Version 3.0.0
matplotlib
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Source code for matplotlib.legend_handler

"""
This module defines default legend handlers.

It is strongly encouraged to have read the :doc:`legend guide
</tutorials/intermediate/legend_guide>` before this documentation.

Legend handlers are expected to be a callable object with a following
signature. ::

    legend_handler(legend, orig_handle, fontsize, handlebox)

Where *legend* is the legend itself, *orig_handle* is the original
plot, *fontsize* is the fontsize in pixels, and *handlebox* is a
OffsetBox instance. Within the call, you should create relevant
artists (using relevant properties from the *legend* and/or
*orig_handle*) and add them into the handlebox. The artists needs to
be scaled according to the fontsize (note that the size is in pixel,
i.e., this is dpi-scaled value).

This module includes definition of several legend handler classes
derived from the base class (HandlerBase) with the following method::

    def legend_artist(self, legend, orig_handle, fontsize, handlebox):

"""

from itertools import cycle

import numpy as np

from matplotlib.lines import Line2D
from matplotlib.patches import Rectangle
import matplotlib.collections as mcoll
import matplotlib.colors as mcolors


[docs]def update_from_first_child(tgt, src): tgt.update_from(src.get_children()[0])
[docs]class HandlerBase(object): """ A Base class for default legend handlers. The derived classes are meant to override *create_artists* method, which has a following signature.:: def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): The overridden method needs to create artists of the given transform that fits in the given dimension (xdescent, ydescent, width, height) that are scaled by fontsize if necessary. """ def __init__(self, xpad=0., ypad=0., update_func=None): self._xpad, self._ypad = xpad, ypad self._update_prop_func = update_func def _update_prop(self, legend_handle, orig_handle): if self._update_prop_func is None: self._default_update_prop(legend_handle, orig_handle) else: self._update_prop_func(legend_handle, orig_handle) def _default_update_prop(self, legend_handle, orig_handle): legend_handle.update_from(orig_handle)
[docs] def update_prop(self, legend_handle, orig_handle, legend): self._update_prop(legend_handle, orig_handle) legend._set_artist_props(legend_handle) legend_handle.set_clip_box(None) legend_handle.set_clip_path(None)
[docs] def adjust_drawing_area(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, ): xdescent = xdescent - self._xpad * fontsize ydescent = ydescent - self._ypad * fontsize width = width - self._xpad * fontsize height = height - self._ypad * fontsize return xdescent, ydescent, width, height
[docs] def legend_artist(self, legend, orig_handle, fontsize, handlebox): """ Return the artist that this HandlerBase generates for the given original artist/handle. Parameters ---------- legend : :class:`matplotlib.legend.Legend` instance The legend for which these legend artists are being created. orig_handle : :class:`matplotlib.artist.Artist` or similar The object for which these legend artists are being created. fontsize : float or int The fontsize in pixels. The artists being created should be scaled according to the given fontsize. handlebox : :class:`matplotlib.offsetbox.OffsetBox` instance The box which has been created to hold this legend entry's artists. Artists created in the `legend_artist` method must be added to this handlebox inside this method. """ xdescent, ydescent, width, height = self.adjust_drawing_area( legend, orig_handle, handlebox.xdescent, handlebox.ydescent, handlebox.width, handlebox.height, fontsize) artists = self.create_artists(legend, orig_handle, xdescent, ydescent, width, height, fontsize, handlebox.get_transform()) # create_artists will return a list of artists. for a in artists: handlebox.add_artist(a) # we only return the first artist return artists[0]
