Virtual Environments with Python

Overview

Mac OS X Yosemite comes with Python 2.7 installed.

After installing Python 3.4, the python command still invokes Python 2.x. This can be overcome by using python3 instead.

Similarly, the pip command invokes pip that was installed with Python 2.x. So, sudo pip install [package_name] will install for Python 2.x and leave Python 3.x unchanged. pip3 can be used to update Python 3.x on the command line.

Creating virtual environments on Mac

First, install virtualenv if it is not already installed: sudo pip(3) install virtualenv. A new terminal shell is required to have the virtualenv command available.

$ virtualenv -p /Library/Frameworks/Python.framework/Versions/3.4/bin/python3 py3env
$ source py3env/bin/activate
$ pip install package-name

To find the path to Python 3.x:

$ which python3