René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Regression in 3.4.0rc1 in creating ListedColormap from a set","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\n**Bug summary**\r\n\r\nApparently I have some code that creates a `ListedColormap` object from a set of RGB tuples (I'm not sure why) and this fails on the 3.4.0 release candidate, but didn't previously.\r\n\r\n**Code 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 as mpl\r\nprint(mpl.__version__)\r\ncolors = [(0, .5, 1), (1, .2, .5), (.4, 1, .2)]\r\ncmap = mpl.colors.ListedColormap(set(colors))\r\nprint(cmap([0, .5, 1]))\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\n\r\n```python-traceback\r\n3.4.0rc1\r\nTraceback (most recent call last):\r\n  File \"mpl_debug.py\", line 5, in \u003cmodule\u003e\r\n    print(cmap([0, .5, 1]))\r\n  File \"/Users/mwaskom/miniconda3/envs/mpl34_test/lib/python3.8/site-packages/matplotlib/colors.py\", line 598, in __call__\r\n    self._init()\r\n  File \"/Users/mwaskom/miniconda3/envs/mpl34_test/lib/python3.8/site-packages/matplotlib/colors.py\", line 1036, in _init\r\n    self._lut[:-3] = to_rgba_array(self.colors)\r\n  File \"/Users/mwaskom/miniconda3/envs/mpl34_test/lib/python3.8/site-packages/matplotlib/colors.py\", line 369, in to_rgba_array\r\n    rgba = np.column_stack([c, np.ones(len(c))])\r\n  File \"\u003c__array_function__ internals\u003e\", line 5, in column_stack\r\n  File \"/Users/mwaskom/miniconda3/envs/mpl34_test/lib/python3.8/site-packages/numpy/lib/shape_base.py\", line 656, in column_stack\r\n    return _nx.concatenate(arrays, 1)\r\n  File \"\u003c__array_function__ internals\u003e\", line 5, in concatenate\r\nValueError: all the input array dimensions for the concatenation axis must match exactly, but along dimension 0, the array at index 0 has size 1 and the array at index 1 has size 3\r\n```\r\n\r\n**Expected outcome**\r\n\r\n```\r\n3.3.2\r\n[[1.  0.2 0.5 1. ]\r\n [0.4 1.  0.2 1. ]\r\n [0.  0.5 1.  1. ]]\r\n```\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\r\n  * Matplotlib version (`import matplotlib; print(matplotlib.__version__)`):  3.4.0.rc1\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`):  macosx\r\n  * Python version: 3.8.x\r\n  * Jupyter version (if applicable): na\r\n  * Other libraries: \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\nInstalled the release candidate by pointing pip at the tarball on the github releases page.\r\n","author":{"url":"https://github.com/mwaskom","@type":"Person","name":"mwaskom"},"datePublished":"2021-02-19T13:06:30.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":21},"url":"https://github.com/19544/matplotlib/issues/19544"}