Python Matplotlib多色图例条目
Mat*_*kes 8 python matplotlib legend
我想在matplotlib中创建一个传奇条目,如下所示:
它具有给定图例项目的多种颜色.代码如下所示,输出一个红色矩形.我想知道我需要做什么来覆盖另一种颜色？或者有更好的解决方案吗？
import matplotlib.patches as mpatches
import matplotlib.pyplot as plt
red_patch = mpatches.Patch(color='red', label='Foo')
plt.legend(handles=[red_patch])
plt.show()
事实上，有一种正确的方法可以通过实现自定义图例处理程序来实现此目的，如 matplotlib-doc 中“实现自定义图例处理程序” （此处）下所述：
import matplotlib.pyplot as plt
from matplotlib.collections import PatchCollection
# define an object that will be used by the legend
class MulticolorPatch(object):
def __init__(self, colors):
self.colors = colors
# define a handler for the MulticolorPatch object
class MulticolorPatchHandler(object):
def legend_artist(self, legend, orig_handle, fontsize, handlebox):
width, height = handlebox.width, handlebox.height
patches = []
for i, c in enumerate(orig_handle.colors):
patches.append(plt.Rectangle([width/len(orig_handle.colors) * i - handlebox.xdescent,
-handlebox.ydescent],
width / len(orig_handle.colors),
height,
facecolor=c,
edgecolor='none'))
patch = PatchCollection(patches,match_original=True)
handlebox.add_artist(patch)
return patch
# ------ choose some colors
colors1 = ['g', 'b', 'c', 'm', 'y']
colors2 = ['k', 'r', 'k', 'r', 'k', 'r']
# ------ create a dummy-plot (just to show that it works)
f, ax = plt.subplots()
ax.plot([1,2,3,4,5], [1,4.5,2,5.5,3], c='g', lw=0.5, ls='--',
label='... just a line')
ax.scatter(range(len(colors1)), range(len(colors1)), c=colors1)
ax.scatter([range(len(colors2))], [.5]*len(colors2), c=colors2, s=50)
# ------ get the legend-entries that are already attached to the axis
h, l = ax.get_legend_handles_labels()
# ------ append the multicolor legend patches
h.append(MulticolorPatch(colors1))
l.append("a nice multicolor legend patch")
h.append(MulticolorPatch(colors2))
l.append("and another one")
# ------ create the legend
f.legend(h, l, loc='upper left',
handler_map={MulticolorPatch: MulticolorPatchHandler()},
bbox_to_anchor=(.125,.875))
我提出的解决方案是将两个不同的代理艺术家组合为一个条目图例，如下所述：为图例组合两个 Pyplot 补丁。
然后策略是fillstyle将第一个正方形标记的设置为，left而另一个设置为right（参见http://matplotlib.org/1.3.0/examples/pylab_examples/filledmarker_demo.html）。然后可以将两种不同的颜色归因于每个标记，以生成所需的双色图例条目。
下面的代码显示了如何做到这一点。请注意，numpoints=1参数 inplt.legend很重要，以便为每个条目仅显示一个标记。
import matplotlib.pyplot as plt
plt.close('all')
#---- Generate a Figure ----
fig = plt.figure(figsize=(4, 4))
ax = fig.add_axes([0.15, 0.15, 0.75, 0.75])
ax.axis([0, 1, 0, 1])
#---- Define First Legend Entry ----
m1, = ax.plot([], [], c='red' , marker='s', markersize=20,
fillstyle='left', linestyle='none')
m2, = ax.plot([], [], c='blue' , marker='s', markersize=20,
fillstyle='right', linestyle='none')
#---- Define Second Legend Entry ----
m3, = ax.plot([], [], c='cyan' , marker='s', markersize=20,
fillstyle='left', linestyle='none')
m4, = ax.plot([], [], c='magenta' , marker='s', markersize=20,
fillstyle='right', linestyle='none')
#---- Plot Legend ----
ax.legend(((m2, m1), (m3, m4)), ('Foo', 'Foo2'), numpoints=1, labelspacing=2,
loc='center', fontsize=16)
plt.show(block=False)
结果是：
免责声明：这仅适用于双色图例条目。如果需要两种以上的颜色，除了@jwinterm（Python Matplotlib Multi-color Legend Entry） 描述的方法之外，我想不出任何其他方法来做到这一点
小智 5
也许是另一个处理两个以上补丁的技巧。确保根据列数对句柄/标签进行排序：
