Description of problem: Installing the ipython package does not correctly install all dependencies necessary to use the "pylab" mode. Trying the magic "%pylab" or starting with "--pylab" will yield the error message ERROR: pylab mode doesn't work as matplotlib could not be found. Is it installed on the system? Importing matplotlib via "import matplotlib" works fine, but using the common "import matplotlib.pyplot as plt" yields the error message ImportError: No module named backend_qt4agg Installing the "python-matplotlib-qt4" package solves the problem. I think either the "python-ipython" package, or at least "python-ipython-gui" package should depend on "python-matplotlib-qt4". This was tested on a fresh install of Fedora 20.
The default backend in matplotlib will be GTKAgg with a forthcoming update. Then it will be fine to just require python-matplotlib. When you change your default backend in python-matplotlib yourself, then you should also install the correct subpackage of python-matplotlib yourself. Closing as an duplicate of the corresponding matplotlib bug. *** This bug has been marked as a duplicate of bug 1049624 ***