1. 安装python2.7和python3.5
2. 添加python2.7和python3.5的环境变量
- C:\Python27
- C:\Python27\Scripts
- C:\Python35
- C:\Python35\Scripts
3. 进入python2.7的安装目录，python.exe重命名为python2.exe
4. 进入python3.5的安装目录，python.exe重命名为python3.exe
5. 在cmd中调用python2和python3
- 输入python2可以调用python2.7
- 输入python3可以调用python3.7
6. 在不用python版本下调用pip安装软件
python2 -m pip install numpy //安装
python2 -m pip list //
python2 -m pip install --upgrade pip //更新
