将图例添加到嵌套饼图

Question

我想在嵌套饼图图的内部饼图中添加一个图例：

import matplotlib.pyplot as plt

# Make data: I have 3 groups and 7 subgroups
group_names=['groupA', 'groupB', 'groupC']
group_size=[12,11,30]
subgroup_names=['A.1', 'A.2', 'A.3', 'B.1', 'B.2', 'C.1', 'C.2', 'C.3', 
'C.4', 'C.5']
subgroup_size=[4,3,5,6,5,10,5,5,4,6]

# Create colors
a, b, c=[plt.cm.Blues, plt.cm.Reds, plt.cm.Greens]

# First Ring (outside)
fig, ax = plt.subplots()
ax.axis('equal')
mypie, _ = ax.pie(group_size, radius=1.3, labels=group_names, colors= 
[a(0.6), b(0.6), c(0.6)] )
plt.setp( mypie, width=0.3, edgecolor='white')

# Second Ring (Inside)
mypie2, _ = ax.pie(subgroup_size, radius=1.3-0.3, 
labels=subgroup_names, labeldistance=0.7, colors=[a(0.5), a(0.4), 
a(0.3), b(0.5), b(0.4), c(0.6), c(0.5), c(0.4), c(0.3), c(0.2)])
plt.setp( mypie2, width=0.4, edgecolor='white')
plt.margins(0,0)

subgroup_names_legs=['A.1:a1desc', 'A.2:a2desc', 'A.3:a3desc', 
'B.1:b1desc', 'B.2:b2desc', 'C.1:c1desc', 'C.2:c2desc', 'C.3:c3desc', 
'C.4:c4desc', 'C.5:c5desc']
plt.legend(subgroup_names_legs,loc='best')

# show it
plt.show()

所以我得到了这个结果：

我想在图例中正确引用颜色（例如，A1，A2和A3是不同种类的蓝色等）

另外，如何以不与图表重叠的方式显示图例？

Answer 1

问题是，首先你使用labels=subgroup_names分配图例，然后使用plt.legend(subgroup_names_legs,loc='best')重新分配它们。因此，您将覆盖现有值，从而破坏顺序。这就是您看到无与伦比的颜色的原因。

要避免图例框与图形重叠，可以将其位置指定为loc=(0.9, 0.1)

要从外部饼图中删除图例，您可以获取图例句柄和标签，然后排除前三个单元格，这样您就只能获得内部饼图的图例

# First Ring (outside)
fig, ax = plt.subplots()
ax.axis('equal')
mypie, _ = ax.pie(group_size, radius=1.3, labels=group_names, colors= 
[a(0.6), b(0.6), c(0.6)] )
plt.setp( mypie, width=0.3, edgecolor='white')

# Second Ring (Inside)
mypie2, _ = ax.pie(subgroup_size, radius=1.3-0.3, 
labels=subgroup_names, labeldistance=0.7, colors=[a(0.5), a(0.4), 
a(0.3), b(0.5), b(0.4), c(0.6), c(0.5), c(0.4), c(0.3), c(0.2)])
plt.setp( mypie2, width=0.4, edgecolor='white')
plt.margins(0,0)

plt.legend(loc=(0.9, 0.1))
handles, labels = ax.get_legend_handles_labels()

ax.legend(handles[3:], subgroup_names_legs, loc=(0.9, 0.1))
plt.show()