Histograms with negative data

Engelsma,> Any ideas?

The following script, all negative data, works fine for me:

    from matplotlib.matlab import *

    x = randn(1000)-10
    hist(x, 10)

Make sure this example works for you (if not upgrade matplotlib), and
then go back to your example. Take out all the customization stuff
after the call to

  n, bins, patches = matplotlib.matlab.hist(histogram_data, 10,

and see if that works. If so, slowly add things back until you find
out what is wrong. If it's a matplotlib error rather than an error on
your side, let me know.