There are several examples on this site on how to call Mathematica from Python.  You can:

 * [install the bindings](http://mathematica.stackexchange.com/q/4643/7167) that come with Mathematica; or 
 * [call a script as a subprocess](http://mathematica.stackexchange.com/q/39546/7167) from within Python; or even
 * [set up a pipe](http://mathematica.stackexchange.com/q/41742/7167) and interact with it from your script.

There are some good reasons to interact with Mathematica through Python, especially since the language is [highly touted on the Raspberry Pi](http://www.raspberrypi.org/learning-python-with-raspberry-pi/).  The Python bindings for Mathematica aren't available on the RPi version, however.  Even pulling the bindings from another installation seems to have problems.  So *how does one get Mathematica and Python to talk nicely on the Raspberry Pi*?