René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Passing an incorrectly sized colour list to scatter should raise a relevant error","articleBody":"### Bug report\r\n\r\n**Bug summary**\r\n\r\nWhen calling a `scatter` with a list for the `c` argument, which does not match the length of the data, an `AttributeError: 'list' object has no attribute 'shape'` is raised instead of informing the user about the non-matching length issue. \r\n\r\n#7363 tried hard to make error message clearer but forgot to consider that input may be any sequence, not necessarily a numpy array.  \r\nA similar issue was raised in #9209.\r\n\r\n**Code for reproduction**\r\n\r\n``` \r\nimport matplotlib.pyplot as plt\r\nx = [1,2,3,4,5]\r\nc = [1,2,3,4,5,6] # one color more than values\r\nplt.scatter(x,x, c=c)\r\nplt.show()\r\n\r\n```\r\n\r\n**Actual outcome**\r\n\r\n\u003c!--The output produced by the above code, which may be a screenshot, console output, etc.--\u003e\r\nAn error\r\n```\r\nFile \"...\\lib\\site-packages\\matplotlib\\axes\\_axes.py\", line 4279, in scatter\r\n    .format(c.shape, x.size, y.size))\r\n\r\nAttributeError: 'list' object has no attribute 'shape'\r\n```\r\nThis error tells nothing about the true cause of the problem, but is rather an error caused by the error message itself.\r\n\r\n\r\n**Expected outcome**\r\n\r\nAn error similar to the intended one\r\n\r\nhttps://github.com/matplotlib/matplotlib/blob/6ec80eac66c4828f28540f76734cae811787d626/lib/matplotlib/axes/_axes.py#L3946-L3950\r\n\r\nbut for a list, which does not have a `shape` attribute.\r\n\r\nNote that I rather raised this issue, instead of directly fixing it, because I'm not sure if there should be some typechecking performed within the `except` clause or whether to add another `try` inside the `except` or - because both feels kind of strange - someone has an even better idea. \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: Windows 8.1\r\n  * Matplotlib version: 2.2.2\r\n  * Matplotlib backend: any\r\n  * Python version: 3.6\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\n","author":{"url":"https://github.com/ImportanceOfBeingErnest","@type":"Person","name":"ImportanceOfBeingErnest"},"datePublished":"2018-06-04T21:07:19.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/11373/matplotlib/issues/11373"}