如何避免Matplotlib绘制的饼图与图例重叠

问题说明 #

使用Matplotlib绘制饼图时，图例与饼图区域出现重叠，影响可视化效果。原代码及重叠效果如下：

原代码 #

import matplotlib.pyplot as plt
import numpy as np
y = np.array([1,117,11,5])
mylabels = "Complete","Pass","Fail","Block"
mycolors = ["b","g","r","c"]
myexplode =[0.6,0,0.4,0]
plt.pie(y,labels=mylabels,explode = myexplode,shadow=True,colors = mycolors,autopct ='%1.1f%%')
plt.legend(title ="Test result types")
plt.show()

重叠效果 #

解决办法 #

方法1：指定图例位置与偏移 #

通过plt.legend()的loc参数设置图例位置，配合bbox_to_anchor调整偏移量，将图例移至饼图外侧：

import matplotlib.pyplot as plt
import numpy as np
y = np.array([1,117,11,5])
mylabels = "Complete","Pass","Fail","Block"
mycolors = ["b","g","r","c"]
myexplode =[0.6,0,0.4,0]
plt.pie(y,labels=mylabels,explode = myexplode,shadow=True,colors = mycolors,autopct ='%1.1f%%')
# 将图例放在饼图右侧，通过bbox_to_anchor调整位置避免重叠
plt.legend(title ="Test result types", loc="upper right", bbox_to_anchor=(1.3, 1))
plt.show()

方法2：自动调整布局 #

使用plt.tight_layout()让Matplotlib自动调整元素间距，也可提前设置画布尺寸预留空间：

import matplotlib.pyplot as plt
import numpy as np
# 设置合适的画布尺寸
fig, ax = plt.subplots(figsize=(8, 6))
y = np.array([1,117,11,5])
mylabels = "Complete","Pass","Fail","Block"
mycolors = ["b","g","r","c"]
myexplode =[0.6,0,0.4,0]
ax.pie(y,labels=mylabels,explode = myexplode,shadow=True,colors = mycolors,autopct ='%1.1f%%')
ax.legend(title ="Test result types")
# 自动调整布局，避免元素重叠
plt.tight_layout()
plt.show()

方法3：仅保留图例展示标签 #

若饼图自带标签与图例重复，可去掉饼图的labels参数，仅通过图例展示分类：

import matplotlib.pyplot as plt
import numpy as np
y = np.array([1,117,11,5])
mylabels = ["Complete","Pass","Fail","Block"]
mycolors = ["b","g","r","c"]
myexplode =[0.6,0,0.4,0]
# 不显示饼图自带标签
plt.pie(y,explode = myexplode,shadow=True,colors = mycolors,autopct ='%1.1f%%')
# 图例传入自定义标签并调整位置
plt.legend(title ="Test result types", labels=mylabels, loc="upper right", bbox_to_anchor=(1.3, 1))
plt.show()

内容的提问来源于stack exchange，提问作者PChao