A commonly used data analysis framework is root (http://root.cern.ch). It offers a object oriented C++ framework with all kind of things one needs for plotting and data visualization. It comes along with PyRoot, an interface making the root objects available to Python. Take a look at the root manual for examples, it also contains a section describing the use of PyRoot.
Cheers! Bernhard -- http://mail.python.org/mailman/listinfo/python-list
