René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: `matplotlib.pyplot.scatter` does not respect mask rules with `datetime`","articleBody":"### Bug summary\r\n\r\nPlotting a numpy masked array against a list of datetime objects, `plt.plot` functions as expected, but `plt.scatter` still displays the masked data. Auto-axis limits *do* respect the masked data though.\r\n\r\n### Code for reproduction\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\nimport numpy.ma as ma\r\nfrom datetime import datetime\r\n\r\n# Create a list of datetime objects\r\ntime_unmasked = [datetime(2022, 11, 24, 4, 49, 52),\r\n                 datetime(2022, 11, 24, 4, 49, 53),\r\n                 datetime(2022, 11, 24, 4, 49, 54),\r\n                 datetime(2022, 11, 24, 4, 49, 55),\r\n                 datetime(2022, 11, 24, 4, 49, 56),\r\n                 datetime(2022, 11, 24, 4, 49, 57),\r\n                 datetime(2022, 11, 24, 4, 49, 58)]\r\n\r\n# Create a masked array with three masked variables, one datapoint far from others\r\ndata_masked = ma.array([15,14,50,15,15,15,16], mask=[0,0,1,1,1,0,0])\r\n\r\n# Line plot (expected behaviour)\r\nplt.plot(time_unmasked, data_masked)\r\nplt.show()\r\n\r\n# Scatter plot (plots masked points, but ignores masked values when auto-setting axis limits)\r\nplt.scatter(time_unmasked, data_masked)\r\nplt.show()\r\n```\r\n\r\n\r\n### Actual outcome\r\n\r\n`plot` behaves as expected.\r\n\r\n[![enter image description here][1]][1]\r\n\r\n`scatter` unexpectedly draws the masked datapoints, but axes limits are still respecting the masked array as the masked `y=50` value is not visible.\r\n[![enter image description here][2]][2]\r\n\r\n\r\n\r\n  [1]: https://i.stack.imgur.com/wk1FI.png\r\n  [2]: https://i.stack.imgur.com/6Y6S1.png\r\n\r\n\r\n### Expected outcome\r\n\r\nScatter should not plot the masked data even though all timestamps are unmasked.\r\n[![enter image description here][3]][3]\r\n\r\n\r\n  [3]: https://i.stack.imgur.com/necjd.png\r\n\r\n### Additional information\r\n\r\nIt seems as though there is a check within `matplotlib.pyplot.scatter` that is not catching. I'd expect that logic to check that if either `x` or `y` were masked, to not plot that point. The datetime object is able to slip through. I've also tried putting `time_unmasked` within a numpy masked array with the same mask as `masked_data` (so both `x` and `y` have the same mask), but the same unexpected behaviour occurs.\r\n\r\n### Operating system\r\n\r\nMacOS 11.3.1 (20E241)\r\n\r\n### Matplotlib Version\r\n\r\n3.5.3\r\n\r\n### Matplotlib Backend\r\n\r\nmodule://ipykernel.pylab.backend_inline\r\n\r\n### Python version\r\n\r\n3.8.11\r\n\r\n### Jupyter version\r\n\r\n5.7.10\r\n\r\n### Installation\r\n\r\nconda","author":{"url":"https://github.com/Benblob688","@type":"Person","name":"Benblob688"},"datePublished":"2022-11-25T11:28:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/24545/matplotlib/issues/24545"}