1，不知道为啥
py -3 -m pip install matplotlib
这样安装会报错/缺少freetype和png组件/最后也没解决问题/
解决方法：
https://www.lfd.uci.edu/~gohlke/pythonlibs/#pyside
找到Matplotlib, a 2D plotting library.
安装matplotlib的必备组件：Requires numpy, dateutil, pytz, pyparsing, kiwisolver, cycler, setuptools, and optionally pillow, pycairo, tornado, wxpython, pyside, pyqt4, ghostscript, miktex, ffmpeg, mencoder, avconv, or imagemagick.
再下载相关的whl文件用pip安装即可！
原文：https://www.cnblogs.com/imaye/p/8961655.html