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): raise NotImplementedError('Derived must override')
[docs]class HandlerNpoints(HandlerBase): """ A legend handler that shows *numpoints* points in the legend entry. """ def __init__(self, marker_pad=0.3, numpoints=None, **kw): """ Parameters ---------- marker_pad : float Padding between points in legend entry. numpoints : int Number of points to show in legend entry. Notes ----- Any other keyword arguments are given to `HandlerBase`. """ HandlerBase.__init__(self, **kw) self._numpoints = numpoints self._marker_pad = marker_pad
[docs] def get_numpoints(self, legend): if self._numpoints is None: return legend.numpoints else: return self._numpoints
[docs] def get_xdata(self, legend, xdescent, ydescent, width, height, fontsize): numpoints = self.get_numpoints(legend) if numpoints > 1: # we put some pad here to compensate the size of the marker pad = self._marker_pad * fontsize xdata = np.linspace(-xdescent + pad, -xdescent + width - pad, numpoints) xdata_marker = xdata else: xdata = np.linspace(-xdescent, -xdescent + width, 2) xdata_marker = [-xdescent + 0.5 * width] return xdata, xdata_marker
[docs]class HandlerNpointsYoffsets(HandlerNpoints): """ A legend handler that shows *numpoints* in the legend, and allows them to be individually offest in the y-direction. """ def __init__(self, numpoints=None, yoffsets=None, **kw): """ Parameters ---------- numpoints : int Number of points to show in legend entry. yoffsets : array of floats Length *numpoints* list of y offsets for each point in legend entry. Notes ----- Any other keyword arguments are given to `HandlerNpoints`. """ HandlerNpoints.__init__(self, numpoints=numpoints, **kw) self._yoffsets = yoffsets
[docs] def get_ydata(self, legend, xdescent, ydescent, width, height, fontsize): if self._yoffsets is None: ydata = height * legend._scatteryoffsets else: ydata = height * np.asarray(self._yoffsets) return ydata
[docs]class HandlerLine2D(HandlerNpoints): """ Handler for `.Line2D` instances. """ def __init__(self, marker_pad=0.3, numpoints=None, **kw): """ Parameters ---------- marker_pad : float Padding between points in legend entry. numpoints : int Number of points to show in legend entry. Notes ----- Any other keyword arguments are given to `HandlerNpoints`. """ HandlerNpoints.__init__(self, marker_pad=marker_pad, numpoints=numpoints, **kw)
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): xdata, xdata_marker = self.get_xdata(legend, xdescent, ydescent, width, height, fontsize) ydata = ((height - ydescent) / 2.) * np.ones(xdata.shape, float) legline = Line2D(xdata, ydata) self.update_prop(legline, orig_handle, legend) legline.set_drawstyle('default') legline.set_marker("") legline_marker = Line2D(xdata_marker, ydata[:len(xdata_marker)]) self.update_prop(legline_marker, orig_handle, legend) legline_marker.set_linestyle('None') if legend.markerscale != 1: newsz = legline_marker.get_markersize() * legend.markerscale legline_marker.set_markersize(newsz) # we don't want to add this to the return list because # the texts and handles are assumed to be in one-to-one # correspondence. legline._legmarker = legline_marker legline.set_transform(trans) legline_marker.set_transform(trans) return [legline, legline_marker]
