                                 # box, none use rc
                 shadow=None,
                 title=None,  # set a title for the legend
                 title_fontsize=None,  # set to ax.fontsize if None
                 framealpha=None,  # set frame alpha
                 edgecolor=None,  # frame patch edgecolor
                 facecolor=None,  # frame patch facecolor

                 bbox_to_anchor=None,  # bbox that the legend will be anchored.
                 bbox_transform=None,  # transform for the bbox
                 frameon=None,  # draw frame
                 handler_map=None,
                 ):
        """
        Parameters
        ----------
        parent : `~matplotlib.axes.Axes` or `.Figure`
            The artist that contains the legend.

        handles : sequence of `.Artist`
            A list of Artists (lines, patches) to be added to the legend.

        labels : sequence of strings
            A list of labels to show next to the artists. The length of handles
            and labels should be the same. If they are not, they are truncated
            to the smaller of both lengths.

        Other Parameters
        ----------------

        %(_legend_kw_doc)s

        Notes
        -----

        Users can specify any arbitrary location for the legend using the
        *bbox_to_anchor* keyword argument. bbox_to_anchor can be an instance
        of BboxBase(or its derivatives) or a tuple of 2 or 4 floats.
        See :meth:`set_bbox_to_anchor` for more detail.

        The legend location can be specified by setting *loc* with a tuple of
        2 floats, which is interpreted as the lower-left corner of the legend
        in the normalized axes coordinate.
        """
        # local import only to avoid circularity
        from matplotlib.axes import Axes
        from matplotlib.figure import Figure

        Artist.__init__(self)

        if prop is None:
            if fontsize is not None:
                self.prop = FontProperties(size=fontsize)
            else:
                self.prop = FontProperties(size=rcParams["legend.fontsize"])
        elif isinstance(prop, dict):
            self.prop = FontProperties(**prop)
            if "size" not in prop:
                self.prop.set_size(rcParams["legend.fontsize"])
        else:
            self.prop = prop

        self._fontsize = self.prop.get_size_in_points()

        self.texts = []
        self.legendHandles = []
        self._legend_title_box = None

        #: A dictionary with the extra handler mappings for this Legend
        #: instance.
        self._custom_handler_map = handler_map

        locals_view = locals()
        for name in ["numpoints", "markerscale", "shadow", "columnspacing",
                     "scatterpoints", "handleheight", 'borderpad',
                     'labelspacing', 'handlelength', 'handletextpad',
                     'borderaxespad']:
            if locals_view[name] is None:
                value = rcParams["legend." + name]
            else:
                value = locals_view[name]
            setattr(self, name, value)
        del locals_view
        # trim handles and labels if illegal label...
        _lab, _hand = [], []
        for label, handle in zip(labels, handles):
            if isinstance(label, str) and label.startswith('_'):
                cbook._warn_external('The handle {!r} has a label of {!r} '
                                     'which cannot be automatically added to'
                                     ' the legend.'.format(handle, label))
            else:
                _lab.append(label)
                _hand.append(handle)
        labels, handles = _lab, _hand

        handles = list(handles)
        if len(handles) < 2:
            ncol = 1
        self._ncol = ncol

        if self.numpoints <= 0:
            raise ValueError("numpoints must be > 0; it was %d" % numpoints)

        # introduce y-offset for handles of the scatter plot
        if scatteryoffsets is None:
            self._scatteryoffsets = np.array([3. / 8., 4. / 8., 2.5 / 8.])
        else:
            self._scatteryoffsets = np.asarray(scatteryoffsets)
        reps = self.scatterpoints // len(self._scatteryoffsets) + 1
        self._scatteryoffsets = np.tile(self._scatteryoffsets,
                                        reps)[:self.scatterpoints]

