BUG: allow facecolors to be overridden in LineCollection

[jakevdp]

Very small change, fully backward compatible.

Current behavior is this:

import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection
import numpy as np

points = np.random.rand(5, 3, 2)
colors = plt.cm.jet(np.linspace(0, 1, 5))
coll = LineCollection(points, facecolors=colors)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-66-7da275dddf5c> in <module>()
      5 points = np.random.rand(5, 3, 2)
      6 colors = plt.cm.jet(np.linspace(0, 1, 5))
----> 7 coll = LineCollection(points, facecolors=colors)

/Users/jakevdp/anaconda/envs/py3k/lib/python3.3/site-packages/matplotlib/collections.py in __init__(self, segments, linewidths, colors, antialiaseds, linestyles, offsets, transOffset, norm, cmap, pickradius, zorder, **kwargs)
   1081             pickradius=pickradius,
   1082             zorder=zorder,
-> 1083             **kwargs)
   1084 
   1085         self.set_segments(segments)

TypeError: __init__() got multiple values for keyword argument 'facecolors'

[WeatherGod]

Maybe a quick little explanation of what it means for a line collection to have a facecolor?

[jakevdp]

Done

[jakevdp]

I should add: the reason this is useful is that you can use line collections to draw filled polygons from vertices alone, without the need to explicitly wrap each set of vertices in a Path as in, e.g. PathCollection. My current workaround is:

coll = LineCollection(points)
coll.set_facecolors(colors)

which works, but it took a bit of digging to figure out why LineCollection was telling me I passed facecolors twice in the more intuitive use above.

[WeatherGod]

Correct. It can just a little non-obvious that a LineCollection can have a facecolor. Will merge once Travis is happy.