Repository navigation
[Bug]: gapcolor not supported for LineCollections #24796
Description
Bug summary
LineCollection doesn't have a get_gapcolor or set_gapcolor, so gapcolor doesn't work in plotting methods that return LineCollections (like vlines or hlines).
Code for reproduction
fig, ax = plt.subplots(figsize=(1,1))
ax.vlines([.25, .75], 0, 1, linestyle=':', gapcolor='orange')Actual outcome
File ~\miniconda3\envs\prop\lib\site-packages\matplotlib\artist.py:1186, in Artist._internal_update(self, kwargs)
-> 1186 return self._update_props(
1187 kwargs, "{cls.__name__}.set() got an unexpected keyword argument "
1188 "{prop_name!r}")
AttributeError: LineCollection.set() got an unexpected keyword argument 'gapcolor'Expected outcome
Additional information
I think the easiest fix is probably add set_color and get_color to LineCollection, modeled on get_color and set_color
matplotlib/lib/matplotlib/collections.py
Lines 1463 to 1481 in 5093150
Matplotlib Version
3.7.0.dev1121+g509315008c
Activity
rcomer commented on Dec 23, 2022
I had a look at this. Although the LineCollection docstring states that it “Represents a sequence of Line2Ds”, it doesn’t seem to use the Line2D object (unless I’m missing something).
So I think we might need to modify the Collection.draw method in an analogous way to how we did the Line2D.draw method at #23208. Though Collection.draw is more complicated as it’s obviously supporting a much wider range of cases.
Another possibility might be to modify LineCollection itself so that, if gapgolor is set, we add the inverse paths into LineCollection._paths (and update._edgecolors, ._linestyles with gapcolors and inverse linestyles). This would mean that what you get out of e.g. .get_colors would be longer than what was put into .set_colors, which might not be desirable.
Anyway, for now I just mark this as “medium difficulty”, as I do not think it is a task for a beginner.