I'm using the following LaTeX code in a Beamer presentation:

\begin{frame}\begin{figure}\centering\tiny\lstset{language=python}\lstinputlisting{code/get_extent.py}\end{figure}
\end{frame}

Is it possible to select specific lines from my get_extent.py file rather than displaying it all?

This has nothing to do with beamer; it's about a listings feature. Its excellent manual has more. For example:

\lstinputlisting[firstline=2,lastline=5]{code/get_extent.py}