I am using Anaconda with Python 3.5.2, Matplotlib 2.0.2, PyQt5.6 on a windows 10 machine. When I import matplotlib.pyplot as plt I get the following error:
...
Looking at the file and line number in your error it looks that you have the same issue that I answered here.
That is, I think your issue is caused by having a QT_API environment variable that still is set to pyqt4 (or pyside).
QT_API
pyqt4
pyside