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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: colors.LinearSegmentedColormap.from_list does not take two tuples in 3.8.0","articleBody":"### Bug summary\r\n\r\nIncrementing from v3.7 to v3.8 the option to specify a start and end value is no longer functioning when two values are specified.  It still works when three are specified.\r\n\r\n``` \r\n## This works:\r\nmatplotlib.colors.LinearSegmentedColormap.from_list(\"myMap\", [\"#000000\", \"#FFFFFF\"])\r\n```\r\n\r\n``` \r\n## This does not:\r\nmatplotlib.colors.LinearSegmentedColormap.from_list(\"myMap\", [(0,\"#000000\"), (1,\"#FFFFFF\")])\r\n```\r\n\r\n\r\n### Code for reproduction\r\n\r\n```python\r\nmatplotlib.colors.LinearSegmentedColormap.from_list(\"myMap\", [(0,\"#000000\"), (1,\"#FFFFFF\")])\r\n```\r\n\r\n\r\n### Actual outcome\r\n\r\nTraceback (most recent call last):\r\n  File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\r\n  File \"/Users/dave/.local/share/virtualenvs/projects-t0xU6-ce/lib/python3.10/site-packages/matplotlib/colors.py\", line 1065, in from_list\r\n    colors : array-like of colors or array-like of (value, color)\r\n  File \"/Users/dave/.local/share/virtualenvs/projects-t0xU6-ce/lib/python3.10/site-packages/matplotlib/colors.py\", line 489, in to_rgba_array\r\n    pass\r\nValueError: '#000000' is not a valid color value.\r\n\r\n### Expected outcome\r\n\r\n\u003cmatplotlib.colors.LinearSegmentedColormap object at 0x101e7f520\u003e\r\n\r\n### Additional information\r\n\r\nWorked in 3.7\r\n\r\nThe issue I think is related to zipped values being passed to `r, g, b, a = to_rgba_array(colors).T`.  A tuple gets passed in rather than a list.\r\n\r\n```\r\n## tuple len 2 fails\r\n\u003e\u003e\u003e matplotlib.colors.to_rgba_array((\"#000000\", \"#FFFFFF\"))\r\nTraceback (most recent call last):\r\n  File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\r\n  File \"/Users/dave/.local/share/virtualenvs/model_train-t0xU6-ce/lib/python3.10/site-packages/matplotlib/colors.py\", line 489, in to_rgba_array\r\n    pass\r\nValueError: '#000000' is not a valid color value.\r\n## list works\r\n\u003e\u003e\u003e matplotlib.colors.to_rgba_array([\"#000000\", \"#FFFFFF\"])\r\narray([[0., 0., 0., 1.],\r\n       [1., 1., 1., 1.]])\r\n```\r\n\r\nChanging `r, g, b, a = to_rgba_array(colors).T` in `colors.py:LinearSegmentedColormap.from_list` to `r, g, b, a = to_rgba_array(list(colors)).T`  or similar may fix.\r\n\r\n\r\n### Operating system\r\n\r\nOS/X\r\n\r\n### Matplotlib Version\r\n\r\n3.8.0\r\n\r\n### Matplotlib Backend\r\n\r\nMacOSX\r\n\r\n### Python version\r\n\r\nPython 3.10.9\r\n\r\n### Jupyter version\r\n\r\n_No response_\r\n\r\n### Installation\r\n\r\nNone","author":{"url":"https://github.com/dave-shirley-faraday","@type":"Person","name":"dave-shirley-faraday"},"datePublished":"2023-09-28T16:59:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/26949/matplotlib/issues/26949"}