How do i use pip & virtualenv to create virtual python environments?

amurleopard

This has nothing to do with virtual machines. It means create a sandbox area to use specific python versions and software relating to that version.

If you have Python 2 >=2.7.9 or Python 3 >=3.4 installed from python.org, you will already have pip and setuptools, but will need to upgrade to the latest version.

You can use the package manager to install pip for various OS's.
eg: for ubuntu

$ sudo apt-get install python-pip

After install, to upgrade pip

$ pip install -U pip setuptools

Check if it is installed. This is PATH dependent.

$ which virtualenv
/usr/local/bin/virtualenv

Otherwise install pip

$ pip install virtualenv

Create a virtual python environment

$ mkdir jospizza
$ cd jospizza/

Check where various version are installed.

$ which python3
/usr/bin/python3
$ which python3.4
/usr/bin/python3.4
$ which python2.7
/usr/bin/python2.7

Create a virtual python environment.

$ virtualenv -p /usr/bin/python3.4 .jospizza
Running virtualenv with interpreter /usr/bin/python3.4
Using base prefix '/usr'
New python executable in /home/trainer/jospizza/.jospizza/bin/python3.4
Also creating executable in /home/trainer/jospizza/.jospizza/bin/python
Installing setuptools, pip, wheel...done.
$ source .jospizza/bin/python
bash: source: .jospizza/bin/python: cannot execute binary file
$ source /home/trainer/jospizza/.jospizza/bin/python
bash: source: /home/trainer/jospizza/.jospizza/bin/python: cannot execute binary file
$ source .jospizza/bin/activate
(.jospizza) $ which python
/home/trainer/jospizza/.jospizza/bin/python
(.jospizza) $ python -V
Python 3.4.0
(.jospizza) $ deactivate
$

Each time you are developing code with python3.4, you activate your venv.

"Beginning with Python 3.4, venv (a stdlib alternative to virtualenv) will create virtualenv environments with pip pre-installed, thereby making it an equal alternative to virtualenv."

$ python3.4 -m venv jodiner