        # _legend_box is an OffsetBox instance that contains all
        # legend items and will be initialized from _init_legend_box()
        # method.
        self._legend_box = None

        if isinstance(parent, Axes):
            self.isaxes = True
            self.axes = parent
            self.set_figure(parent.figure)
        elif isinstance(parent, Figure):
            self.isaxes = False
            self.set_figure(parent)
        else:
            raise TypeError("Legend needs either Axes or Figure as parent")
        self.parent = parent

        self._loc_used_default = loc is None
        if loc is None:
            loc = rcParams["legend.loc"]
            if not self.isaxes and loc in [0, 'best']:
                loc = 'upper right'
        if isinstance(loc, str):
            if loc not in self.codes:
                if self.isaxes:
                    cbook.warn_deprecated(
                        "3.1", message="Unrecognized location {!r}. Falling "
                        "back on 'best'; valid locations are\n\t{}\n"
                        "This will raise an exception %(removal)s."
                        .format(loc, '\n\t'.join(self.codes)))
                    loc = 0
                else:
                    cbook.warn_deprecated(
                        "3.1", message="Unrecognized location {!r}. Falling "
                        "back on 'upper right'; valid locations are\n\t{}\n'"
                        "This will raise an exception %(removal)s."
                        .format(loc, '\n\t'.join(self.codes)))
                    loc = 1
            else:
                loc = self.codes[loc]
        if not self.isaxes and loc == 0:
            cbook.warn_deprecated(
                "3.1", message="Automatic legend placement (loc='best') not "
                "implemented for figure legend. Falling back on 'upper "
                "right'. This will raise an exception %(removal)s.")
            loc = 1

        self._mode = mode
        self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

        # We use FancyBboxPatch to draw a legend frame. The location
        # and size of the box will be updated during the drawing time.

        if facecolor is None:
            facecolor = rcParams["legend.facecolor"]
        if facecolor == 'inherit':
            facecolor = rcParams["axes.facecolor"]

        if edgecolor is None:
            edgecolor = rcParams["legend.edgecolor"]
        if edgecolor == 'inherit':
            edgecolor = rcParams["axes.edgecolor"]

        self.legendPatch = FancyBboxPatch(
            xy=(0.0, 0.0), width=1., height=1.,
            facecolor=facecolor,
            edgecolor=edgecolor,
            mutation_scale=self._fontsize,
            snap=True
            )

        # The width and height of the legendPatch will be set (in the
        # draw()) to the length that includes the padding. Thus we set
        # pad=0 here.
        if fancybox is None:
            fancybox = rcParams["legend.fancybox"]

        if fancybox:
            self.legendPatch.set_boxstyle("round", pad=0,
                                          rounding_size=0.2)
        else:
            self.legendPatch.set_boxstyle("square", pad=0)

        self._set_artist_props(self.legendPatch)

        self._drawFrame = frameon
        if frameon is None:
            self._drawFrame = rcParams["legend.frameon"]

        # init with null renderer
        self._init_legend_box(handles, labels, markerfirst)

        # If shadow is activated use framealpha if not
        # explicitly passed. See Issue 8943
        if framealpha is None:
            if shadow:
                self.get_frame().set_alpha(1)
            else:
                self.get_frame().set_alpha(rcParams["legend.framealpha"])
        else:
            self.get_frame().set_alpha(framealpha)

        tmp = self._loc_used_default
        self._set_loc(loc)
        self._loc_used_default = tmp  # ignore changes done by _set_loc

        # figure out title fontsize:
        if title_fontsize is None:
            title_fontsize = rcParams['legend.title_fontsize']
        tprop = FontProperties(size=title_fontsize)
        self.set_title(title, prop=tprop)
        self._last_fontsize_points = self._fontsize
        self._draggable = None

    def _set_artist_props(self, a):
        """
        Set the boilerplate props for artists added to axes.
        """
        a.set_figure(self.figure)
        if self.isaxes:
            # a.set_axes(self.axes)
            a.axes = self.axes

        a.set_transform(self.get_transform())

    def _set_loc(self, loc):
        # find_offset function will be provided to _legend_box and
        # _legend_box will draw itself at the location of the return
        # value of the find_offset.
        self._loc_used_default = False
        self._loc_real = loc
        self.stale = True
        self._legend_box.set_offset(self._findoffset)

    def _get_loc(self):
        return self._loc_real

    _loc = property(_get_loc, _set_loc)

    def _findoffset(self, width, height, xdescent, ydescent, renderer):
        "Helper function to locate the legend."

        if self._loc == 0:  # "best".
            x, y = self._find_best_position(width, height, renderer)
        elif self._loc in Legend.codes.values():  # Fixed location.
            bbox = Bbox.from_bounds(0, 0, width, height)
            x, y = self._get_anchored_bbox(self._loc, bbox,
                                           self.get_bbox_to_anchor(),
                                           renderer)
        else:  # Axes or figure coordinates.
            fx, fy = self._loc
            bbox = self.get_bbox_to_anchor()
            x, y = bbox.x0 + bbox.width * fx, bbox.y0 + bbox.height * fy

        return x + xdescent, y + ydescent

    @allow_rasterization
    def draw(self, renderer):
        "Draw everything that belongs to the legend."
        if not self.get_visible():
            return

        renderer.open_group('legend')

        fontsize = renderer.points_to_pixels(self._fontsize)

