Use virtual environments to develop Python code

What

• I like to think of virtual environments as package bookshelves for each of my projects. If I’m working on a cooking project, there is no need for me to have a book on surfing.
• Creates special isolated environments where all the packages and versions you install only apply to that specific environment. It’s like a private island! — but for code.

Why

• Having only the packages I need on my “bookshelf” eliminates all chances for me to possibly experience gross global installation and package collision errors and allows me to focus on what really matters — my code.
• Just like packages, I can also specify what specific version of python I want for my project.
• You can organize your packages much better and know exactly the packages you need to run your code incase someone else needs to run it on their machine
• Your main Python package directory does not get flooded with unnecessary Python packages

How

virtualenv

• Avoid the use of after Python 3.3+.

venv

# create a python3 environment within ".venv" folder
$ python3 -m venv .venv

# activate the environment
$ source .venv/bin/activate

# deactivate the environment
$ deactivate

• Make sure it correctly points to the distribution in your virtual environment, and not your global distribution, via which python and which pip. If it doesn't work well, you can always make sure you use the right one by specifying the path to pip and/or python when calling them, e.g. ./.venv/bin/pip3 list.

pyenv

• Used to isolate Python versions within your machine.

pipenv

• It is a venv on steroids: it strives to combine pipfile, pip and venv into a single command.

# install pipenv
$ pip install pipenv

# create environments
$ pipenv env

• Use the command pipenv (instead of pip) to install all your packages.
• Allows you to:
  • specify into which environment you install the package
  • integrate directly with PyPi or a local repository
  • create a single pipfile with separate sections for each environment (this is an alternative to the requirements.txt file required for each environment with virtualenv and venv)
  • pipenv lock your virtual environment; this creates a pipfile.lock file that resolves all dependencies required for a build
• The biggest advantage pipenv brings, in my opinion, is how it handles dependency management compared to requirements.txt and pip freeze.

direnv

• When you cd into a directory containing a .env, it automatically activates the environment.

Summary

Depending on the scope of your project, I ultimately suggest two options: venv and pipenv. If you do not need all the bells and whistles that pipenv brings, I suggest that you give venv a look. On the other hand, if that pipenv list struck out to you, go ahead and use that!