python-environment-notes.md

Python Environment Notes

Using pyenv for working with Python versions

You can use pyenv to work with different versions of python.

To install:

$ brew install pyenv

Pyenv works with shims. To use them, we need to add this to our shell config:

eval "$(pyenv init -)"

Install a version of Python:

$ pyenv install 3.6.0

Use a pyenv version globally:

$ pyenv global 3.6.0

Use a pyenv version locally:

$ pyenv local 3.6.0

This will add a .python-version file to the local directory. When you enter this directory, pyenv will recognize the version of Python you want to use. If this version is not installed, pyenv will let you know you need to install it.

Managing a virtual environment with pyenv-virtualenv

pyenv-virtualenv will allow you to set the version of Python you want to use for a project, and have a contained set of packages (like having a separate gemset in the Ruby world).

Install:

$ brew install pyenv-virtualenv

Create a new environment:

$ pyenv virtualenv 3.6.0 my-project-3.6.0

List virtual envs:

$ pyenv vitualenvs

Remove a virtual env:

$ pyenv uninstall my-project-3.6.0

Use a virtual env for the current project:

$ pyenv local my-project-3.6.0

Figure out the location of python

Sometimes you want to know where the location of the installed python you are using is:

$ pyenv which python

Installing a package

You can use the pip package manager to install a package:

$ python -m pip install pylint

Dependency management

After installing a pip package, you can create a requirements file that other can use to load the same packages:

$ python -m pip freeze > requirements.txt

Then someone else can load the requirements file:

$ python -m pip install -r requirements.txt