René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: matplotlib.colors.LinearSegmentedColormap.from_list doesn't work with hex representation of colors","articleBody":"### Bug summary\n\nFor some reason colors.LinearSegmentedColormap.from_list stopped working with colors such as '#E3DBCC', when in previous versions it used to work. \r\n\r\nIt raises an error in `to_rgba_array(colors)`, but  when actually calling `colors.to_rgba_array(['#E3DBCC'])` it works just fine.\n\n### Code for reproduction\n\n```python\nimport matplotlib.colors as colors\r\nstart = '#E3DBCC'\r\nend = '#FF4B33'\r\n\r\ncolor_list = [(0, start), (1, end)]\r\nmy_cmap = colors.LinearSegmentedColormap.from_list('my_cmap', color_list)\n```\n\n\n### Actual outcome\n\n```\r\n---------------------------------------------------------------------------\r\nValueError                                Traceback (most recent call last)\r\nCell In[12], line 6\r\n      3 end = '#FF4B33'\r\n      5 color_list = [(0, start), (1, end)]\r\n----\u003e 6 my_cmap = colors.LinearSegmentedColormap.from_list('my_cmap', color_list)\r\n\r\nFile ~/mambaforge/envs/tf/lib/python3.9/site-packages/matplotlib/colors.py:1065, in LinearSegmentedColormap.from_list(name, colors, N, gamma)\r\n   1062 else:\r\n   1063     vals = np.linspace(0, 1, len(colors))\r\n-\u003e 1065 r, g, b, a = to_rgba_array(colors).T\r\n   1066 cdict = {\r\n   1067     \"red\": np.column_stack([vals, r, r]),\r\n   1068     \"green\": np.column_stack([vals, g, g]),\r\n   1069     \"blue\": np.column_stack([vals, b, b]),\r\n   1070     \"alpha\": np.column_stack([vals, a, a]),\r\n   1071 }\r\n   1073 return LinearSegmentedColormap(name, cdict, N, gamma)\r\n\r\nFile ~/mambaforge/envs/tf/lib/python3.9/site-packages/matplotlib/colors.py:489, in to_rgba_array(c, alpha)\r\n    487         raise e\r\n    488 if isinstance(c, str):\r\n--\u003e 489     raise ValueError(f\"{c!r} is not a valid color value.\")\r\n    491 if len(c) == 0:\r\n    492     return np.zeros((0, 4), float)\r\n\r\nValueError: '#E3DBCC' is not a valid color value.\r\n```\n\n### Expected outcome\n\nI expect the LinearSegmentedColormap to be created successfully. \n\n### Additional information\n\n_No response_\n\n### Operating system\n\nOS X 13.1\n\n### Matplotlib Version\n\n3.8.0\n\n### Matplotlib Backend\n\n'module://matplotlib_inline.backend_inline'\n\n### Python version\n\n3.9\n\n### Jupyter version\n\n3.6.1\n\n### Installation\n\nconda","author":{"url":"https://github.com/jose-vines-toteat","@type":"Person","name":"jose-vines-toteat"},"datePublished":"2023-10-08T02:27:18.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/27029/matplotlib/issues/27029"}