python matplotlib 中文显示参数设置

refer to: 

https://segmentfault.com/a/1190000005144275

#coding:utf-8
import matplotlib.pyplot as plt
plt.rcParams['font.sans-serif']=['SimHei'] #用来正常显示中文标签
plt.rcParams['axes.unicode_minus']=False #用来正常显示负号