[docs]class HandlerPatch(HandlerBase): """ Handler for `.Patch` instances. """ def __init__(self, patch_func=None, **kw): """ Parameters ---------- patch_func : callable, optional The function that creates the legend key artist. *patch_func* should have the signature:: def patch_func(legend=legend, orig_handle=orig_handle, xdescent=xdescent, ydescent=ydescent, width=width, height=height, fontsize=fontsize) Subsequently the created artist will have its ``update_prop`` method called and the appropriate transform will be applied. Notes ----- Any other keyword arguments are given to `HandlerBase`. """ HandlerBase.__init__(self, **kw) self._patch_func = patch_func def _create_patch(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize): if self._patch_func is None: p = Rectangle(xy=(-xdescent, -ydescent), width=width, height=height) else: p = self._patch_func(legend=legend, orig_handle=orig_handle, xdescent=xdescent, ydescent=ydescent, width=width, height=height, fontsize=fontsize) return p
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): p = self._create_patch(legend, orig_handle, xdescent, ydescent, width, height, fontsize) self.update_prop(p, orig_handle, legend) p.set_transform(trans) return [p]
[docs]class HandlerLineCollection(HandlerLine2D): """ Handler for `.LineCollection` instances. """
[docs] def get_numpoints(self, legend): if self._numpoints is None: return legend.scatterpoints else: return self._numpoints
def _default_update_prop(self, legend_handle, orig_handle): lw = orig_handle.get_linewidths()[0] dashes = orig_handle._us_linestyles[0] color = orig_handle.get_colors()[0] legend_handle.set_color(color) legend_handle.set_linestyle(dashes) legend_handle.set_linewidth(lw)
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): xdata, xdata_marker = self.get_xdata(legend, xdescent, ydescent, width, height, fontsize) ydata = ((height - ydescent) / 2.) * np.ones(xdata.shape, float) legline = Line2D(xdata, ydata) self.update_prop(legline, orig_handle, legend) legline.set_transform(trans) return [legline]
[docs]class HandlerRegularPolyCollection(HandlerNpointsYoffsets): """ Handler for `.RegularPolyCollections`. """ def __init__(self, yoffsets=None, sizes=None, **kw): HandlerNpointsYoffsets.__init__(self, yoffsets=yoffsets, **kw) self._sizes = sizes
[docs] def get_numpoints(self, legend): if self._numpoints is None: return legend.scatterpoints else: return self._numpoints
[docs] def get_sizes(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize): if self._sizes is None: handle_sizes = orig_handle.get_sizes() if not len(handle_sizes): handle_sizes = [1] size_max = max(handle_sizes) * legend.markerscale ** 2 size_min = min(handle_sizes) * legend.markerscale ** 2 numpoints = self.get_numpoints(legend) if numpoints < 4: sizes = [.5 * (size_max + size_min), size_max, size_min][:numpoints] else: rng = (size_max - size_min) sizes = rng * np.linspace(0, 1, numpoints) + size_min else: sizes = self._sizes return sizes
[docs] def update_prop(self, legend_handle, orig_handle, legend): self._update_prop(legend_handle, orig_handle) legend_handle.set_figure(legend.figure) #legend._set_artist_props(legend_handle) legend_handle.set_clip_box(None) legend_handle.set_clip_path(None)
[docs] def create_collection(self, orig_handle, sizes, offsets, transOffset): p = type(orig_handle)(orig_handle.get_numsides(), rotation=orig_handle.get_rotation(), sizes=sizes, offsets=offsets, transOffset=transOffset, ) return p
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): xdata, xdata_marker = self.get_xdata(legend, xdescent, ydescent, width, height, fontsize) ydata = self.get_ydata(legend, xdescent, ydescent, width, height, fontsize) sizes = self.get_sizes(legend, orig_handle, xdescent, ydescent, width, height, fontsize) p = self.create_collection(orig_handle, sizes, offsets=list(zip(xdata_marker, ydata)), transOffset=trans) self.update_prop(p, orig_handle, legend) p._transOffset = trans return [p]
[docs]class HandlerPathCollection(HandlerRegularPolyCollection): """ Handler for `.PathCollections`, which are used by `~.Axes.scatter`. """
[docs] def create_collection(self, orig_handle, sizes, offsets, transOffset): p = type(orig_handle)([orig_handle.get_paths()[0]], sizes=sizes, offsets=offsets, transOffset=transOffset, ) return p
