"""
Place a legend on the axes at location loc. Labels are a
sequence of strings and loc can be a string or an integer
specifying the legend location
The location codes are
'best' : 0, (only implemented for axis 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,
Return value is a sequence of text, line instances that make
up the legend
"""
from __future__ import division
import warnings
import numpy as npy
from matplotlib import rcParams
from artist import Artist
from cbook import is_string_like, iterable, silent_list
from font_manager import FontProperties
from lines import Line2D
from mlab import segments_intersect
from patches import Patch, Rectangle, Shadow, bbox_artist
from collections import LineCollection, RegularPolyCollection
from text import Text
from transforms import Affine2D, Bbox, BboxTransformTo
class Legend(Artist):
"""
Place a legend on the axes at location loc. Labels are a
sequence of strings and loc can be a string or an integer
specifying the legend location
The location codes are
'best' : 0, (only implemented for axis 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,
Return value is a sequence of text, line instances that make
up the legend
"""
codes = {'best' : 0, # only implemented for axis 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"
def __init__(self, parent, handles, labels,
loc = None,
numpoints = None, # the number of points in the legend line
prop = None,
pad = None, # the fractional whitespace inside the legend border
markerscale = None, # the relative size of legend markers vs. original
# the following dimensions are in axes coords
labelsep = None, # the vertical space between the legend entries
handlelen = None, # the length of the legend lines
handletextsep = None, # the space between the legend line and legend text
axespad = None, # the border between the axes and legend edge
shadow = None
):
"""
parent # the artist that contains the legend
handles # a list of artists (lines, patches) to add to the legend
labels # a list of strings to label the legend
loc # a location code
numpoints = 4 # the number of points in the legend line
prop = FontProperties(size='smaller') # the font property
pad = 0.2 # the fractional whitespace inside the legend border
markerscale = 0.6 # the relative size of legend markers vs. original
shadow # if True, draw a shadow behind legend
The following dimensions are in axes coords
labelsep = 0.005 # the vertical space between the legend entries
handlelen = 0.05 # the length of the legend lines
handletextsep = 0.02 # the space between the legend line and legend text
axespad = 0.02 # the border between the axes and legend edge
"""
from axes import Axes # local import only to avoid circularity
from figure import Figure # local import only to avoid circularity
Artist.__init__(self)
proplist=[numpoints, pad, markerscale, labelsep, handlelen, handletextsep, axespad, shadow]
propnames=['numpoints', 'pad', 'markerscale', 'labelsep', 'handlelen', 'handletextsep', 'axespad', 'shadow']
for name, value in zip(propnames,proplist):
if value is None:
value=rcParams["legend."+name]
setattr(self,name,value)
if prop is None:
self.prop=FontProperties(size=rcParams["legend.fontsize"])
else:
self.prop=prop
self.fontsize = self.prop.get_size_in_points()
if isinstance(parent,Axes):
self.isaxes = True
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._offsetTransform = Affine2D()
self._parentTransform = BboxTransformTo(parent.bbox)
Artist.set_transform(self, self._offsetTransform + self._parentTransform)
if loc is None:
loc = rcParams["legend.loc"]
if not self.isaxes and loc in [0,'best']:
loc = 'upper right'
if is_string_like(loc):
if not self.codes.has_key(loc):
if self.isaxes:
warnings.warn('Unrecognized location "%s". Falling back on "best"; '
'valid locations are\n\t%s\n'
% (loc, '\n\t'.join(self.codes.keys())))
loc = 0
else:
warnings.warn('Unrecognized location "%s". Falling back on "upper right"; '
'valid locations are\n\t%s\n'
% (loc, '\n\t'.join(self.codes.keys())))
loc = 1
else:
loc = self.codes[loc]
if not self.isaxes and loc == 0:
warnings.warn('Automatic legend placement (loc="best") not implemented for figure legend. '
'Falling back on "upper right".')