        # if mode == fill, set the width of the legend_box to the
        # width of the parent (minus pads)
        if self._mode in ["expand"]:
            pad = 2 * (self.borderaxespad + self.borderpad) * fontsize
            self._legend_box.set_width(self.get_bbox_to_anchor().width - pad)

        # update the location and size of the legend. This needs to
        # be done in any case to clip the figure right.
        bbox = self._legend_box.get_window_extent(renderer)
        self.legendPatch.set_bounds(bbox.x0, bbox.y0,
                                    bbox.width, bbox.height)
        self.legendPatch.set_mutation_scale(fontsize)

        if self._drawFrame:
            if self.shadow:
                shadow = Shadow(self.legendPatch, 2, -2)
                shadow.draw(renderer)

            self.legendPatch.draw(renderer)

        self._legend_box.draw(renderer)

        renderer.close_group('legend')
        self.stale = False

    def _approx_text_height(self, renderer=None):
        """
        Return the approximate height of the text. This is used to place
        the legend handle.
        """
        if renderer is None:
            return self._fontsize
        else:
            return renderer.points_to_pixels(self._fontsize)

    # _default_handler_map defines the default mapping between plot
    # elements and the legend handlers.

    _default_handler_map = {
        StemContainer: legend_handler.HandlerStem(),
        ErrorbarContainer: legend_handler.HandlerErrorbar(),
        Line2D: legend_handler.HandlerLine2D(),
        Patch: legend_handler.HandlerPatch(),
        LineCollection: legend_handler.HandlerLineCollection(),
        RegularPolyCollection: legend_handler.HandlerRegularPolyCollection(),
        CircleCollection: legend_handler.HandlerCircleCollection(),
        BarContainer: legend_handler.HandlerPatch(
            update_func=legend_handler.update_from_first_child),
        tuple: legend_handler.HandlerTuple(),
        PathCollection: legend_handler.HandlerPathCollection(),
        PolyCollection: legend_handler.HandlerPolyCollection()
        }

    # (get|set|update)_default_handler_maps are public interfaces to
    # modify the default handler map.

    @classmethod
    def get_default_handler_map(cls):
        """
        A class method that returns the default handler map.
        """
        return cls._default_handler_map

    @classmethod
    def set_default_handler_map(cls, handler_map):
        """
        A class method to set the default handler map.
        """
        cls._default_handler_map = handler_map

    @classmethod
    def update_default_handler_map(cls, handler_map):
        """
        A class method to update the default handler map.
        """
        cls._default_handler_map.update(handler_map)

    def get_legend_handler_map(self):
        """
        Return the handler map.
        """

        default_handler_map = self.get_default_handler_map()

        if self._custom_handler_map:
            hm = default_handler_map.copy()
            hm.update(self._custom_handler_map)
            return hm
        else:
            return default_handler_map

    @staticmethod
    def get_legend_handler(legend_handler_map, orig_handle):
        """
        Return a legend handler from *legend_handler_map* that
        corresponds to *orig_handler*.

        *legend_handler_map* should be a dictionary object (that is
        returned by the get_legend_handler_map method).

        It first checks if the *orig_handle* itself is a key in the
        *legend_handler_map* and return the associated value.
        Otherwise, it checks for each of the classes in its
        method-resolution-order. If no matching key is found, it
        returns ``None``.
        """
        if is_hashable(orig_handle):
            try:
                return legend_handler_map[orig_handle]
            except KeyError:
                pass

        for handle_type in type(orig_handle).mro():
            try:
                return legend_handler_map[handle_type]
            except KeyError:
                pass

        return None

    def _init_legend_box(self, handles, labels, markerfirst=True):
        """
        Initialize the legend_box. The legend_box is an instance of
        the OffsetBox, which is packed with legend handles and
        texts. Once packed, their location is calculated during the
        drawing time.
        """

        fontsize = self._fontsize

        # legend_box is a HPacker, horizontally packed with
        # columns. Each column is a VPacker, vertically packed with
        # legend items. Each legend item is HPacker packed with
        # legend handleBox and labelBox. handleBox is an instance of
        # offsetbox.DrawingArea which contains legend handle. labelBox
        # is an instance of offsetbox.TextArea which contains legend
        # text.