from matplotlib.patches import Patch
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
pa1 = Patch(facecolor='red', edgecolor='black')
pa2 = Patch(facecolor='blue', edgecolor='black')
pa3 = Patch(facecolor='green', edgecolor='black')
#
pb1 = Patch(facecolor='pink', edgecolor='black')
pb2 = Patch(facecolor='orange', edgecolor='black')
pb3 = Patch(facecolor='purple', edgecolor='black')
ax.legend(handles=[pa1, pb1, pa2, pb2, pa3, pb3],
labels=['', '', '', '', 'First', 'Second'],
ncol=3, handletextpad=0.5, handlelength=1.0, columnspacing=-0.5,
loc='center', fontsize=16)
plt.show()
结果是：
我非常喜欢@raphael 的回答。这是带有圆圈的版本。此外，我对代码进行了一些重构和修剪，使其更加模块化。
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors
class MulticolorCircles:
"""
For different shapes, override the ``get_patch`` method, and add the new
class to the handler map, e.g. via
ax_r.legend(ax_r_handles, ax_r_labels, handlelength=CONF.LEGEND_ICON_SIZE,
borderpad=1.2, labelspacing=1.2,
handler_map={MulticolorCircles: MulticolorHandler})
"""
def __init__(self, face_colors, edge_colors=None, face_alpha=1,
radius_factor=1):
"""
"""
assert 0 <= face_alpha <= 1, f"Invalid face_alpha: {face_alpha}"
assert radius_factor > 0, "radius_factor must be positive"
self.rad_factor = radius_factor
self.fc = [mcolors.colorConverter.to_rgba(fc, alpha=face_alpha)
for fc in face_colors]
self.ec = edge_colors
if edge_colors is None:
self.ec = ["none" for _ in self.fc]
self.N = len(self.fc)
def get_patch(self, width, height, idx, fc, ec):
"""
"""
w_chunk = width / self.N
radius = min(w_chunk / 2, height) * self.rad_factor
xy = (w_chunk * idx + radius, radius)
patch = plt.Circle(xy, radius, facecolor=fc, edgecolor=ec)
return patch
def __call__(self, width, height):
"""
"""
patches = []
for i, (fc, ec) in enumerate(zip(self.fc, self.ec)):
patch = self.get_patch(width, height, i, fc, ec)
patches.append(patch)
result = PatchCollection(patches, match_original=True)
#
return result
class MulticolorHandler:
"""
"""
@staticmethod
def legend_artist(legend, orig_handle, fontsize, handlebox):
"""
"""
width, height = handlebox.width, handlebox.height
patch = orig_handle(width, height)
handlebox.add_artist(patch)
return patch
示例用法和图像，请注意，某些图例手柄具有radius_factor=0.5，因为真实尺寸太小。
ax_handles, ax_labels = ax.get_legend_handles_labels()
ax_labels.append(AUDIOSET_LABEL)
ax_handles.append(MulticolorCircles([AUDIOSET_COLOR],
face_alpha=LEGEND_SHADOW_ALPHA))
ax_labels.append(FRAUNHOFER_LABEL)
ax_handles.append(MulticolorCircles([FRAUNHOFER_COLOR],
face_alpha=LEGEND_SHADOW_ALPHA))
ax_labels.append(TRAIN_SOURCE_NORMAL_LABEL)
ax_handles.append(MulticolorCircles(SHADOW_COLORS["source"],
face_alpha=LEGEND_SHADOW_ALPHA))
ax_labels.append(TRAIN_TARGET_NORMAL_LABEL)
ax_handles.append(MulticolorCircles(SHADOW_COLORS["target"],
face_alpha=LEGEND_SHADOW_ALPHA))
ax_labels.append(TEST_SOURCE_ANOMALY_LABEL)
ax_handles.append(MulticolorCircles(DOT_COLORS["anomaly_source"],
radius_factor=LEGEND_DOT_RATIO))
ax_labels.append(TEST_TARGET_ANOMALY_LABEL)
ax_handles.append(MulticolorCircles(DOT_COLORS["anomaly_target"],
radius_factor=LEGEND_DOT_RATIO))
#
ax.legend(ax_handles, ax_labels, handlelength=LEGEND_ICON_SIZE,
borderpad=1.1, labelspacing=1.1,
handler_map={MulticolorCircles: MulticolorHandler})
