System Message: WARNING/2 (/build/buildd/matplotlib-0.98.3/doc/api/backend_qt4agg_api.rst, line 5)
autodoc can’t import/find module ‘matplotlib.backends.backend_qt4agg’, it reported error: “cannot import name QtCore”,please check your spelling and sys.pathmatplotlib.backends.backend_gtkagg
matplotlib.backends.backend_wxagg