如果遇到问题：
__main__:1: UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure.
解决方案：
在程序中增加一条语句：
import matplotlib
matplotlib.use(‘TkAgg‘) （增加这条语句）
matplotlib之__main__:1: UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure.
原文：https://www.cnblogs.com/elitphil/p/12221345.html