loc = 1
self._loc = loc
self.legendPatch = Rectangle(
xy=(0.0, 0.0), width=0.5, height=0.5,
facecolor='w', edgecolor='k',
)
self._set_artist_props(self.legendPatch)
# make a trial box in the middle of the axes. relocate it
# based on it's bbox
left, top = 0.5, 0.5
if self.numpoints == 1:
self._xdata = npy.array([left + self.handlelen*0.5])
else:
self._xdata = npy.linspace(left, left + self.handlelen, self.numpoints)
textleft = left+ self.handlelen+self.handletextsep
self.texts = self._get_texts(labels, textleft, top)
self.legendHandles = self._get_handles(handles, self.texts)
self._drawFrame = True
def _set_artist_props(self, a):
a.set_figure(self.figure)
a.set_transform(self.get_transform())
def _approx_text_height(self):
return self.fontsize/72.0*self.figure.dpi/self.parent.bbox.height
def draw(self, renderer):
if not self.get_visible(): return
renderer.open_group('legend')
self._update_positions(renderer)
if self._drawFrame:
if self.shadow:
shadow = Shadow(self.legendPatch, -0.005, -0.005)
shadow.draw(renderer)
self.legendPatch.draw(renderer)
if not len(self.legendHandles) and not len(self.texts): return
for h in self.legendHandles:
if h is not None:
h.draw(renderer)
if 0: bbox_artist(h, renderer)
for t in self.texts:
if 0: bbox_artist(t, renderer)
t.draw(renderer)
renderer.close_group('legend')
#draw_bbox(self.save, renderer, 'g')
#draw_bbox(self.ibox, renderer, 'r', self.get_transform())
def _get_handle_text_bbox(self, renderer):
'Get a bbox for the text and lines in axes coords'
bboxesText = [t.get_window_extent(renderer) for t in self.texts]
bboxesHandles = [h.get_window_extent(renderer) for h in self.legendHandles if h is not None]
bboxesAll = bboxesText
bboxesAll.extend(bboxesHandles)
bbox = Bbox.union(bboxesAll)
self.save = bbox
ibox = bbox.inverse_transformed(self.get_transform())
self.ibox = ibox
return ibox
def _get_handles(self, handles, texts):
HEIGHT = self._approx_text_height()
ret = [] # the returned legend lines
for handle, label in zip(handles, texts):
x, y = label.get_position()
x -= self.handlelen + self.handletextsep
if isinstance(handle, Line2D):
ydata = (y-HEIGHT/2)*npy.ones(self._xdata.shape, float)
legline = Line2D(self._xdata, ydata)
legline.update_from(handle)
self._set_artist_props(legline) # after update
legline.set_clip_box(None)
legline.set_clip_path(self.legendPatch)
legline.set_markersize(self.markerscale*legline.get_markersize())
ret.append(legline)
elif isinstance(handle, Patch):
p = Rectangle(xy=(min(self._xdata), y-3/4*HEIGHT),
width = self.handlelen, height=HEIGHT/2,
)
p.update_from(handle)
self._set_artist_props(p)
p.set_clip_box(None)
p.set_clip_path(self.legendPatch)
ret.append(p)
elif isinstance(handle, LineCollection):
ydata = (y-HEIGHT/2)*npy.ones(self._xdata.shape, float)
legline = Line2D(self._xdata, ydata)
self._set_artist_props(legline)
legline.set_clip_box(None)
legline.set_clip_path(self.legendPatch)
lw = handle.get_linewidth()[0]
dashes = handle.get_dashes()
color = handle.get_colors()[0]
legline.set_color(color)
legline.set_linewidth(lw)
legline.set_dashes(dashes)
ret.append(legline)
elif isinstance(handle, RegularPolyCollection):
p = Rectangle(xy=(min(self._xdata), y-3/4*HEIGHT),
width = self.handlelen, height=HEIGHT/2,
)
p.set_facecolor(handle._facecolors[0])
if handle._edgecolors != 'None':
p.set_edgecolor(handle._edgecolors[0])
self._set_artist_props(p)
p.set_clip_box(None)
p.set_clip_path(self.legendPatch)
ret.append(p)
else:
ret.append(None)
return ret
def _auto_legend_data(self):
""" Returns list of vertices and extents covered by the plot.
Returns a two long list.
First element is a list of (x, y) vertices (in
axes-coordinates) covered by all the lines and line
collections, in the legend's handles.
Second element is a list of bounding boxes for all the patches in
the legend's handles.
"""
assert self.isaxes # should always hold because function is only called internally
ax = self.parent
vertices = []
bboxes = []
lines = []
inverse_transform = ax.transAxes.inverted()
for handle in ax.lines:
assert isinstance(handle, Line2D)
path = handle.get_path()
trans = handle.get_transform()
tpath = trans.transform_path(path)
apath = inverse_transform.transform_path(tpath)
lines.append(apath)
for handle in ax.patches:
assert isinstance(handle, Patch)
if isinstance(handle, Rectangle):
transform = handle.get_data_transform() + inverse_transform
bboxes.append(handle.get_bbox().transformed(transform))
else:
transform = handle.get_transform() + inverse_transform
bboxes.append(handle.get_path().get_extents(transform))
return [vertices, bboxes, lines]
def draw_frame(self, b):
'b is a boolean. Set draw frame to b'
self._drawFrame = b
def get_frame(self):
'return the Rectangle instance used to frame the legend'
return self.legendPatch
def get_lines(self):
'return a list of lines.Line2D instances in the legend'
return [h for h in self.legendHandles if isinstance(h, Line2D)]
def get_patches(self):
'return a list of patch instances in the legend'
return silent_list('Patch', [h for h in self.legendHandles if isinstance(h, Patch)])
def get_texts(self):
'return a list of text.Text instance in the legend'
return silent_list('Text', self.texts)
def _get_texts(self, labels, left, upper):
# height in axes coords
HEIGHT = self._approx_text_height()
pos = upper
x = left
ret = [] # the returned list of text instances
for l in labels:
text = Text(
x=x, y=pos,
text=l,
fontproperties=self.prop,
verticalalignment='top',
horizontalalignment='left'
)
self._set_artist_props(text)
ret.append(text)
pos -= HEIGHT
return ret
def get_window_extent(self):
return self.legendPatch.get_window_extent()
def _offset(self, ox, oy):
'Move all the artists by ox,oy (axes coords)'
self._offsetTransform.clear().translate(ox, oy)
def _find_best_position(self, width, height, 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 axes coords.
