https://blog.csdn.net/Poul_henry/article/details/82533569
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
print x
fig = plt.figure()
ax = plt.subplot(111)
for i in xrange(5):
#ax.plot(x, i * x, label='y=%dx' %i)
ax.plot(x, i * x, label='$y = %ix$' % i)
ax.legend()
plt.show()
