已安装python，但是出现‘python’不是内部或外部命令，也不是可运行的程序或批处理文件。

解决方法：

1.打开python shell查看你的python安装路径（黄色标注）

>>> import sys
>>> sys.path
['', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37Lib\idlelib', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\python37.zip', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\DLLs', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37', 'C:\Users\Administrator\AppData\Roaming\Python\Python37\site-packages', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\site-packages', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\site-packages\win32', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\site-packages\win32\lib', 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\site-packages\Pythonwin']

2.右键计算机 -> 属性 -> 高级系统设置 -> 环境变量 -> 将上述路径添加到path变量中，注意不同环境变量之间用‘;’分隔