Python

Create Virtual environments with pyvenv

Let’s create a new virtual envirnoment, named myenv, using pyvenv:
pyvenv myenv3

source myenv3/bin/activate

and you can start Python 3 by just typing:
$ python

Note that as you are inside the virtual environment, you don’t need to use the command python3 to open Python 3.

Virtualenvwrapper with Python 3

$ pip install virtualenv
$ pip install virtualenvwrapper

Next, create a folder that will contain all your virtual environments:

$ mkdir ~/.virtualenvs
Open your .bashrc file and add:

export WORKON_HOME=~/.virtualenvs
source /usr/local/bin/virtualenvwrapper.sh
you can activate these changes by typing

$ source .bashrc
We are ready to create a new virtual environment using Python 3 with

$ mkvirtualenv --python=python3_path myenv3
where python3_path is the path of python3, which can be found with

$ which python3
in my case it was

$ mkvirtualenv --python=/usr/local/bin/python3 myenv
This creates a folder myenv inside the environments folder ~/.virtualenvs.The new environment will be active after running the previous command. To deactivate it, just type:

$ deactivate
and to activate it again

$ workon myenv
While being in your python3 virtual envirnoment, if you type

$ python

Original Link:
http://www.marinamele.com/2014/07/install-python3-on-mac-os-x-and-use-virtualenv-and-virtualenvwrapper.html