Installing Python packages with pip

You now know how to define your project's dependencies in a setup.py script. But how do you install those dependencies? How do you upgrade a dependency or replace it when you find a better one? How do you decide when it is safe to delete a dependency you no longer need? Managing project dependencies is a tricky business. Luckily, Python comes with a tool called pip that can help, especially in the early stages of your project.

The initial 1.0 release of pip arrived on April 4, 2011, around the same time that
Node.js and npm were taking off. Before it became pip, the tool was named pyinstall. pyinstall was created in 2008 as an alternative to easy_install, which came bundled with setuptools at the time. easy_install is now deprecated and setuptools recommends using pip instead.

Since pip is included with the Python installer and you can have multiple versions of Python installed on your system (for example, 2.7 and 3.8), it helps to know...