def tripcolor(ax, *args, alpha=1.0, norm=None, cmap=None, vmin=None, vmax=None, shading='flat', facecolors=None, **kwargs): """ Create a pseudocolor plot of an unstructured triangular grid. The triangulation can be specified in one of two ways; either:: tripcolor(triangulation, ...) where triangulation is a `.Triangulation` object, or :: tripcolor(x, y, ...) tripcolor(x, y, triangles, ...) tripcolor(x, y, triangles=triangles, ...) tripcolor(x, y, mask=mask, ...) tripcolor(x, y, triangles, mask=mask, ...) in which case a Triangulation object will be created. See `.Triangulation` for a explanation of these possibilities. The next argument must be *C*, the array of color values, either one per point in the triangulation if color values are defined at points, or one per triangle in the triangulation if color values are defined at triangles. If there are the same number of points and triangles in the triangulation it is assumed that color values are defined at points; to force the use of color values at triangles use the kwarg ``facecolors=C`` instead of just ``C``. *shading* may be 'flat' (the default) or 'gouraud'. If *shading* is 'flat' and C values are defined at points, the color values used for each triangle are from the mean C of the triangle's three points. If *shading* is 'gouraud' then color values must be defined at points. The remaining kwargs are the same as for `~.Axes.pcolor`. """ _api.check_in_list(['flat', 'gouraud'], shading=shading) tri, args, kwargs = Triangulation.get_from_args_and_kwargs(*args, **kwargs) # C is the colors array defined at either points or faces (i.e. triangles). # If facecolors is None, C are defined at points. # If facecolors is not None, C are defined at faces. if facecolors is not None: C = facecolors else: C = np.asarray(args[0]) # If there are a different number of points and triangles in the # triangulation, can omit facecolors kwarg as it is obvious from # length of C whether it refers to points or faces. # Do not do this for gouraud shading. if (facecolors is None and len(C) == len(tri.triangles) and len(C) != len(tri.x) and shading != 'gouraud'): facecolors = C # Check length of C is OK. if ((facecolors is None and len(C) != len(tri.x)) or (facecolors is not None and len(C) != len(tri.triangles))): raise ValueError('Length of color values array must be the same ' 'as either the number of triangulation points ' 'or triangles') # Handling of linewidths, shading, edgecolors and antialiased as # in Axes.pcolor linewidths = (0.25, ) if 'linewidth' in kwargs: kwargs['linewidths'] = kwargs.pop('linewidth') kwargs.setdefault('linewidths', linewidths) edgecolors = 'none' if 'edgecolor' in kwargs: kwargs['edgecolors'] = kwargs.pop('edgecolor') ec = kwargs.setdefault('edgecolors', edgecolors) if 'antialiased' in kwargs: kwargs['antialiaseds'] = kwargs.pop('antialiased') if 'antialiaseds' not in kwargs and ec.lower() == "none": kwargs['antialiaseds'] = False if shading == 'gouraud': if facecolors is not None: raise ValueError('Gouraud shading does not support the use ' 'of facecolors kwarg') if len(C) != len(tri.x): raise ValueError('For gouraud shading, the length of color ' 'values array must be the same as the ' 'number of triangulation points') collection = TriMesh(tri, **kwargs) else: # Vertices of triangles. maskedTris = tri.get_masked_triangles() verts = np.stack((tri.x[maskedTris], tri.y[maskedTris]), axis=-1) # Color values. if facecolors is None: # One color per triangle, the mean of the 3 vertex color values. C = C[maskedTris].mean(axis=1) elif tri.mask is not None: # Remove color values of masked triangles. C = C[~tri.mask] collection = PolyCollection(verts, **kwargs) collection.set_alpha(alpha) collection.set_array(C) _api.check_isinstance((Normalize, None), norm=norm) collection.set_cmap(cmap) collection.set_norm(norm) collection._scale_norm(norm, vmin, vmax) ax.grid(False) minx = tri.x.min() maxx = tri.x.max() miny = tri.y.min() maxy = tri.y.max() corners = (minx, miny), (maxx, maxy) ax.update_datalim(corners) ax.autoscale_view() ax.add_collection(collection) return collection
