子图

import matplotlib.pyplot as plt
import numpy as np
x = np.arange(1,100)
fig = plt.figure()
ax1 = fig.add_subplot(221)
ax1.plot(x,x)
ax2 = fig.add_subplot(222)
ax2.plot(x,-x)
ax3 = fig.add_subplot(223)
ax3.plot(x,x**2)
ax4 = fig.add_subplot(224)
ax4.plot(x,-x*2)
plt.show()