title: MatplotlibDeprecationWarning with Pyinstaller .exe
body: <p>I have run into a warning that only appears when the pyinstaller executable is run. </p>
  
  <pre><code>...appdata\local\programs\python\python37-32\lib\site-packages\PyInstaller\loader\pyimod03_importers.py:627: MatplotlibDeprecationWarning:
  The MATPLOTLIBDATA environment variable was deprecated in Matplotlib 3.1 and will be removed in 3.3.
    exec(bytecode, module.__dict__)
  </code></pre>
  
  <p>I have tried all of the suggestions here: <a href="https://stackoverflow.com/questions/24502500/python-matplotlib-getting-rid-of-matplotlib-mpl-warning">Python/matplotlib : getting rid of matplotlib.mpl warning</a></p>
  
  <p>I have also tried this without any change in the end result: 
  <a href="https://stackoverflow.com/questions/22315907/pyinstaller-exe-hide-warning-messages">Pyinstaller exe hide warning messages</a></p>
  
  <p>without any change in the MatplotlibDeprecation warnings appearing in the final executable. The warnings are baseline not present when running the code in an IDE such as Pycharm.</p>
  
  <p>Using: 
  Python 3.7.2
  Pyinstaller 3.5
  Matplotlib 3.1.1</p>