[英]Adding a legend to a matplotlib boxplot with multiple plots on same axes
I have a boxplot generated with matplotlib:我有一个用 matplotlib 生成的箱线图:
However, I have no idea how to generate the legend.但是,我不知道如何生成图例。 Whenever I try the following I get an error saying
Legend does not support {boxes: ...
I've done a fair bit of searching and there doesn't seem to be an example showing how to achieve this.每当我尝试以下操作时,我都会收到一条错误消息,指出
Legend does not support {boxes: ...
我已经进行了大量搜索,但似乎没有示例说明如何实现这一点。 Any help would be appreciated!任何帮助,将不胜感激!
bp1 = ax.boxplot(data1, positions=[1,4], notch=True, widths=0.35, patch_artist=True)
bp2 = ax.boxplot(data2, positions=[2,5], notch=True, widths=0.35, patch_artist=True)
ax.legend([bp1, bp2], ['A', 'B'], loc='upper right')
The boxplot
returns a dictionary of artists boxplot
返回艺术家字典
result : dict
结果:字典
A dictionary mapping each component of the boxplot to a list of the matplotlib.lines.Line2D instances created.将箱线图的每个组件映射到创建的 matplotlib.lines.Line2D 实例列表的字典。 That dictionary has the following keys (assuming vertical boxplots):
该字典具有以下键(假设为垂直箱线图):
boxes
: the main body of the boxplot showing the quartiles and the median's confidence intervals if enabled.boxes
:箱线图的主体,显示四分位数和中位数的置信区间(如果启用)。- [...]
[...]
Using the boxes
, you can get the legend artists as使用这些
boxes
,您可以将传奇艺术家作为
ax.legend([bp1["boxes"][0], bp2["boxes"][0]], ['A', 'B'], loc='upper right')
Complete example:完整示例:
import matplotlib.pyplot as plt
import numpy as np; np.random.seed(1)
data1=np.random.randn(40,2)
data2=np.random.randn(30,2)
fig, ax = plt.subplots()
bp1 = ax.boxplot(data1, positions=[1,4], notch=True, widths=0.35,
patch_artist=True, boxprops=dict(facecolor="C0"))
bp2 = ax.boxplot(data2, positions=[2,5], notch=True, widths=0.35,
patch_artist=True, boxprops=dict(facecolor="C2"))
ax.legend([bp1["boxes"][0], bp2["boxes"][0]], ['A', 'B'], loc='upper right')
ax.set_xlim(0,6)
plt.show()
Just as a complement to @ImportanceOfBeingErnest's response, if you are plotting in a for loop like this:作为对@ImportanceOfBeingErnest 响应的补充,如果您在这样的 for 循环中绘图:
for data in datas:
ax.boxplot(data, positions=[1,4], notch=True, widths=0.35,
patch_artist=True, boxprops=dict(facecolor="C0"))
You cannot save the plots as variables.您不能将图保存为变量。 So in that case, create legend labels list
legends
, append the plots into another list elements
and use list comprehension to put a legend for each of them:因此,在这种情况下,创建图例标签列表
legends
,将图附加到另一个列表elements
并使用列表理解为每个elements
放置一个图例:
labels = ['A', 'B']
colors = ['blue', 'red']
elements = []
for dIdx, data in enumerate(datas):
elements.append(ax.boxplot(data, positions=[1,4], notch=True,\
widths=0.35, patch_artist=True, boxprops=dict(facecolor=colors[dIdx])))
ax.legend([element["boxes"][0] for element in elements],
[labels[idx] for idx,_ in enumerate(datas)])
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