解决pip install 失败问题，WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError

 WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Read timed out. (read timeout=15)")':

转载自：https://blog.csdn.net/Miracle0_0/article/details/96971984

NOTE：清华源。(亲测，可用！@2019年11月)

例如：

pip install -i https://pypi.tuna.tsinghua.edu.cn/simple numpy