How to create a python virtual environment?

[hsieh42]

In Enthough canopy 2 (as a module python/canopy2/2.7 on cbica-cluster as of 2018/9/24):

## to create an empty python 2.7.x environment where x is the highest available.
$ edm environments create --version 2.7 ${env_name} 
$ edm shell -e ${env_name}

In Anaconda:

## to create an empty python 2.7.x environment where x is the highest available with
## some packages installed during setup.
$ conda create --name ${env_name} python=2.7 ${python_packages_to_be_preinstalled} 
$ source activate ${env_name}