pip 安装问题

1.pip 安装总是出现超时 失败

• 解决办法 更换下载网址 这里使用豆瓣的 
• pip install -i https://pypi.doubanio.com/simple/ 包名 
• pip install -i https://pypi.doubanio.com/simple/ flask

2.Windows 下：ModuleNotFoundError: No module named 'win32api'

• 解决办法  安装win32api
•  pip install pypiwin32
• 若失败可手动下载安装对应版本 https://sourceforge.net/projects/pywin32/files/pywin32/

3.You are using pip version 10.0.0b2, however version 18.0 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.

• 解决办法安装的pip的版本太低，升级即可
• python -m pip install --upgrade pip

4.安装Scrapy报错 Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools": 

• 解决办法 scrapy是依赖于 Microsoft Visual C++ 14.0编译器
• 办法1，安装Microsoft Visual C++ 14.0编译器，缺点包大，下载不太顺利，占资源
• 办法2，只需安装Twisted包即可，https://www.lfd.uci.edu/~gohlke/pythonlibs/#twisted 找到对应版本，下载后安装 pip install F:\python\Twisted-18.7.0-cp36-cp36m-win_amd64.whl