[docs]class HandlerCircleCollection(HandlerRegularPolyCollection): """ Handler for `.CircleCollections`. """
[docs] def create_collection(self, orig_handle, sizes, offsets, transOffset): p = type(orig_handle)(sizes, offsets=offsets, transOffset=transOffset, ) return p
[docs]class HandlerErrorbar(HandlerLine2D): """ Handler for Errorbars. """ def __init__(self, xerr_size=0.5, yerr_size=None, marker_pad=0.3, numpoints=None, **kw): self._xerr_size = xerr_size self._yerr_size = yerr_size HandlerLine2D.__init__(self, marker_pad=marker_pad, numpoints=numpoints, **kw)
[docs] def get_err_size(self, legend, xdescent, ydescent, width, height, fontsize): xerr_size = self._xerr_size * fontsize if self._yerr_size is None: yerr_size = xerr_size else: yerr_size = self._yerr_size * fontsize return xerr_size, yerr_size
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): plotlines, caplines, barlinecols = orig_handle xdata, xdata_marker = self.get_xdata(legend, xdescent, ydescent, width, height, fontsize) ydata = ((height - ydescent) / 2.) * np.ones(xdata.shape, float) legline = Line2D(xdata, ydata) xdata_marker = np.asarray(xdata_marker) ydata_marker = np.asarray(ydata[:len(xdata_marker)]) xerr_size, yerr_size = self.get_err_size(legend, xdescent, ydescent, width, height, fontsize) legline_marker = Line2D(xdata_marker, ydata_marker) # when plotlines are None (only errorbars are drawn), we just # make legline invisible. if plotlines is None: legline.set_visible(False) legline_marker.set_visible(False) else: self.update_prop(legline, plotlines, legend) legline.set_drawstyle('default') legline.set_marker('None') self.update_prop(legline_marker, plotlines, legend) legline_marker.set_linestyle('None') if legend.markerscale != 1: newsz = legline_marker.get_markersize() * legend.markerscale legline_marker.set_markersize(newsz) handle_barlinecols = [] handle_caplines = [] if orig_handle.has_xerr: verts = [ ((x - xerr_size, y), (x + xerr_size, y)) for x, y in zip(xdata_marker, ydata_marker)] coll = mcoll.LineCollection(verts) self.update_prop(coll, barlinecols[0], legend) handle_barlinecols.append(coll) if caplines: capline_left = Line2D(xdata_marker - xerr_size, ydata_marker) capline_right = Line2D(xdata_marker + xerr_size, ydata_marker) self.update_prop(capline_left, caplines[0], legend) self.update_prop(capline_right, caplines[0], legend) capline_left.set_marker("|") capline_right.set_marker("|") handle_caplines.append(capline_left) handle_caplines.append(capline_right) if orig_handle.has_yerr: verts = [ ((x, y - yerr_size), (x, y + yerr_size)) for x, y in zip(xdata_marker, ydata_marker)] coll = mcoll.LineCollection(verts) self.update_prop(coll, barlinecols[0], legend) handle_barlinecols.append(coll) if caplines: capline_left = Line2D(xdata_marker, ydata_marker - yerr_size) capline_right = Line2D(xdata_marker, ydata_marker + yerr_size) self.update_prop(capline_left, caplines[0], legend) self.update_prop(capline_right, caplines[0], legend) capline_left.set_marker("_") capline_right.set_marker("_") handle_caplines.append(capline_left) handle_caplines.append(capline_right) artists = [] artists.extend(handle_barlinecols) artists.extend(handle_caplines) artists.append(legline) artists.append(legline_marker) for artist in artists: artist.set_transform(trans) return artists
[docs]class HandlerStem(HandlerNpointsYoffsets): """ Handler for plots produced by `~.Axes.stem`. """ def __init__(self, marker_pad=0.3, numpoints=None, bottom=None, yoffsets=None, **kw): """ Parameters ---------- marker_pad : float Padding between points in legend entry. Default is 0.3. numpoints : int, optional Number of points to show in legend entry. bottom : float, optional yoffsets : array of floats, optional Length *numpoints* list of y offsets for each point in legend entry. Notes ----- Any other keyword arguments are given to `HandlerNpointsYoffsets`. """ HandlerNpointsYoffsets.__init__(self, marker_pad=marker_pad, numpoints=numpoints, yoffsets=yoffsets, **kw) self._bottom = bottom