def tripcolor(ax, *args, alpha=1.0, norm=None, cmap=None, vmin=None, vmax=None, shading='flat', facecolors=None, **kwargs): """ Create a pseudocolor plot of an unstructured triangular grid. Call signatures:: tripcolor(triangulation, C, *, ...) tripcolor(x, y, C, *, [triangles=triangles], [mask=mask], ...) The triangular grid can be specified either by passing a `.Triangulation` object as the first parameter, or by passing the points *x*, *y* and optionally the *triangles* and a *mask*. See `.Triangulation` for an explanation of these parameters. If neither of *triangulation* or *triangles* are given, the triangulation is calculated on the fly. In this case, it does not make sense to provide colors at the triangle faces via *C* or *facecolors* because there are multiple possible triangulations for a group of points and you don't know which triangles will be constructed. Parameters ---------- triangulation : `.Triangulation` An already created triangular grid. x, y, triangles, mask Parameters defining the triangular grid. See `.Triangulation`. This is mutually exclusive with specifying *triangulation*. C : array-like The color values, either for the points or for the triangles. Which one is automatically inferred from the length of *C*, i.e. does it match the number of points or the number of triangles. If there are the same number of points and triangles in the triangulation it is assumed that color values are defined at points; to force the use of color values at triangles use the keyword argument ``facecolors=C`` instead of just ``C``. This parameter is position-only. facecolors : array-like, optional Can be used alternatively to *C* to specify colors at the triangle faces. This parameter takes precedence over *C*. shading : {'flat', 'gouraud'}, default: 'flat' If 'flat' and the color values *C* are defined at points, the color values used for each triangle are from the mean C of the triangle's three points. If *shading* is 'gouraud' then color values must be defined at points. other_parameters All other parameters are the same as for `~.Axes.pcolor`. Notes ----- It is possible to pass the triangles positionally, i.e. ``tripcolor(x, y, triangles, C, ...)``. However, this is discouraged. For more clarity, pass *triangles* via keyword argument. """ _api.check_in_list(['flat', 'gouraud'], shading=shading) tri, args, kwargs = Triangulation.get_from_args_and_kwargs(*args, **kwargs) # Parse the color to be in one of (the other variable will be None): # - facecolors: if specified at the triangle faces # - point_colors: if specified at the points if facecolors is not None: if args: _api.warn_external( "Positional parameter C has no effect when the keyword " "facecolors is given") point_colors = None if len(facecolors) != len(tri.triangles): raise ValueError("The length of facecolors must match the number " "of triangles") else: # Color from positional parameter C if not args: raise ValueError( "Missing color parameter. Please pass C positionally or " "facecolors via keyword") elif len(args) > 1: _api.warn_external( "Additional positional parameters {args[1:]!r} are ignored") C = np.asarray(args[0]) if len(C) == len(tri.x): # having this before the len(tri.triangles) comparison gives # precedence to nodes if there are as many nodes as triangles point_colors = C facecolors = None elif len(C) == len(tri.triangles): point_colors = None facecolors = C else: raise ValueError('The length of C must match either the number ' 'of points or the number of triangles') # Handling of linewidths, shading, edgecolors and antialiased as # in Axes.pcolor linewidths = (0.25, ) if 'linewidth' in kwargs: kwargs['linewidths'] = kwargs.pop('linewidth') kwargs.setdefault('linewidths', linewidths) edgecolors = 'none' if 'edgecolor' in kwargs: kwargs['edgecolors'] = kwargs.pop('edgecolor') ec = kwargs.setdefault('edgecolors', edgecolors) if 'antialiased' in kwargs: kwargs['antialiaseds'] = kwargs.pop('antialiased') if 'antialiaseds' not in kwargs and ec.lower() == "none": kwargs['antialiaseds'] = False _api.check_isinstance((Normalize, None), norm=norm) if shading == 'gouraud': if facecolors is not None: raise ValueError( "shading='gouraud' can only be used when the colors " "are specified at the points, not at the faces.") collection = TriMesh(tri, alpha=alpha, array=point_colors, cmap=cmap, norm=norm, **kwargs) else: # Vertices of triangles. maskedTris = tri.get_masked_triangles() verts = np.stack((tri.x[maskedTris], tri.y[maskedTris]), axis=-1) # Color values. if facecolors is None: # One color per triangle, the mean of the 3 vertex color values. colors = point_colors[maskedTris].mean(axis=1) elif tri.mask is not None: # Remove color values of masked triangles. colors = facecolors[~tri.mask] else: colors = facecolors collection = PolyCollection(verts, alpha=alpha, array=colors, cmap=cmap, norm=norm, **kwargs) collection._scale_norm(norm, vmin, vmax) ax.grid(False) minx = tri.x.min() maxx = tri.x.max() miny = tri.y.min() maxy = tri.y.max() corners = (minx, miny), (maxx, maxy) ax.update_datalim(corners) ax.autoscale_view() ax.add_collection(collection) return collection