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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Misleading error message in _parse_scatter_color_args","articleBody":"\u003c!--To help us understand and resolve your issue, please fill out the form to the best of your ability.--\u003e\r\n\u003c!--You can feel free to delete the sections that do not apply.--\u003e\r\n\r\n### Bug report\r\n\r\nNot really a bug, just an annoying error message. \r\nIn `_axes.py`, line 4283, the `try` clause catches errors in an unintended section of code and adds an error message that doesn't make sense to the traceback. For instance, if a `ValueError` is raised in the call to `to_rgb_array(c)`, it will be caught and the error would be wrong. \r\n\r\n\u003c!--A short 1-2 sentences that succinctly describes the bug--\u003e\r\n\r\nCode for reproduction:\r\n\r\n\u003c!--A minimum code snippet required to reproduce the bug.\r\nPlease make sure to minimize the number of dependencies required, and provide\r\nany necessary plotted data.\r\nAvoid using threads, as Matplotlib is (explicitly) not thread-safe.--\u003e\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\na = np.arange(10)\r\nb = np.random.rand(10)\r\ncolors = np.random.rand(10, 3) * 2.0\r\n\r\nplt.scatter(a, b, c=colors)\r\n```\r\n\r\nThis results in the following traceback:\r\n\r\n\u003c!--The output produced by the above code, which may be a screenshot, console output, etc.--\u003e\r\n\r\n```\r\nTraceback (most recent call last):\r\n  File \"/Users/user/lib/python3.6/site-packages/matplotlib/axes/_axes.py\", line 4284, in _parse_scatter_color_args\r\n    colors = mcolors.to_rgba_array(c)\r\n  File \"/Users/user/lib/python3.6/site-packages/matplotlib/colors.py\", line 279, in to_rgba_array\r\n    raise ValueError(\"RGBA values should be within 0-1 range\")\r\nValueError: RGBA values should be within 0-1 range\r\n\r\nDuring handling of the above exception, another exception occurred:\r\n\r\nTraceback (most recent call last):\r\n  File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\r\n  File \"/Users/user/lib/python3.6/site-packages/matplotlib/pyplot.py\", line 2841, in scatter\r\n    None else {}), **kwargs)\r\n  File \"/Users/user/lib/python3.6/site-packages/matplotlib/__init__.py\", line 1599, in inner\r\n    return func(ax, *map(sanitize_sequence, args), **kwargs)\r\n  File \"/Users/user/lib/python3.6/site-packages/matplotlib/axes/_axes.py\", line 4453, in scatter\r\n    get_next_color_func=self._get_patches_for_fill.get_next_color)\r\n  File \"/Users/user/lib/python3.6/site-packages/matplotlib/axes/_axes.py\", line 4297, in _parse_scatter_color_args\r\n    .format(nc=n_elem, xs=xsize, ys=ysize)\r\nValueError: 'c' argument has 10 elements, which is not acceptable for use with 'x' with size 10, 'y' with size 10.\r\n```\r\n\r\nThe first part of the traceback makes sense, but the last error message shouldn't be there, especially since it states something that is not true (number of elements is acceptable). \r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system: MacOS 10.15.3\r\n  * Matplotlib version: 3.1.2\r\n  * Matplotlib backend: MacOSX\r\n  * Python version: 3.6.8\r\n \r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\nThanks!","author":{"url":"https://github.com/orrkrup","@type":"Person","name":"orrkrup"},"datePublished":"2020-04-25T09:18:09.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/17243/matplotlib/issues/17243"}