Startup Guide for Python

Python is a way to get your hands on powerful development tools, but in its own ways needs to be managed.

tl;dr

Install the latest release from python.org for general purpose usage, or manage multiple versions of Python using pyenv (which can be installed view homebrew). Install packages to individual projects with separate virtual environments using venv.

common commands

While Python has it's own interactive interpreter, a common way to interact with python will take place through a shell) terminal.

version number

python3 -v
# or use
python3 --version

install pips

pip install -r requirements.txt

create a virtual environment using venv

python3 -m venv env

activate an environment

source env/bin/activate

or you can run a script using that environment

env/bin/python3 script.py

freeze pips

pip freeze > requirements.txt

Continue below for a more in depth discussion on setting up a development environment for Python.

basic installation

If you're using Python for a single project, you might be able to get away with just installing the latest release from python.org (the official webpage for the language). If you're using Python regularly, you've probably encountered situations where different projects require different versions of Python itself. Whether it's code breaking changes being made to the next version, or maybe a pip is just out of date, managing Python versions on your machine globally becomes increasingly important.

pip

The most useful thing about Python is the immense repository of packages that are available for use. A package/dependency is referred to as a pip (Preferred Installer Programs from the Python Package Index). When using pips we can very easily integrate powerful libraries into our projects by installing them via the command line:

pip install <package-name>
# python must be installed for this to work

You can list the pips that have been installed using pip list, and you can even write those pips to text file as a quick reference when setting up the project on another computer using the freeze and install commands.

# write to a file
pip freeze > requirements.txt

And now when our project is moved to a new machine, we can grab the dependencies by simply running:

# install list of pips
pip install -r requirements.txt

venv

A common practice is to organize our pips by project, since we may not need the same packages for separate projects. This is done through a virtual environment. While there are a ton of packages and methods to handle this task, my preferred method is the venv module, native to Python since version 3.3.

Once python is installed you can create a new environment by running:

python3 -m venv env
# creates a folder named 'env'

After creating our env directory, you can activate that python environment by running:

source env/bin/activate

When you install packages via pip, these dependencies will be stored in the env directory. The one issue with venv is that it can only create environments in the same Python version as the one it was created with. In order to use multiple versions of Python on your machine, we can use pyenv.

pyenv

The documentation for pyenv recommends using homebrew for installation. So after installing homebrew you can run:

brew install pyenv

To install a version of python:

pyenv install 3.10.4

You can get a list of all the available versions of python using

pyenv install -l

Switch between different versions of python that are installed using the global command.

pyenv global 3.10

After properly configuring pyenv we can now create virtual environments for any version of python we've installed by switching to that installation and running python3 -m venv <environment-name> in the directory where we want the environment to exist.

cool & helpful links

dataquest - installing python on mac

textual guide

object oriented programming