http://stackoverflow.com/a/9773312
I had the same issue and solved it by setting the appropriate display backend, following matplotlib does not show my drawings although I call pyplot.show()
There are two ways to achieve this:
1.Set the backend in your code, right after importing matplotlib:
import matplotlib
matplotlib.rcParams['backend'] = "Qt4Agg"
2.Or define your backend inside your matplotlibrc file (as given by matplotlib.matplotlib_fname()):
backend : Qt4Agg
More information here: http://matplotlib.sourceforge.net/users/customizing.html