Improve error message for incorrect color string #22665
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QuLogic
reviewed
Mar 18, 2022
timhoffm
reviewed
Mar 18, 2022
lib/matplotlib/colors.py
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| if len(c): | ||
| raise ValueError("Using a string of single character colors as " | ||
| "a color sequence is not supported. The colors " | ||
| "can be passed as an explicit list instead.") | ||
| else: | ||
| raise ValueError("Using an empty string for color is not " | ||
| "supported. Use 'none' if you do not want any " | ||
| "color.") |
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"string of single characters" was deprecated in 3.2 and removed in 3.4 (#18069). IMHO we don't need to bother users with that anymore - It's even more likely nowadays that they have just made a typo like 'yellwo'.
We should at least change the first message to raise ValueError(f"{c!r} is not a valid color value")
I even argue that the empty distinction is not necessary. We don't do this in other parts of the code either (c.f. plt.plot([0], color=''). I'd just go for
Suggested change
| if len(c): | |
| raise ValueError("Using a string of single character colors as " | |
| "a color sequence is not supported. The colors " | |
| "can be passed as an explicit list instead.") | |
| else: | |
| raise ValueError("Using an empty string for color is not " | |
| "supported. Use 'none' if you do not want any " | |
| "color.") | |
| raise ValueError(f"{c!r} is not a valid color value") |
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timhoffm
approved these changes
Mar 22, 2022
tacaswell
reviewed
Mar 23, 2022
tacaswell
approved these changes
Mar 23, 2022
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PR Summary
Closes #22662
The error message when supplying an empty string for color was a bit confusing:
Now a dedicated version is used for the empty string:
PR Checklist
Tests and Styling
pytestpasses).flake8-docstringsand runflake8 --docstring-convention=all).Documentation
doc/users/next_whats_new/(follow instructions in README.rst there).doc/api/next_api_changes/(follow instructions in README.rst there).