"""
assert self.isaxes # should always hold because function is only called internally
verts, bboxes, lines = self._auto_legend_data()
consider = [self._loc_to_axes_coords(x, width, height) for x in range(1, len(self.codes))]
tx, ty = self.legendPatch.get_x(), self.legendPatch.get_y()
candidates = []
for l, b in consider:
legendBox = Bbox.from_bounds(l, b, width, height)
badness = 0
badness = legendBox.count_contains(verts)
badness += legendBox.count_overlaps(bboxes)
for line in lines:
if line.intersects_bbox(legendBox):
badness += 1
ox, oy = l-tx, b-ty
if badness == 0:
return ox, oy
candidates.append((badness, (ox, oy)))
# rather than use min() or list.sort(), do this so that we are assured
# that in the case of two equal badnesses, the one first considered is
# returned.
minCandidate = candidates[0]
for candidate in candidates:
if candidate[0] < minCandidate[0]:
minCandidate = candidate
ox, oy = minCandidate[1]
return ox, oy
def _loc_to_axes_coords(self, loc, width, height):
"""Convert a location code to axes coordinates.
- loc: a location code in range(1, 11).
This corresponds to the possible values for self._loc, excluding "best".
- width, height: the final size of the legend, axes units.
"""
assert loc in range(1,11) # called only internally
BEST, UR, UL, LL, LR, R, CL, CR, LC, UC, C = range(11)
if loc in (UL, LL, CL): # left
x = self.axespad
elif loc in (UR, LR, CR, R): # right
x = 1.0 - (width + self.axespad)
elif loc in (LC, UC, C): # center x
x = (0.5 - width/2.0)
if loc in (UR, UL, UC): # upper
y = 1.0 - (height + self.axespad)
elif loc in (LL, LR, LC): # lower
y = self.axespad
elif loc in (CL, CR, C, R): # center y
y = (0.5 - height/2.0)
return x,y
def _update_positions(self, renderer):
# called from renderer to allow more precise estimates of
# widths and heights with get_window_extent
if not len(self.legendHandles) and not len(self.texts): return
def get_tbounds(text): #get text bounds in axes coords
bbox = text.get_window_extent(renderer)
bboxa = bbox.inverse_transformed(self.get_transform())
return bboxa.bounds
hpos = []
for t, tabove in zip(self.texts[1:], self.texts[:-1]):
x,y = t.get_position()
l,b,w,h = get_tbounds(tabove)
b -= self.labelsep
h += 2*self.labelsep
hpos.append( (b,h) )
t.set_position( (x, b-0.1*h) )
# now do the same for last line
l,b,w,h = get_tbounds(self.texts[-1])
b -= self.labelsep
h += 2*self.labelsep
hpos.append( (b,h) )
for handle, tup in zip(self.legendHandles, hpos):
y,h = tup
if isinstance(handle, Line2D):
ydata = y*npy.ones(self._xdata.shape, float)
handle.set_ydata(ydata+h/2)
elif isinstance(handle, Rectangle):
handle.set_y(y+1/4*h)
handle.set_height(h/2)
# Set the data for the legend patch
bbox = self._get_handle_text_bbox(renderer)
bbox = bbox.expanded(1 + self.pad, 1 + self.pad)
l, b, w, h = bbox.bounds
self.legendPatch.set_bounds(l, b, w, h)
ox, oy = 0, 0 # center
if iterable(self._loc) and len(self._loc)==2:
xo = self.legendPatch.get_x()
yo = self.legendPatch.get_y()
x, y = self._loc
ox, oy = x-xo, y-yo
elif self._loc == 0: # "best"
ox, oy = self._find_best_position(w, h)
else:
x, y = self._loc_to_axes_coords(self._loc, w, h)
ox, oy = x-l, y-b
self._offset(ox, oy)
#artist.kwdocd['Legend'] = kwdoc(Legend)
