Created by: luckeriam

在输出图像的时候提示：

/opt/conda/envs/python-3.6/lib/python3.6/site-packages/ipykernel_launcher.py:3: UserWarning: This call to matplotlib.use() has no effect because the backend has already been chosen; matplotlib.use() must be called before pylab, matplotlib.pyplot, or matplotlib.backends is imported for the first time.