[matplotlib-devel] Using `hexbin` with `edgecolors = 'none'`

[Tony Yu <ts...@gm...>]

I'm drawing hexbins with alpha < 1 and get dark lines at the bin edges. It
turns out that setting `edgecolors = 'none'` sets the edge color to be the
same as the face color, as mentioned in the docstring:

           If ``'none'``, draws the edges in the same color as the fill
color.
           This is the default, as it avoids unsightly unpainted pixels
           between the hexagons.

This behavior is a bit weird, since setting colors to 'none' usually makes
the element invisible. Wouldn't it be more consistent to let 'none' be
passed to the PolyCollection (which draws the hexbins), such that edges
aren't drawn. Then, to maintain the current behavior, change the default to
'face'. (Of course, this wouldn't really maintain current behavior for code
that explicitly passes `edgecolors='none'`.)

Also, if I let 'none' get passed to the PolyCollection, I don't see the
"unsightly unpainted pixels between the hexagons". Is this just a
system-dependent artifact, or is it an outdated docstring?

Thanks,
-Tony