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[Bug]: Args for tripcolor #22303
Description
Bug summary
Thanks for matplotlib!
tripcolor fails if colors are passed with named argument i.e c=values instead of just values. The error is not very informative and it seems a dangerous practice to ignore kwargs and only use args.
File "/mnt/session_space/conda_envs/latest39/lib/python3.9/site-packages/matplotlib/tri/tripcolor.py", line 57, in tripcolor
C = np.asarray(args[0])
IndexError: list index out of rangeCode for reproduction
plt.tripcolor(vertices[:,0], vertices[:,1], c=values, triangles=triangles)Actual outcome
File "/mnt/session_space/conda_envs/latest39/lib/python3.9/site-packages/matplotlib/tri/tripcolor.py", line 57, in tripcolor
C = np.asarray(args[0])
IndexError: list index out of rangeExpected outcome
a successful plot.
Additional information
No response
Operating system
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Matplotlib Version
3.5.1
Matplotlib Backend
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Python version
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Jupyter version
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Installation
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Activity
QuLogic commentedon Jan 25, 2022
Please provide a complete example. (Also, I don't think
cis a valid keyword argument totripcolor.)jklymak commentedon Jan 28, 2022
I'll close for lack of response, but do request a re-open if there is still an issue here.
anntzer commentedon Jan 28, 2022
Basically
tripcolor(np.random.rand(5), np.random.rand(5), C=np.random.rand(5))currently fails with the not-so-informative error message above (the correct invocation istripcolor(np.random.rand(5), np.random.rand(5), np.random.rand(5))). I think we should indeed not allow passing C by keyword, only positionally (see #11526 for essentially the same discussion on quiver); however the error could be made clearer.timhoffm commentedon Jan 28, 2022
Unfortunately, the API is heavily overloaded. We need an
*argsparameter that can take many forms, and we cannot get rid of it without major API breakage. Things to do:triangulation, C, kwargs = parse_params(args, kwargs)that we can unittest the defined API against, and that issues reasonable warnings.