Setting up and using Python3, Pip3, Virtualenv (for Python3) and Virtualenvwrapper (for Python3)

Python3, Pip3, Virtualenv and Virtualenvwrapper Setup

First install pip for Python2. Download the get-pip.py file from https://bootstrap.pypa.io/get-pip.py
$ cd <download location>
$ sudo -H python ./get-pip.py

Installing pip also installs Python3
To run Python3
$ python3

Install pip3 by just executing the same file as in the step above, but this time using Python3
$ sudo -H python3 ./get-pip.py

To install virtualenv via pip
$ sudo -H pip3 install virtualenv

{If you want to use virtualenv as is, read below, else skip to the next pair of braces}

Note that virtualenv installs to the python3 directory. For me it's:
$ /usr/local/share/python3/virtualenv

Create a virtualenvs directory to store all virtual environments
$ mkdir somewhere/virtualenvs

Make a new virtual environment with no packages
$ virtualenv somewhere/virtualenvs/<project-name> --no-site-packages

To use the virtual environment
$ cd somewhere/virtualenvs/<project-name>/bin
$ source activate

You are now using the virtual environment for <project-name>. To stop:
$ deactivate

{Continue installation}

To install virtualenvwrapper
$ sudo -H pip3 install virtualenvwrapper

Use the following command to find the location of Python3 on your system
$ which python3

Add the following lines to ~/.bashrc (or your own shell's initialisation file)
> VIRTUALENVWRAPPER_PYTHON='<Python3 location>'
> source /usr/local/bin/virtualenvwrapper.sh
> WORKON_HOME=$HOME/.virtualenvs

Run the following commands
$ mkdir ~/.virtualenvs
$ source ~/.bashrc

All the virtual environments created using virtualenvwrapper will now be stored in ./virtualenvs

To create new Python3 virtual environment
$ mkvirtualenv <project-name>

To create new Python2 virtual environment
$ mkvirtualenv --python=python2 <project name>

The virtualenv will automatically activate after creation

Install packages local to the python3 virtualenv (and not global to the system) using
$ pip3 install <package-name>

Install packages local to the python2 virtualenv (and not global to the system) using
$ pip install <package-name>

To exit the virtualenv
$ deactivate

To get back into the virtualenv
$ workon <project-name>

I believe an export may be missing here:

> VIRTUALENVWRAPPER_PYTHON='<Python3 location>'

shouldn't it be

> export VIRTUALENVWRAPPER_PYTHON='<Python3 location>'

according to this section of the install guide: http://virtualenvwrapper.readthedocs.io/en/latest/install.html#python-interpreter-virtualenv-and-path

@MYeager1967 As far as I know yes, python programs employing graphics libraries (such as Tkinter, and Pygame) will run in the virtual environment.

@asugai You need export to make the the variable available to any child processes. Since I'm only ever running the virtualenvs in the shell and since every time a new shell instance is created it reloads the configuration, we don't need to add export at the beginning of the command inside the shell's config file.
However, if you were to declare the variable manually every time you opened the shell (which would be inconvenient) then yes you can append export to the beginning of the statement.

Relevant stackoverflow post

Mac Users, who have propblems with virtualenvwrapper - It needs to be installed seperately like so: pip3 install virtualenvwrapper