import matplotlib.pyplot as plt import numpy as np x = np.arange(0, 2*np.pi, 0.02) y = np.sin(x) y1 = np.sin(2*x) y2 = np.sin(3*x) ym1 = np.ma.masked_where(y1 > 0.5, y1) ym2 = np.ma.masked_where(y2 < -0.5, y2) lines = plt.plot(x, y, x, ym1, x, ym2, ‘o‘) plt.setp(lines[0], linewidth=4) plt.setp(lines[1], linewidth=2) plt.setp(lines[2], markersize=10) plt.legend((‘No mask‘, ‘Masked if > 0.5‘, ‘Masked if < -0.5‘), loc=‘upper right‘) plt.title(‘Masked line demo‘) plt.show()
ym1 = np.ma.masked_where(y1 > 0.5, y1)这句的意思是:ym1是所有y1值小于0.5的y1的集合
ym2 = np.ma.masked_where(y2 < -0.5, y2)这句的意思是:ym2是所有y2值大于﹣0.5的y2的集合
lines = plt.plot(x, y, x, ym1, x, ym2, ‘o‘)和plt.legend((‘No mask‘, ‘Masked if > 0.5‘, ‘Masked if < -0.5‘),loc=‘upper right‘)配合使用可以给图标注释python中ma.masked_where的用法和legend的用法
原文：https://www.cnblogs.com/qingnvsue/p/13051363.html