# Numina Deployment with Virtualenv

Virtualenv is a tool to build isolated Python environments.

It’s a great way to quickly test new libraries without cluttering your global site-packages or run multiple projects on the same machine which depend on a particular library but not the same version of the library.

## Install Virtualenv

To install globally with pip (if you have pip 1.3 or greater installed globally):

    $ sudo yum install python-virtualenv

For other ways of installing the package, check virtualenv_install webpage.

## Create Virtual Environment

We urge reader to read the virtualenv_usage webpage to use and create new virtual environments.

As an example, a new virtual environment named numina is created where no packages but pip and setuptools are installed:

    $ virtualenv numina

## Activate the Environment

Once the environment is created, you need to activate it. Just go to bin/ folder created under numina and load with your command line interpreter the script bin/activate:

    $ cd numina/bin
    $ source activate
    (numina) $

Notice that the prompt changes once you are activate the environment. To deactivate it just type deactivate:

    (numina) $ deactivate
    $

## Numina Installation

Numina is registered in the Python Package Index. That means (among other things) that can be installed inside the environment with one command:

    (numina) $ pip install numina

The requirements of numina will be downloaded and installed inside the virtual environment automatically.