        text_list = []  # the list of text instances
        handle_list = []  # the list of text instances
        handles_and_labels = []

        label_prop = dict(verticalalignment='baseline',
                          horizontalalignment='left',
                          fontproperties=self.prop,
                          )

        # The approximate height and descent of text. These values are
        # only used for plotting the legend handle.
        descent = 0.35 * self._approx_text_height() * (self.handleheight - 0.7)
        # 0.35 and 0.7 are just heuristic numbers and may need to be improved.
        height = self._approx_text_height() * self.handleheight - descent
        # each handle needs to be drawn inside a box of (x, y, w, h) =
        # (0, -descent, width, height).  And their coordinates should
        # be given in the display coordinates.

        # The transformation of each handle will be automatically set
        # to self.get_transform(). If the artist does not use its
        # default transform (e.g., Collections), you need to
        # manually set their transform to the self.get_transform().
        legend_handler_map = self.get_legend_handler_map()

        for orig_handle, lab in zip(handles, labels):
            handler = self.get_legend_handler(legend_handler_map, orig_handle)
            if handler is None:
                cbook._warn_external(
                    "Legend does not support {!r} instances.\nA proxy artist "
                    "may be used instead.\nSee: "
                    "http://matplotlib.org/users/legend_guide.html"
                    "#creating-artists-specifically-for-adding-to-the-legend-"
                    "aka-proxy-artists".format(orig_handle))
                # We don't have a handle for this artist, so we just defer
                # to None.
                handle_list.append(None)
            else:
                textbox = TextArea(lab, textprops=label_prop,
                                   multilinebaseline=True,
                                   minimumdescent=True)
                handlebox = DrawingArea(width=self.handlelength * fontsize,
                                        height=height,
                                        xdescent=0., ydescent=descent)

                text_list.append(textbox._text)
                # Create the artist for the legend which represents the
                # original artist/handle.
                handle_list.append(handler.legend_artist(self, orig_handle,
                                                         fontsize, handlebox))
                handles_and_labels.append((handlebox, textbox))

        if handles_and_labels:
            # We calculate number of rows in each column. The first
            # (num_largecol) columns will have (nrows+1) rows, and remaining
            # (num_smallcol) columns will have (nrows) rows.
            ncol = min(self._ncol, len(handles_and_labels))
            nrows, num_largecol = divmod(len(handles_and_labels), ncol)
            num_smallcol = ncol - num_largecol
            # starting index of each column and number of rows in it.
            rows_per_col = [nrows + 1] * num_largecol + [nrows] * num_smallcol
            start_idxs = np.concatenate([[0], np.cumsum(rows_per_col)[:-1]])
            cols = zip(start_idxs, rows_per_col)
        else:
            cols = []

        columnbox = []
        for i0, di in cols:
            # pack handleBox and labelBox into itemBox
            itemBoxes = [HPacker(pad=0,
                                 sep=self.handletextpad * fontsize,
                                 children=[h, t] if markerfirst else [t, h],
                                 align="baseline")
                         for h, t in handles_and_labels[i0:i0 + di]]
            # minimumdescent=False for the text of the last row of the column
            if markerfirst:
                itemBoxes[-1].get_children()[1].set_minimumdescent(False)
            else:
                itemBoxes[-1].get_children()[0].set_minimumdescent(False)

            # pack columnBox
            alignment = "baseline" if markerfirst else "right"
            columnbox.append(VPacker(pad=0,
                                     sep=self.labelspacing * fontsize,
                                     align=alignment,
                                     children=itemBoxes))

        mode = "expand" if self._mode == "expand" else "fixed"
        sep = self.columnspacing * fontsize
        self._legend_handle_box = HPacker(pad=0,
                                          sep=sep, align="baseline",
                                          mode=mode,
                                          children=columnbox)
        self._legend_title_box = TextArea("")
        self._legend_box = VPacker(pad=self.borderpad * fontsize,
                                   sep=self.labelspacing * fontsize,
                                   align="center",
                                   children=[self._legend_title_box,
                                             self._legend_handle_box])
        self._legend_box.set_figure(self.figure)
        self.texts = text_list
        self.legendHandles = handle_list

    def _auto_legend_data(self):
        """
        Returns list of vertices and extents covered by the plot.

