Python uses the virtualenvwrapper module to create virtual environments

One, installation

on Windows

pip install virtualpip install virtualenvwrapper-win

on macOS / Linux

pip install --user virtualenvwrapperecho "source virtualenvwrapper.sh" >> ~/.bashrcsource ~/.bashrc

Second, create a virtual environment

on Windows

Create a virtual environment to the specified directory and modify the twenty-four lines of the E:\python3.7.6\Scripts\mkvirtualenv.bat file as follows:

set "venvwrapper.default_workon_home=E:\python3.7.6\Envs"

mkvirtualenv --python=python3 myenv

on macOS/Linux

mkvirtualenv --python=python3.6 myenv

Three, activate the environment

Set the workon environment variable, operation: environment variable --> system variable --> new: variable name: WORKON_HOME variable value: E:\python3.7.6\Envs

workon lists the virtual environment list

workon [myenv] switch environment

Four, exit the environment

deactivate

Five, delete the environment

rmvirtualenv myenv

Six, other useful instructions

1.pip freeze to view the current installed library version

Create a requirements.txt file that contains a simple list of all packages and their respective versions in the current environment

pip freeze > requirements.txt

2. Keep the deployment the same, install all packages with one click

pip install -r requirements.txt

3. List all environments

lsvirtualenv

4. Navigate to the directory of the currently activated virtual environment, equivalent to the pushd directory

cdvirtualenv

5. Similar to the above, go directly to the site-packages directory

cdsitepackages

6. Display the contents of the site-packages directory

lssitepackages

7. Download through the domestic Tsinghua mirror

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