How to Install Python 3.6 along with Python 2.7?

Question

Python Newbie here. I just bought a new Mac that came with Python 2.7. I'm using the older version of Python for a class so I need to keep it. I want to install the latest version of Python, 3.6, side by side the older version. The instruction I found online were either outdated or confusing. Can anyone point me in the right direction?

Answer 1

You can use brew to install python3.

$ brew install python3
$ python # to start the python 2.7
$ python3 # to start the python 3

This is the simplest way to get started with python 3 on macOS.

Answer 2

if you download anaconda, a very common download for python development, you get a great package manager and a very easy way to create sandboxed environments. After downloading anaconda (for your current Python, so 2.7), you can open up your terminal and enter:

conda create my_new_env_name python=3.6

that will create a new sandboxed environment with python3.6. to use that environment, enter in your shell

source active my_new_env_name

now if you enter python from the shell you're in python3.6, or you can run python somefile.py from the shell to run it in python3.6

This is a great way to maintain and manage different versions of libraries on your system as well. For example, if you need an old version of a specific Python library for a particular project, but don't want to downgrade that library for all your Python code.

More on managing conda environments at the documentation page