        Returns a two long list.

        First element is a list of (x, y) vertices (in
        display-coordinates) covered by all the lines and line
        collections, in the legend's handles.

        Second element is a list of bounding boxes for all the patches in
        the legend's handles.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        ax = self.parent
        bboxes = []
        lines = []
        offsets = []

        for handle in ax.lines:
            assert isinstance(handle, Line2D)
            path = handle.get_path()
            trans = handle.get_transform()
            tpath = trans.transform_path(path)
            lines.append(tpath)

        for handle in ax.patches:
            assert isinstance(handle, Patch)

            if isinstance(handle, Rectangle):
                transform = handle.get_data_transform()
                bboxes.append(handle.get_bbox().transformed(transform))
            else:
                transform = handle.get_transform()
                bboxes.append(handle.get_path().get_extents(transform))

        for handle in ax.collections:
            transform, transOffset, hoffsets, paths = handle._prepare_points()

            if len(hoffsets):
                for offset in transOffset.transform(hoffsets):
                    offsets.append(offset)

        try:
            vertices = np.concatenate([l.vertices for l in lines])
        except ValueError:
            vertices = np.array([])

        return [vertices, bboxes, lines, offsets]

    def draw_frame(self, b):
        '''
        Set draw frame to b.

        Parameters
        ----------
        b : bool
        '''
        self.set_frame_on(b)

    def get_children(self):
        'Return a list of child artists.'
        children = []
        if self._legend_box:
            children.append(self._legend_box)
        children.append(self.get_frame())

        return children

    def get_frame(self):
        '''
        Return the `~.patches.Rectangle` instances used to frame the legend.
        '''
        return self.legendPatch

    def get_lines(self):
        'Return a list of `~.lines.Line2D` instances in the legend.'
        return [h for h in self.legendHandles if isinstance(h, Line2D)]

    def get_patches(self):
        'Return a list of `~.patches.Patch` instances in the legend.'
        return silent_list('Patch',
                           [h for h in self.legendHandles
                            if isinstance(h, Patch)])

    def get_texts(self):
        'Return a list of `~.text.Text` instances in the legend.'
        return silent_list('Text', self.texts)

    def set_title(self, title, prop=None):
        """
        Set the legend title. Fontproperties can be optionally set
        with *prop* parameter.
        """
        self._legend_title_box._text.set_text(title)
        if title:
            self._legend_title_box._text.set_visible(True)
            self._legend_title_box.set_visible(True)
        else:
            self._legend_title_box._text.set_visible(False)
            self._legend_title_box.set_visible(False)

        if prop is not None:
            if isinstance(prop, dict):
                prop = FontProperties(**prop)
            self._legend_title_box._text.set_fontproperties(prop)

        self.stale = True

    def get_title(self):
        'Return the `.Text` instance for the legend title.'
        return self._legend_title_box._text

    def get_window_extent(self, renderer=None):
        'Return extent of the legend.'
        if renderer is None:
            renderer = self.figure._cachedRenderer
        return self._legend_box.get_window_extent(renderer=renderer)

    def get_tightbbox(self, renderer):
        """
        Like `.Legend.get_window_extent`, but uses the box for the legend.

        Parameters
        ----------
        renderer : `.RendererBase` instance
            renderer that will be used to draw the figures (i.e.
            ``fig.canvas.get_renderer()``)

        Returns
        -------
        `.BboxBase` : containing the bounding box in figure pixel co-ordinates.
        """
        return self._legend_box.get_window_extent(renderer)

    def get_frame_on(self):
        """Get whether the legend box patch is drawn."""
        return self._drawFrame

    def set_frame_on(self, b):
        """
        Set whether the legend box patch is drawn.

        Parameters
        ----------
        b : bool
        """
        self._drawFrame = b
        self.stale = True

    def get_bbox_to_anchor(self):
        """Return the bbox that the legend will be anchored to."""
        if self._bbox_to_anchor is None:
            return self.parent.bbox
        else:
            return self._bbox_to_anchor

    def set_bbox_to_anchor(self, bbox, transform=None):
        """
        Set the bbox that the legend will be anchored to.

