如何在matplotlib中的子图下面添加图例? [英] How to add legend below subplots in matplotlib?

问题描述

我正在尝试在3列子图图形下添加图例.

I am trying to add a legend below a 3-column subplot figure.

我尝试了以下操作:

fig, ax = plt.subplots(ncols=3)
ax[0].plot(data1)
ax[1].plot(data2)
ax[2].plot(data3)

ax_sub = plt.subplot(111)
box = ax_sub.get_position()
ax_sub.set_position([box.x0, box.y0 + box.height * 0.1,box.width, box.height * 0.9])
ax_sub.legend(['A', 'B', 'C'],loc='upper center', bbox_to_anchor=(0.5, -0.3),fancybox=False, shadow=False, ncol=3)
plt.show()

但是，这只会创建一个空框架.当我注释掉ax_sub部分时，我的子图显示很好(但没有图例...)...

However, this creates just one empty frame. When I comment out the ax_sub part, my subplots show up nice (but without a legend...)...

非常感谢！

这与如何将图例删除有关的情节

推荐答案

图例需要知道其应显示的内容.默认情况下，它将从创建艺术家的轴中获取带标签的艺术家.由于此处的轴ax_sub为空，因此图例也将为空.

The legend needs to know what it should show. By default it will take the labeled artist from the axes it is created in. Since here the axes ax_sub is empty, the legend will be empty as well.

使用ax_sub可能没有任何意义.我们可以改用中轴(ax[1])放置图例.但是，我们仍然需要所有应该出现在图例中的艺术家.对于行来说，这很容易；可以提供一行行作为handles参数的句柄.

The use of the ax_sub may anyways not make too much sense. We could instead use the middle axes (ax[1]) to place the legend. However, we still need all artists that should appear in the legend. For lines this is easy; one would supply a list of lines as handles to the handles argument.

import matplotlib.pyplot as plt
import numpy as np

data1,data2,data3 = np.random.randn(3,12)

fig, ax = plt.subplots(ncols=3)
l1, = ax[0].plot(data1)
l2, = ax[1].plot(data2)
l3, = ax[2].plot(data3)

fig.subplots_adjust(bottom=0.3, wspace=0.33)

ax[1].legend(handles = [l1,l2,l3] , labels=['A', 'B', 'C'],loc='upper center', 
             bbox_to_anchor=(0.5, -0.2),fancybox=False, shadow=False, ncol=3)
plt.show()

这篇关于如何在matplotlib中的子图下面添加图例?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！