Matplotlib can't find font installed in my Linux machine

Question

I am trying to draw an xkcd-style plot with matplotlib (ver. 1.4.2) under Python 3.

When I try to run:

import matplotlib.pyplot as plt
plt.xkcd()
plt.plot([1,2,3,4], [1,4,9,16], 'bo')
plt.axis([0, 6, 0, 20])
plt.show()

It opens an empty window without any image and I get the error:

/usr/lib/python3/dist-packages/matplotlib/font_manager.py:1279: UserWarning: findfont: Font family ['Humor Sans', 'Comic Sans MS', 'StayPuft'] not found. Falling back to Bitstream Vera Sans
  (prop.get_family(), self.defaultFamily[fontext]))
/usr/lib/python3/dist-packages/matplotlib/font_manager.py:1289: UserWarning: findfont: Could not match :family=Bitstream Vera Sans:style=normal:variant=normal:weight=normal:stretch=normal:size=medium. Returning /usr/share/matplotlib/mpl-data/fonts/ttf/STIXSizOneSymReg.ttf
  UserWarning) Exception in Tkinter callback

I have Humor Sans installed. I checked it with fc-list | grep Humor. It can also be used within other programs, like Libre Office. I also have staypuft installed. Isn't that enough?

The same code above but without the plt.xkcd() bit works flawlessly.

An alternative to plt.show(), like pylab.savefig() won't work either for the xkcd code, but doesn't have any problem with the same code without using xkcd.

Answer 1

If you add a new font after installing matplotlib then try to remove the font cache. Matplotlib will have to rebuild the cache, thereby adding the new font.

It may be located under ~/.matplotlib/fontList.cache or ~/.cache/matplotlib/fontList.json.

Answer 2

For Mac User: try to run this command in python: (or before the .py file)

import matplotlib

matplotlib.font_manager._rebuild()