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legend.py
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legend.py
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"""
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 :ref:`legend guide
<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 :ref`<legend_guide>` for more
information.
"""
import itertools
import logging
import numbers
import time
import numpy as np
import matplotlib as mpl
from matplotlib import _api, _docstring, colors, offsetbox
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,
StepPatch)
from matplotlib.collections import (
Collection, CircleCollection, LineCollection, PathCollection,
PolyCollection, RegularPolyCollection)
from matplotlib.text import Text
from matplotlib.transforms import Bbox, BboxBase, TransformedBbox
from matplotlib.transforms import BboxTransformTo, BboxTransformFrom
from matplotlib.offsetbox import (
AnchoredOffsetbox, DraggableOffsetBox,
HPacker, VPacker,
DrawingArea, TextArea,
)
from matplotlib.container import ErrorbarContainer, BarContainer, StemContainer
from . import legend_handler
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)
def finalize_offset(self):
if self._update == "loc":
self._update_loc(self.get_loc_in_canvas())
elif self._update == "bbox":
self._update_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)
_legend_kw_doc_base = """
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)
ncols : int, default: 1
The number of columns that the legend has.
For backward compatibility, the spelling *ncol* is also supported
but it is discouraged. If both are given, *ncols* takes precedence.
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, default: :rc:`legend.labelcolor`
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').
Labelcolor can be set globally using :rc:`legend.labelcolor`. If None,
use :rc:`text.color`.
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 to 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.
reverse : bool, default: False
If *True*, the legend labels are displayed in reverse order from the input.
If *False*, the legend labels are displayed in the same order as the input.
.. versionadded:: 3.7
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 : None, bool or dict, default: :rc:`legend.shadow`
Whether to draw a shadow behind the legend.
The shadow can be configured using `.Patch` keywords.
Customization via :rc:`legend.shadow` is currently not supported.
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_fontproperties : None or `~matplotlib.font_manager.FontProperties` or dict
The font properties of the legend's title. If None (default), the
*title_fontsize* argument will be used if present; if *title_fontsize* is
also None, the current :rc:`legend.title_fontsize` will be used.
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.
Note: This cannot be combined with *title_fontproperties*. If you want
to set the fontsize alongside other font properties, use the *size*
parameter in *title_fontproperties*.
alignment : {'center', 'left', 'right'}, default: 'center'
The alignment of the legend title and the box of entries. The entries
are aligned as a single block, so that markers always lined up.
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.
handleheight : float, default: :rc:`legend.handleheight`
The height 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`.
draggable : bool, default: False
Whether the legend can be dragged with the mouse.
"""
_loc_doc_base = """
loc : str or pair of floats, default: {default}
The location of the legend.
The strings ``'upper left'``, ``'upper right'``, ``'lower left'``,
``'lower right'`` place the legend at the corresponding corner of the
{parent}.
The strings ``'upper center'``, ``'lower center'``, ``'center left'``,
``'center right'`` place the legend at the center of the corresponding edge
of the {parent}.
The string ``'center'`` places the legend at the center of the {parent}.
{best}
The location can also be a 2-tuple giving the coordinates of the lower-left
corner of the legend in {parent} 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" location can also be given as a
numeric value:
================== =============
Location String Location Code
================== =============
'best' (Axes only) 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
================== =============
{outside}"""
_loc_doc_best = """
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.
"""
_legend_kw_axes_st = (
_loc_doc_base.format(parent='axes', default=':rc:`legend.loc`',
best=_loc_doc_best, outside='') +
_legend_kw_doc_base)
_docstring.interpd.update(_legend_kw_axes=_legend_kw_axes_st)
_outside_doc = """
If a figure is using the constrained layout manager, the string codes
of the *loc* keyword argument can get better layout behaviour using the
prefix 'outside'. There is ambiguity at the corners, so 'outside
upper right' will make space for the legend above the rest of the
axes in the layout, and 'outside right upper' will make space on the
right side of the layout. In addition to the values of *loc*
listed above, we have 'outside right upper', 'outside right lower',
'outside left upper', and 'outside left lower'. See
:ref:`legend_guide` for more details.
