Source code for matplotlib.legend

The legend module defines the Legend class, which is responsible for
drawing legends associated with axes and/or figures.

.. important::

    It is unlikely that you would ever create a Legend instance manually.
    Most users would normally create a legend via the `~.Axes.legend`
    function. For more details on legends there is also a :doc:`legend guide

The `Legend` class is a container of legend handles and legend texts.

The legend handler map specifies how to create legend handles from artists
(lines, patches, etc.) in the axes or figures. Default legend handlers are
defined in the :mod:`~matplotlib.legend_handler` module. While not all artist
types are covered by the default legend handlers, custom legend handlers can be
defined to support arbitrary objects.

See the :doc:`legend guide </tutorials/intermediate/legend_guide>` for more

import itertools
import logging
import time

import numpy as np

import matplotlib as mpl
from matplotlib import _api, docstring, colors
from matplotlib.artist import Artist, allow_rasterization
from matplotlib.cbook import silent_list
from matplotlib.font_manager import FontProperties
from matplotlib.lines import Line2D
from matplotlib.patches import (Patch, Rectangle, Shadow, FancyBboxPatch,
from matplotlib.collections import (LineCollection, RegularPolyCollection,
                                    CircleCollection, PathCollection,
from matplotlib.transforms import Bbox, BboxBase, TransformedBbox
from matplotlib.transforms import BboxTransformTo, BboxTransformFrom

from matplotlib.offsetbox import HPacker, VPacker, TextArea, DrawingArea
from matplotlib.offsetbox import DraggableOffsetBox

from matplotlib.container import ErrorbarContainer, BarContainer, StemContainer
from . import legend_handler

