Python Virtual Environments
Virtual environments are used in Python to allow different requirements to exist and different dependencies to be used in different Python projects on the same computer. For example, a developer may start creating a project using Foo version 0.5. The project may take many months to complete or be ongoing. However, in the meantime the commands and functionality of Foo are radically changed with the introduction of Foo versions 1.0 and 2.0. In order that the developer can continue to use Foo version 0.5, she would set up a virtual environment and install version 0.5. This would not affect other environments using later versions of Foo. Virtual environments are easy to install and use in Python.
pip3 install --user virtualenv
Then in the project directory, simply use to initialize the Python virtual environment.
python3 -m venv env
This will create a separate Python install for the project. To begin using that particular Python virtual environment, simply type: source env/bin/activate Then you will be in the virtual Python environment. To stop using the virtual environment, simply type: deactivate
See also: here.
Exporting and Importing Python Virtual Environments
In order to create a Python virtual environment,
use pip i.e. pip3 to get a list of requirements:
pip3 freeze > requirements.txt
Create your environment:
virtualenv my_env
Start using the environment:
source my_env/bin/activate
Use pip to install the requirements:
pip3 install -r requirements.txt