Installing Python 3 on Mac OS X

The latest version of Mac OS X, Sierra, comes with Python 2.7 out of the box.

You do not need to install or configure anything else to use Python 2. These instructions document the installation of Python 3.

The version of Python that ships with OS X is great for learning, but it’s not good for development. The version shipped with OS X may be out of date from the official current Python release, which is considered the stable production version.

Doing it Right

Let’s install a real version of Python.

Before installing Python, you’ll need to install GCC. GCC can be obtained by downloading XCode, the smaller Command Line Tools (must have an Apple account) or the even smaller OSX-GCC-Installer package.

Note

If you already have XCode installed, do not install OSX-GCC-Installer. In combination, the software can cause issues that are difficult to diagnose.

Note

If you perform a fresh install of XCode, you will also need to add the commandline tools by running xcode-select --install on the terminal.

While OS X comes with a large number of UNIX utilities, those familiar with Linux systems will notice one key component missing: a package manager. Homebrew fills this void.

To install Homebrew, open Terminal or your favorite OSX terminal emulator and run

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

The script will explain what changes it will make and prompt you before the installation begins. Once you’ve installed Homebrew, insert the Homebrew directory at the top of your PATH environment variable. You can do this by adding the following line at the bottom of your ~/.profile file

export PATH=/usr/local/bin:/usr/local/sbin:$PATH

Now, we can install Python 3:

$ brew install python3

This will take a minute or two.

Pip

Homebrew installs pip3 for you.

pip3 is the alias for the Python 3 version of pip on systems with both the Homebrew’d Python 2 and 3 installed.

Working with Python 3

At this point, you have the system Python 2.7 available, potentially the Homebrew version of Python 2 installed, and the Homebrew version of Python 3 as well.

$ python

will launch the Python 2 interpreter.

$ python3

will launch the Python 3 interpreter.

pip3 and pip will both be available. If the Homebrew version of Python 2 is not installed, they will be the same. If the Homebrew version of Python 2 is installed then pip will point to Python 2 and pip3 will point to Python 3.

Virtual Environments

A Virtual Environment (commonly referred to as a ‘virtualenv’) is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them. It solves the “Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keeps your global site-packages directory clean and manageable.

For example, you can work on a project which requires Django 1.10 while also maintaining a project which requires Django 1.8.

To start using this and see more information: Virtual Environments docs.


This page is a remixed version of another guide, which is available under the same license.