[docs]class DraggableLegend(DraggableOffsetBox): def __init__(self, legend, use_blit=False, update="loc"): """ Wrapper around a `.Legend` to support mouse dragging. Parameters ---------- legend : `.Legend` The `.Legend` instance to wrap. use_blit : bool, optional Use blitting for faster image composition. For details see :ref:`func-animation`. update : {'loc', 'bbox'}, optional If "loc", update the *loc* parameter of the legend upon finalizing. If "bbox", update the *bbox_to_anchor* parameter. """ self.legend = legend _api.check_in_list(["loc", "bbox"], update=update) self._update = update super().__init__(legend, legend._legend_box, use_blit=use_blit)
[docs] def finalize_offset(self): if self._update == "loc": self._update_loc(self.get_loc_in_canvas()) elif self._update == "bbox": self._bbox_to_anchor(self.get_loc_in_canvas())
def _update_loc(self, loc_in_canvas): bbox = self.legend.get_bbox_to_anchor() # if bbox has zero width or height, the transformation is # ill-defined. Fall back to the default bbox_to_anchor. if bbox.width == 0 or bbox.height == 0: self.legend.set_bbox_to_anchor(None) bbox = self.legend.get_bbox_to_anchor() _bbox_transform = BboxTransformFrom(bbox) self.legend._loc = tuple(_bbox_transform.transform(loc_in_canvas)) def _update_bbox_to_anchor(self, loc_in_canvas): loc_in_bbox = self.legend.axes.transAxes.transform(loc_in_canvas) self.legend.set_bbox_to_anchor(loc_in_bbox)
docstring.interpd.update(_legend_kw_doc=""" loc : str or pair of floats, default: :rc:`legend.loc` ('best' for axes, \ 'upper right' for figures) The location of the legend. The strings ``'upper left', 'upper right', 'lower left', 'lower right'`` place the legend at the corresponding corner of the axes/figure. The strings ``'upper center', 'lower center', 'center left', 'center right'`` place the legend at the center of the corresponding edge of the axes/figure. The string ``'center'`` places the legend at the center of the axes/figure. The string ``'best'`` places the legend at the location, among the nine locations defined so far, with the minimum overlap with other drawn artists. This option can be quite slow for plots with large amounts of data; your plotting speed may benefit from providing a specific location. The location can also be a 2-tuple giving the coordinates of the lower-left corner of the legend in axes coordinates (in which case *bbox_to_anchor* will be ignored). For back-compatibility, ``'center right'`` (but no other location) can also be spelled ``'right'``, and each "string" locations can also be given as a numeric value: =============== ============= Location String Location Code =============== ============= 'best' 0 '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 =============== ============= bbox_to_anchor : `.BboxBase`, 2-tuple, or 4-tuple of floats Box that is used to position the legend in conjunction with *loc*. Defaults to `axes.bbox` (if called as a method to `.Axes.legend`) or `figure.bbox` (if `.Figure.legend`). This argument allows arbitrary placement of the legend. Bbox coordinates are interpreted in the coordinate system given by *bbox_transform*, with the default transform Axes or Figure coordinates, depending on which ``legend`` is called. If a 4-tuple or `.BboxBase` is given, then it specifies the bbox ``(x, y, width, height)`` that the legend is placed in. To put the legend in the best location in the bottom right quadrant of the axes (or figure):: loc='best', bbox_to_anchor=(0.5, 0., 0.5, 0.5) A 2-tuple ``(x, y)`` places the corner of the legend specified by *loc* at x, y. For example, to put the legend's upper right-hand corner in the center of the axes (or figure) the following keywords can be used:: loc='upper right', bbox_to_anchor=(0.5, 0.5) ncol : int, default: 1 The number of columns that the legend has. prop : None or `matplotlib.font_manager.FontProperties` or dict The font properties of the legend. If None (default), the current :data:`matplotlib.rcParams` will be used. fontsize : int or {'xx-small', 'x-small', 'small', 'medium', 'large', \ 'x-large', 'xx-large'} The font size of the legend. If the value is numeric the size will be the absolute font size in points. String values are relative to the current default font size. This argument is only used if *prop* is not specified. labelcolor : str or list The color of the text in the legend. Either a valid color string (for example, 'red'), or a list of color strings. The labelcolor can also be made to match the color of the line or marker using 'linecolor', 'markerfacecolor' (or 'mfc'), or 'markeredgecolor' (or 'mec'). numpoints : int, default: :rc:`legend.numpoints` The number of marker points in the legend when creating a legend entry for a `.Line2D` (line). scatterpoints : int, default: :rc:`legend.scatterpoints` The number of marker points in the legend when creating a legend entry for a `.PathCollection` (scatter plot). scatteryoffsets : iterable of floats, default: ``[0.375, 0.5, 0.3125]`` The vertical offset (relative to the font size) for the markers created for a scatter plot legend entry. 0.0 is at the base the legend text, and 1.0 is at the top. To draw all markers at the same height, set to ``[0.5]``. markerscale : float, default: :rc:`legend.markerscale` The relative size of legend markers compared with the originally drawn ones. markerfirst : bool, default: True If *True*, legend marker is placed to the left of the legend label. If *False*, legend marker is placed to the right of the legend label. frameon : bool, default: :rc:`legend.frameon` Whether the legend should be drawn on a patch (frame). fancybox : bool, default: :rc:`legend.fancybox` Whether round edges should be enabled around the `~.FancyBboxPatch` which makes up the legend's background. shadow : bool, default: :rc:`legend.shadow` Whether to draw a shadow behind the legend. framealpha : float, default: :rc:`legend.framealpha` The alpha transparency of the legend's background. If *shadow* is activated and *framealpha* is ``None``, the default value is ignored. facecolor : "inherit" or color, default: :rc:`legend.facecolor` The legend's background color. If ``"inherit"``, use :rc:`axes.facecolor`. edgecolor : "inherit" or color, default: :rc:`legend.edgecolor` The legend's background patch edge color. If ``"inherit"``, use take :rc:`axes.edgecolor`. mode : {"expand", None} If *mode* is set to ``"expand"`` the legend will be horizontally expanded to fill the axes area (or *bbox_to_anchor* if defines the legend's size). bbox_transform : None or `matplotlib.transforms.Transform` The transform for the bounding box (*bbox_to_anchor*). For a value of ``None`` (default) the Axes' :data:`~matplotlib.axes.Axes.transAxes` transform will be used. title : str or None The legend's title. Default is no title (``None``). title_fontsize : int or {'xx-small', 'x-small', 'small', 'medium', 'large', \ 'x-large', 'xx-large'}, default: :rc:`legend.title_fontsize` The font size of the legend's title. borderpad : float, default: :rc:`legend.borderpad` The fractional whitespace inside the legend border, in font-size units. labelspacing : float, default: :rc:`legend.labelspacing` The vertical space between the legend entries, in font-size units. handlelength : float, default: :rc:`legend.handlelength` The length of the legend handles, in font-size units. handletextpad : float, default: :rc:`legend.handletextpad` The pad between the legend handle and text, in font-size units. borderaxespad : float, default: :rc:`legend.borderaxespad` The pad between the axes and legend border, in font-size units. columnspacing : float, default: :rc:`legend.columnspacing` The spacing between columns, in font-size units. handler_map : dict or None The custom dictionary mapping instances or types to a legend handler. This *handler_map* updates the default handler map found at `matplotlib.legend.Legend.get_legend_handler_map`. """)
