How to install a missing python package from inside the script that needs it?

Question

Assuming that you already have pip or easy_install installed on your python distribution, I would like to know how can I installed a required package in the user directory from

Answer 1

I wanted to note that the current accepted answer could result in a possible app name collision. Importing from the app namespace doesn't give you the full picture of what's installed on the system.

A better way would be:

import pip

packages = [package.project_name for package in pip.get_installed_distributions()]

if 'package' not in packages:
    pip.main(['install', 'package'])