"""
_legend_kw_figure_st = (
_loc_doc_base.format(parent='figure', default="'upper right'",
best='', outside=_outside_doc) +
_legend_kw_doc_base)
_docstring.interpd.update(_legend_kw_figure=_legend_kw_figure_st)
_legend_kw_both_st = (
_loc_doc_base.format(parent='axes/figure',
default=":rc:`legend.loc` for Axes, 'upper right' for Figure",
best=_loc_doc_best, outside=_outside_doc) +
_legend_kw_doc_base)
_docstring.interpd.update(_legend_kw_doc=_legend_kw_both_st)
_legend_kw_set_loc_st = (
_loc_doc_base.format(parent='axes/figure',
default=":rc:`legend.loc` for Axes, 'upper right' for Figure",
best=_loc_doc_best, outside=_outside_doc))
_docstring.interpd.update(_legend_kw_set_loc_doc=_legend_kw_set_loc_st)
class Legend(Artist):
"""
Place a legend on the figure/axes.
"""
# '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
reverse=False, # reverse 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
ncols=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
alignment="center", # control the alignment within the legend box
ncol=1, # synonym for ncols (backward compatibility)
draggable=False # whether the legend can be dragged with the mouse
):
"""
Parameters
----------
parent : `~matplotlib.axes.Axes` or `.Figure`
The artist that contains the legend.
handles : list of (`.Artist` or tuple 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 length of the shorter list.
Other Parameters
----------------
%(_legend_kw_doc)s
Attributes
----------
legend_handles
List of `.Artist` objects added as legend entries.
.. versionadded:: 3.7
"""
# local import only to avoid circularity
from matplotlib.axes import Axes
from matplotlib.figure import FigureBase
super().__init__()
if prop is None:
self.prop = FontProperties(size=mpl._val_or_rc(fontsize, "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.legend_handles = []
self._legend_title_box = None
#: A dictionary with the extra handler mappings for this Legend
#: instance.
self._custom_handler_map = handler_map
self.numpoints = mpl._val_or_rc(numpoints, 'legend.numpoints')
self.markerscale = mpl._val_or_rc(markerscale, 'legend.markerscale')
self.scatterpoints = mpl._val_or_rc(scatterpoints, 'legend.scatterpoints')
self.borderpad = mpl._val_or_rc(borderpad, 'legend.borderpad')
self.labelspacing = mpl._val_or_rc(labelspacing, 'legend.labelspacing')
self.handlelength = mpl._val_or_rc(handlelength, 'legend.handlelength')
self.handleheight = mpl._val_or_rc(handleheight, 'legend.handleheight')
self.handletextpad = mpl._val_or_rc(handletextpad, 'legend.handletextpad')
self.borderaxespad = mpl._val_or_rc(borderaxespad, 'legend.borderaxespad')
self.columnspacing = mpl._val_or_rc(columnspacing, 'legend.columnspacing')
self.shadow = mpl._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_deprecated("3.8", message=(
"An artist whose label starts with an underscore was passed to "
"legend(); such artists will no longer be ignored in the future. "
"To suppress this warning, explicitly filter out such artists, "
"e.g. with `[art for art in artists if not "
"art.get_label().startswith('_')]`."))
else:
_lab.append(label)
_hand.append(handle)
labels, handles = _lab, _hand
if reverse:
labels.reverse()
handles.reverse()
if len(handles) < 2:
ncols = 1
self._ncols = ncols if ncols != 1 else 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._mode = mode
self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)
# Figure out if self.shadow is valid
# If shadow was None, rcParams loads False
# So it shouldn't be None here
self._shadow_props = {'ox': 2, 'oy': -2} # default location offsets
if isinstance(self.shadow, dict):
self._shadow_props.update(self.shadow)
self.shadow = True
elif self.shadow in (0, 1, True, False):
self.shadow = bool(self.shadow)
else:
raise ValueError(
'Legend shadow must be a dict or bool, not '
f'{self.shadow!r} of type {type(self.shadow)}.'