[docs]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 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 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('_'): _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, 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 raise ValueError( "Unrecognized location {!r}. Valid locations are\n\t{}\n" .format(loc, '\n\t'.join( else: 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 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 # 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
[docs] @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.
[docs] @classmethod def get_default_handler_map(cls): """ A class method that returns the default handler map. """ return cls._default_handler_map
[docs] @classmethod def set_default_handler_map(cls, handler_map): """ A class method to set the default handler map. """ cls._default_handler_map = handler_map
[docs] @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)
[docs] 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
[docs] @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: _api.warn_external( "Legend does not support {!r} instances.\nA proxy artist " "may be used instead.\nSee: " "" "#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.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
[docs] def get_children(self): # docstring inherited return [self._legend_box, self.get_frame()]
[docs] def get_frame(self): """Return the `~.patches.Rectangle` used to frame the legend.""" return self.legendPatch
[docs] 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)]
[docs] 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)])
[docs] def get_texts(self): r"""Return the list of `~.text.Text`\s in the legend.""" return silent_list('Text', self.texts)
[docs] 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
[docs] def get_title(self): """Return the `.Text` instance for the legend title.""" return self._legend_title_box._text
[docs] 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)
[docs] 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)
[docs] def get_frame_on(self): """Get whether the legend box patch is drawn.""" return self.legendPatch.get_visible()
[docs] 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.
[docs] 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
[docs] 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(] 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
[docs] def contains(self, event): inside, info = self._default_contains(event) if inside is not None: return inside, info return self.legendPatch.contains(event)
[docs] 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
[docs] def get_draggable(self): """Return ``True`` if the legend is draggable, ``False`` otherwise.""" return self._draggable is not None
# Helper functions to parse legend arguments for both `figure.legend` and # `axes.legend`: def _get_legend_handles(axs, legend_handler_map=None): """ Return a generator of artists that can be used as handles in a legend. """ handles_original = [] for ax in axs: handles_original += (ax.lines + ax.patches + ax.collections + ax.containers) # support parasite axes: if hasattr(ax, 'parasites'): for axx in ax.parasites: handles_original += (axx.lines + axx.patches + axx.collections + axx.containers) handler_map = Legend.get_default_handler_map() if legend_handler_map is not None: handler_map = handler_map.copy() handler_map.update(legend_handler_map) has_handler = Legend.get_legend_handler for handle in handles_original: label = handle.get_label() if label != '_nolegend_' and has_handler(handler_map, handle): yield handle def _get_legend_handles_labels(axs, legend_handler_map=None): """ Return handles and labels for legend, internal method. """ handles = [] labels = [] for handle in _get_legend_handles(axs, legend_handler_map): label = handle.get_label() if label and not label.startswith('_'): handles.append(handle) labels.append(label) return handles, labels def _parse_legend_args(axs, *args, handles=None, labels=None, **kwargs): """ Get the handles and labels from the calls to either ``figure.legend`` or ``axes.legend``. The parser is a bit involved because we support:: legend() legend(labels) legend(handles, labels) legend(labels=labels) legend(handles=handles) legend(handles=handles, labels=labels) The behavior for a mixture of positional and keyword handles and labels is undefined and issues a warning. Parameters ---------- axs : list of `.Axes` If handles are not given explicitly, the artists in these Axes are used as handles. *args : tuple Positional parameters passed to ``legend()``. handles The value of the keyword argument ``legend(handles=...)``, or *None* if that keyword argument was not used. labels The value of the keyword argument ``legend(labels=...)``, or *None* if that keyword argument was not used. **kwargs All other keyword arguments passed to ``legend()``. Returns ------- handles : list of `.Artist` The legend handles. labels : list of str The legend labels. extra_args : tuple *args* with positional handles and labels removed. kwargs : dict *kwargs* with keywords handles and labels removed. """ log = logging.getLogger(__name__) handlers = kwargs.get('handler_map', {}) or {} extra_args = () if (handles is not None or labels is not None) and args: _api.warn_external("You have mixed positional and keyword arguments, " "some input may be discarded.") # if got both handles and labels as kwargs, make same length if handles and labels: handles, labels = zip(*zip(handles, labels)) elif handles is not None and labels is None: labels = [handle.get_label() for handle in handles] elif labels is not None and handles is None: # Get as many handles as there are labels. handles = [handle for handle, label in zip(_get_legend_handles(axs, handlers), labels)] # No arguments - automatically detect labels and handles. elif len(args) == 0: handles, labels = _get_legend_handles_labels(axs, handlers) if not handles: log.warning('No handles with labels found to put in legend.') # One argument. User defined labels - automatic handle detection. elif len(args) == 1: labels, = args if any(isinstance(l, Artist) for l in labels): raise TypeError("A single argument passed to legend() must be a " "list of labels, but found an Artist in there.") # Get as many handles as there are labels. handles = [handle for handle, label in zip(_get_legend_handles(axs, handlers), labels)] # Two arguments: # * user defined handles and labels elif len(args) >= 2: handles, labels = args[:2] extra_args = args[2:] else: raise TypeError('Invalid arguments to legend.') return handles, labels, extra_args, kwargs