        *bbox* can be

        - A `.BboxBase` instance
        - A tuple of ``(left, bottom, width, height)`` in the given transform
          (normalized axes coordinate if None)
        - A tuple of ``(left, bottom)`` where the width and height will be
          assumed to be zero.
        """
        if bbox is None:
            self._bbox_to_anchor = None
            return
        elif isinstance(bbox, BboxBase):
            self._bbox_to_anchor = bbox
        else:
            try:
                l = len(bbox)
            except TypeError:
                raise ValueError("Invalid argument for bbox : %s" % str(bbox))

            if l == 2:
                bbox = [bbox[0], bbox[1], 0, 0]

            self._bbox_to_anchor = Bbox.from_bounds(*bbox)

        if transform is None:
            transform = BboxTransformTo(self.parent.bbox)

        self._bbox_to_anchor = TransformedBbox(self._bbox_to_anchor,
                                               transform)
        self.stale = True

    def _get_anchored_bbox(self, loc, bbox, parentbbox, renderer):
        """
        Place the *bbox* inside the *parentbbox* according to a given
        location code. Return the (x,y) coordinate of the bbox.

        - loc: a location code in range(1, 11).
          This corresponds to the possible values for self._loc, excluding
          "best".

        - bbox: bbox to be placed, display coordinate units.
        - parentbbox: a parent box which will contain the bbox. In
            display coordinates.
        """
        assert loc in range(1, 11)  # called only internally

        BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = range(11)

        anchor_coefs = {UR: "NE",
                        UL: "NW",
                        LL: "SW",
                        LR: "SE",
                        R: "E",
                        CL: "W",
                        CR: "E",
                        LC: "S",
                        UC: "N",
                        C: "C"}

        c = anchor_coefs[loc]

        fontsize = renderer.points_to_pixels(self._fontsize)
        container = parentbbox.padded(-(self.borderaxespad) * fontsize)
        anchored_box = bbox.anchored(c, container=container)
        return anchored_box.x0, anchored_box.y0

    def _find_best_position(self, width, height, renderer, consider=None):
        """
        Determine the best location to place the legend.

        *consider* is a list of ``(x, y)`` pairs to consider as a potential
        lower-left corner of the legend. All are display coords.
        """
        # should always hold because function is only called internally
        assert self.isaxes

        verts, bboxes, lines, offsets = self._auto_legend_data()
        if self._loc_used_default and verts.shape[0] > 200000:
            # this size results in a 3+ second render time on a good machine
            cbook._warn_external(
                'Creating legend with loc="best" can be slow with large '
                'amounts of data.'
            )

        bbox = Bbox.from_bounds(0, 0, width, height)
        if consider is None:
            consider = [self._get_anchored_bbox(x, bbox,
                                                self.get_bbox_to_anchor(),
                                                renderer)
                        for x in range(1, len(self.codes))]

        candidates = []
        for idx, (l, b) in enumerate(consider):
            legendBox = Bbox.from_bounds(l, b, width, height)
            badness = 0
            # XXX TODO: If markers are present, it would be good to
            # take them into account when checking vertex overlaps in
            # the next line.
            badness = (legendBox.count_contains(verts)
                       + legendBox.count_contains(offsets)
                       + legendBox.count_overlaps(bboxes)
                       + sum(line.intersects_bbox(legendBox, filled=False)
                             for line in lines))
            if badness == 0:
                return l, b
            # Include the index to favor lower codes in case of a tie.
            candidates.append((badness, idx, (l, b)))

        _, _, (l, b) = min(candidates)
        return l, b

    def contains(self, event):
        return self.legendPatch.contains(event)

    def set_draggable(self, state, use_blit=False, update='loc'):
        """
        Enable or disable mouse dragging support of the legend.

        Parameters
        ----------
        state : bool
            Whether mouse dragging is enabled.
        use_blit : bool, optional
            Use blitting for faster image composition. For details see
            :ref:`func-animation`.
        update : {'loc', 'bbox'}, optional
            The legend parameter to be changed when dragged:

            - 'loc': update the *loc* parameter of the legend
            - 'bbox': update the *bbox_to_anchor* parameter of the legend

        Returns
        -------
        If *state* is ``True`` this returns the `~.DraggableLegend` helper
        instance. Otherwise this returns ``None``.
        """
        if state:
            if self._draggable is None:
                self._draggable = DraggableLegend(self,
                                                  use_blit,
                                                  update=update)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None
        return self._draggable

    def get_draggable(self):
        """Return ``True`` if the legend is draggable, ``False`` otherwise."""
        return self._draggable is not None