没有为logger'matplotlib.lengend'找到处理程序

Question

import numpy as np
import matplotlib.pyplot as plt
X = np.linspace(-np.pi, np.pi, 256, endpoint=True)
C, S = np.cos(X), np.sin(X)

plt.plot(X, S, color = 'green', linewidth = 1.0, linestyle = '-')
plt.plot(X, C, color = 'blue', linewidth = 1.0, linestyle = '-')

plt.xlim(-4.0, 4.0)

plt.xticks(np.linspace(-4, 4, 9, endpoint=True))

plt.ylim(-1.0, 1.0)

plt.yticks(np.linspace(-1, 1, 5, endpoint=True))

plt.legend(loc = 'upper left', frameon = False)

plt.show()

当我运行这个python代码时，我看到的是情节而不是图例，并将输出结果显示为：No handlers could be found for logger "matplotlib.legend"

Answer 1

我忘了给plot（）函数添加标签。添加后，它工作正常。