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BUG: matplotlib 3.4.0 -- Scatter with colormap and legend gives TypeError: object of type 'NoneType' has no len() #19779
Description
Activity
A bisect diagnose shows that the problem was introduced in the commit
4c3d644 (#18480), which changed the way Collections deal with color.A quick fix is easy, but I don't have much in-depth understanding of this part of the code. If anyone familiar with this part can have a discussion, that would be great. Or I just open a PR for discussion.
Opening a PR is probably the best way forward 👍
Reacted by Thomas A CaswellA bisect diagnose shows that the problem was introduced in the commit
4c3d644 (#18480), which changed the way Collections deal with color.A quick fix is easy, but I don't have much in-depth understanding of this part of the code. If anyone is familiar with this part can have a discussion, that would be great. Or I just open a PR for discussion.
Actually, this problem has been solved in the commit ed6d92b (#19552), but this commit was not included in v3.4.x branch. Backport that commit will solve this problem.
That commit removes API and cannot be included in v3.4.x directly.
- added a commit that references this issue on Mar 29, 2021
- added a commit that references this issue on Mar 30, 2021
- added a commit that references this issue on Mar 30, 2021
Thanks for the quick fix!
Bug report
Bug summary
With matplotlib 3.4.0, scatter plot with colormap and legend gives TypeError: object of type 'NoneType' has no len().
Code for reproduction
Actual outcome
Traceback (most recent call last): File ".../matplotlib/backends/backend_qt5.py", line 475, in _draw_idle self.draw() File ".../matplotlib/backends/backend_agg.py", line 406, in draw self.figure.draw(self.renderer) File ".../matplotlib/artist.py", line 74, in draw_wrapper result = draw(artist, renderer, *args, **kwargs) File ".../matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer, *args, **kwargs) File ".../matplotlib/figure.py", line 2734, in draw mimage._draw_list_compositing_images( File ".../matplotlib/image.py", line 132, in _draw_list_compositing_images a.draw(renderer) File ".../matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer, *args, **kwargs) File ".../matplotlib/_api/deprecation.py", line 431, in wrapper return func(*inner_args, **inner_kwargs) File ".../matplotlib/axes/_base.py", line 2925, in draw mimage._draw_list_compositing_images(renderer, self, artists) File ".../matplotlib/image.py", line 132, in _draw_list_compositing_images a.draw(renderer) File ".../matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer, *args, **kwargs) File ".../matplotlib/legend.py", line 614, in draw self._legend_box.draw(renderer) File ".../matplotlib/offsetbox.py", line 368, in draw c.draw(renderer) File ".../matplotlib/offsetbox.py", line 368, in draw c.draw(renderer) File ".../matplotlib/offsetbox.py", line 368, in draw c.draw(renderer) [Previous line repeated 1 more time] File ".../matplotlib/offsetbox.py", line 694, in draw c.draw(renderer) File ".../matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer, *args, **kwargs) File ".../matplotlib/collections.py", line 1009, in draw super().draw(renderer) File ".../matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer, *args, **kwargs) File ".../matplotlib/collections.py", line 380, in draw len(facecolors) == 1 and len(edgecolors) == 1 and TypeError: object of type 'NoneType' has no len()Expected outcome
With matplotlib 3.3.4, I get this (no warning or error):
Matplotlib version