[docs] def get_ydata(self, legend, xdescent, ydescent, width, height, fontsize): if self._yoffsets is None: ydata = height * (0.5 * legend._scatteryoffsets + 0.5) else: ydata = height * np.asarray(self._yoffsets) return ydata
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): markerline, stemlines, baseline = orig_handle xdata, xdata_marker = self.get_xdata(legend, xdescent, ydescent, width, height, fontsize) ydata = self.get_ydata(legend, xdescent, ydescent, width, height, fontsize) if self._bottom is None: bottom = 0. else: bottom = self._bottom leg_markerline = Line2D(xdata_marker, ydata[:len(xdata_marker)]) self.update_prop(leg_markerline, markerline, legend) leg_stemlines = [] for thisx, thisy in zip(xdata_marker, ydata): l = Line2D([thisx, thisx], [bottom, thisy]) leg_stemlines.append(l) for lm, m in zip(leg_stemlines, stemlines): self.update_prop(lm, m, legend) leg_baseline = Line2D([np.min(xdata), np.max(xdata)], [bottom, bottom]) self.update_prop(leg_baseline, baseline, legend) artists = [leg_markerline] artists.extend(leg_stemlines) artists.append(leg_baseline) for artist in artists: artist.set_transform(trans) return artists
[docs]class HandlerTuple(HandlerBase): """ Handler for Tuple. Additional kwargs are passed through to `HandlerBase`. Parameters ---------- ndivide : int, optional The number of sections to divide the legend area into. If None, use the length of the input tuple. Default is 1. pad : float, optional If None, fall back to ``legend.borderpad`` as the default. In units of fraction of font size. Default is None. """ def __init__(self, ndivide=1, pad=None, **kwargs): self._ndivide = ndivide self._pad = pad HandlerBase.__init__(self, **kwargs)
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): handler_map = legend.get_legend_handler_map() if self._ndivide is None: ndivide = len(orig_handle) else: ndivide = self._ndivide if self._pad is None: pad = legend.borderpad * fontsize else: pad = self._pad * fontsize if ndivide > 1: width = (width - pad * (ndivide - 1)) / ndivide xds_cycle = cycle(xdescent - (width + pad) * np.arange(ndivide)) a_list = [] for handle1 in orig_handle: handler = legend.get_legend_handler(handler_map, handle1) _a_list = handler.create_artists( legend, handle1, next(xds_cycle), ydescent, width, height, fontsize, trans) a_list.extend(_a_list) return a_list
[docs]class HandlerPolyCollection(HandlerBase): """ Handler for `.PolyCollection` used in `~.Axes.fill_between` and `~.Axes.stackplot`. """ def _update_prop(self, legend_handle, orig_handle): def first_color(colors): if colors is None: return None colors = mcolors.to_rgba_array(colors) if len(colors): return colors[0] else: return "none" def get_first(prop_array): if len(prop_array): return prop_array[0] else: return None edgecolor = getattr(orig_handle, '_original_edgecolor', orig_handle.get_edgecolor()) legend_handle.set_edgecolor(first_color(edgecolor)) facecolor = getattr(orig_handle, '_original_facecolor', orig_handle.get_facecolor()) legend_handle.set_facecolor(first_color(facecolor)) legend_handle.set_fill(orig_handle.get_fill()) legend_handle.set_hatch(orig_handle.get_hatch()) legend_handle.set_linewidth(get_first(orig_handle.get_linewidths())) legend_handle.set_linestyle(get_first(orig_handle.get_linestyles())) legend_handle.set_transform(get_first(orig_handle.get_transforms())) legend_handle.set_figure(orig_handle.get_figure()) legend_handle.set_alpha(orig_handle.get_alpha())
[docs] def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): p = Rectangle(xy=(-xdescent, -ydescent), width=width, height=height) self.update_prop(p, orig_handle, legend) p.set_transform(trans) return [p]