python matplotlib实现将图例放在图外
时间：2021-04-26 11:03:36|栏目：Python代码|点击： 次
关于matplotlib如何设置图例的位置？如何将图例放在图外？以及如何在一幅图有多个子图的情况下，删除重复的图例？我用一个简单的例子说明一下。
import pandas as pd import numpy as np import matplotlib.pyplot as plt fig = plt.figure(1) ax1 = fig.add_subplot(2,2,1) ax2 = fig.add_subplot(2,2,2) ax3 = fig.add_subplot(2,2,3) ax4 = fig.add_subplot(2,2,4) df1 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df2 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df3 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df4 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df1.plot(ax = ax1, title = "df1", grid = 'on') df2.plot(ax = ax2, title = "df1", grid = 'on') df3.plot(ax = ax3, title = "df1", grid = 'on') df4.plot(ax = ax4, title = "df1", grid = 'on') plt.show()
运行结果如下
可以看出，随机生成了几个dataframe,在一个figure()中生成了四个子图，每个子图的图例都是dataframe.columns里的值，那么如何移除这些图例？
import pandas as pd import numpy as np import matplotlib.pyplot as plt fig = plt.figure(1) ax1 = fig.add_subplot(2,2,1) ax2 = fig.add_subplot(2,2,2) ax3 = fig.add_subplot(2,2,3) ax4 = fig.add_subplot(2,2,4) df1 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df2 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df3 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df4 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df1.plot(ax = ax1, title = "df1", grid = 'on') df2.plot(ax = ax2, title = "df1", grid = 'on') df3.plot(ax = ax3, title = "df1", grid = 'on') df4.plot(ax = ax4, title = "df1", grid = 'on') ax1.legend_.remove() ##移除子图ax1中的图例 ax2.legend_.remove() ##移除子图ax2中的图例 ax3.legend_.remove() ##移除子图ax3中的图例 plt.show()
可以看出ax1,ax2,ax3中的图例都被移除了，但是上图还不是很美观？有没有什么办法将图例放到图外面呢？请看:
import pandas as pd import numpy as np import matplotlib.pyplot as plt fig = plt.figure(1) ax1 = fig.add_subplot(2,2,1) ax2 = fig.add_subplot(2,2,2) ax3 = fig.add_subplot(2,2,3) ax4 = fig.add_subplot(2,2,4) df1 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df2 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df3 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df4 = pd.DataFrame(np.random.randn(3,5),columns = ['one','two','three','four','five']) df1.plot(ax = ax1, title = "df1", grid = 'on') df2.plot(ax = ax2, title = "df1", grid = 'on') df3.plot(ax = ax3, title = "df1", grid = 'on') df4.plot(ax = ax4, title = "df1", grid = 'on') ax1.legend_.remove() ax2.legend_.remove() ax3.legend_.remove() ax4.legend(loc=2, bbox_to_anchor=(1.05,1.0),borderaxespad = 0.) ##设置ax4中legend的位置，将其放在图外 plt.show()
其中参数loc用于设置legend的位置
bbox_to_anchor用于在bbox_transform坐标（默认轴坐标）中为图例指定任意位置。
