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
labelcolor=None, # keyword to set the text color
# 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, # the font size for the title
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 : 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 therefrom) 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 Figure
Artist.__init__(self)
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
locals_view = locals()
for name in ["numpoints", "markerscale", "shadow", "columnspacing",
"scatterpoints", "handleheight", 'borderpad',
'labelspacing', 'handlelength', 'handletextpad',
'borderaxespad']:
if locals_view[name] is None:
value = mpl.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 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, 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 = mpl.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:
raise ValueError(
"Unrecognized location {!r}. Valid locations are\n\t{}\n"
.format(loc, '\n\t'.join(self.codes)))
else:
loc = self.codes[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 fontsize:
if title_fontsize is None:
title_fontsize = mpl.rcParams['legend.title_fontsize']
tprop = FontProperties(size=title_fontsize)
self.set_title(title, prop=tprop)
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:
pass
elif 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 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(),
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``.
"""
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 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 * 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:
cbook._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,
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):
"""
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
ax = self.parent
lines = [line.get_transform().transform_path(line.get_path())
for line in ax.lines]
bboxes = [patch.get_bbox().transformed(patch.get_data_transform())
if isinstance(patch, Rectangle) else
patch.get_path().get_extents(patch.get_transform())
for patch in ax.patches]
offsets = []
for handle in ax.collections:
_, transOffset, hoffsets, _ = handle._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.
"""
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 # 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:
cbook._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
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(f"The label {label!r} of {handle!r} starts "
"with '_'. It is thus excluded from the "
"legend.")
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(f"Invalid labelcolor: {labelcolor!r}")
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.bounds)
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 a HPacker packed with:
# - handlebox: a DrawingArea which contains the legend handle.
# - labelbox: a TextArea which contains the legend text.
text_list = [] # the list of text instances
handle_list = [] # the list of handle instances
handles_and_labels = []
# 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) # heuristic.
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, label 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 handles for {0} "
"instances.\nA proxy artist may be used "
"instead.\nSee: https://matplotlib.org/"
"stable/tutorials/intermediate/legend_guide.html"
"#controlling-the-legend-entries".format(
type(orig_handle).__name__))
# No handle for this artist, so we just defer to None.
handle_list.append(None)
else:
textbox = TextArea(label,
multilinebaseline=True,
textprops=dict(verticalalignment='baseline',
horizontalalignment='left',
fontproperties=self.prop))
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))
columnbox = []
# array_split splits n handles_and_labels into ncol columns, with the
# first n%ncol columns having an extra entry. filter(len, ...) handles
# the case where n < ncol: the last ncol-n columns are empty and get
# filtered out.
for handles_and_labels_column \
in filter(len, np.array_split(handles_and_labels, self._ncol)):
# 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_column
]
# 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):
_, offset_trf, hoffsets, _ = artist._prepare_points()
for offset in offset_trf.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):
# docstring inherited
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(f"Invalid bbox: {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
