Python 2

Make an environment from a list of desired packages

emacs requirements.txt
mkdir first_light
virtualenv ./first_light/
(virtualenv --python=/usr/bin/python3 venv)
(virtualenb -p python3 venv)
source ./first_light/bin/activate
pip install -U -r requirements.txt

Open environment

$ source ./first_light/bin/activate

Save Requirements

$ pip freeze > requirements.txt

Python 3

Just use the built-in alternative to virtualenv:

$ pyvenv-3.3 ./all_venvs/desired_venv_name
$ source ./all_venvs/desired_venv_name/bin/activate

Cluster management of virtual environment

On Sherlock cluster, must first run

$ module load python/3.3.2

Otherwise will get error

python: error while loading shared libraries: cannot open shared object file: No such file or directory

Updating/importing libraries on a managed cluster

Setup (can do this either within or outside of venv)

$ easy_install-3.3 --user pip
$ export PATH=~/.local/bin:$PATH
$ pip3.3 install --user scipy numpy matplotlib