Matplotlib 1.5 broken_barh fails on empty data. #5572
Description
A change from 1.4 to 1.5 has caused subplots to not be able to plot broken bars where the xrange has no data. Previously an empty list as xranges worked fine (no data was added to the subplot). Now it throws an IndexError exception:
File "/home/travis/build/cuthbertLab/music21base/music21/graph.py", line 1058, in process
ax.broken_barh(xranges, yrange, facecolors=faceColor, alpha=self.alpha)
File "/home/travis/miniconda2/lib/python3.4/site-packages/matplotlib/__init__.py", line 1811, in inner
return func(ax, *args, **kwargs)
File "/home/travis/miniconda2/lib/python3.4/site-packages/matplotlib/axes/_axes.py", line 2336, in broken_barh
self._process_unit_info(xdata=xranges[0],
IndexError: list index out of range
This could be considered a backwards-incompatible issue. Or maybe a feature. In any case, it was something that my toolkit (music21) was counting on being able to use in some cases; a simple "if len(xranges) > 0:" wrap around the call fixed it.