)
# We use FancyBboxPatch to draw a legend frame. The location
# and size of the box will be updated during the drawing time.
facecolor = mpl._val_or_rc(facecolor, "legend.facecolor")
if facecolor == 'inherit':
facecolor = mpl.rcParams["axes.facecolor"]
edgecolor = mpl._val_or_rc(edgecolor, "legend.edgecolor")
if edgecolor == 'inherit':
edgecolor = mpl.rcParams["axes.edgecolor"]
fancybox = mpl._val_or_rc(fancybox, "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=mpl._val_or_rc(frameon, "legend.frameon")
)
self._set_artist_props(self.legendPatch)
_api.check_in_list(["center", "left", "right"], alignment=alignment)
self._alignment = alignment
# init with null renderer
self._init_legend_box(handles, labels, markerfirst)
# Set legend location
self.set_loc(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
self.set_draggable(state=draggable)
# 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'],
}
labelcolor = mpl._val_or_rc(labelcolor, 'legend.labelcolor')
if labelcolor is None:
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.legend_handles, self.texts):
try:
if handle.get_array() is not None:
continue
except AttributeError:
pass
for getter_name in getter_names:
try:
color = getattr(handle, getter_name)()
if isinstance(color, np.ndarray):
if (
color.shape[0] == 1
or np.isclose(color, color[0]).all()
):
text.set_color(color[0])
else:
pass
else:
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}")
legendHandles = _api.deprecated('3.7', alternative="legend_handles")(
property(lambda self: self.legend_handles))
def _set_artist_props(self, a):
"""
Set the boilerplate props for artists added to axes.
"""
a.set_figure(self.figure)
if self.isaxes:
a.axes = self.axes
a.set_transform(self.get_transform())
@_docstring.dedent_interpd
def set_loc(self, loc=None):
"""
Set the location of the legend.
.. versionadded:: 3.8
Parameters
----------
%(_legend_kw_set_loc_doc)s
"""
loc0 = loc
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'
type_err_message = ("loc must be string, coordinate tuple, or"
f" an integer 0-10, not {loc!r}")
# handle outside legends:
self._outside_loc = None
if isinstance(loc, str):
if loc.split()[0] == 'outside':
# strip outside:
loc = loc.split('outside ')[1]
# strip "center" at the beginning
self._outside_loc = loc.replace('center ', '')
# strip first
self._outside_loc = self._outside_loc.split()[0]
locs = loc.split()
if len(locs) > 1 and locs[0] in ('right', 'left'):
# locs doesn't accept "left upper", etc, so swap
if locs[0] != 'center':
locs = locs[::-1]
loc = locs[0] + ' ' + locs[1]
# check that loc is in acceptable strings
loc = _api.check_getitem(self.codes, loc=loc)
elif np.iterable(loc):
# coerce iterable into tuple
loc = tuple(loc)
# validate the tuple represents Real coordinates
if len(loc) != 2 or not all(isinstance(e, numbers.Real) for e in loc):
raise ValueError(type_err_message)
elif isinstance(loc, int):
# validate the integer represents a string numeric value
if loc < 0 or loc > 10:
raise ValueError(type_err_message)
else:
# all other cases are invalid values of loc
raise ValueError(type_err_message)
if self.isaxes and self._outside_loc:
raise ValueError(
f"'outside' option for loc='{loc0}' keyword argument only "
"works for figure legends")
if not self.isaxes and loc == 0:
raise ValueError(
"Automatic legend placement (loc='best') not implemented for "
"figure legend")
tmp = self._loc_used_default
self._set_loc(loc)
self._loc_used_default = tmp # ignore changes done by _set_loc
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 set_ncols(self, ncols):
"""Set the number of columns."""
self._ncols = ncols
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)
# self.shadow is validated in __init__
# So by here it is a bool and self._shadow_props contains any configs
if self.shadow:
Shadow(self.legendPatch, **self._shadow_props).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 "
f"{type(orig_handle).__name__} "
"instances.\nA proxy artist may be used "
"instead.\nSee: https://matplotlib.org/"
"stable/users/explain/axes/legend_guide.html"
"#controlling-the-legend-entries")
# 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 ncols columns, with the
# first n%ncols columns having an extra entry. filter(len, ...)
# handles the case where n < ncols: the last ncols-n columns are empty
# and get filtered out.
for handles_and_labels_column in filter(
len, np.array_split(handles_and_labels, self._ncols)):
# 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=self._alignment,
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.legend_handles = 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):
lines.append(
artist.get_transform().transform_path(artist.get_path()))
elif isinstance(artist, Collection):
transform, transOffset, hoffsets, _ = artist._prepare_points()
if len(hoffsets):
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.legend_handles if isinstance(h, Line2D)]