René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Can no longer deepcopy LogNorm objects on master","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\nAs of 0d1d95c8b4a00bfdbb0b7f02a4a0152f6fe57dcb on the master branch it is no longer possible to deepcopy a `LogNorm` instance, which is a regression from `3.3.x`.\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.colors as mcolor\r\nimport copy\r\nnorm = mcolor.LogNorm()\r\ncopy.deepcopy(norm)\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```\r\nTraceback (most recent call last):\r\n  File \"test.py\", line 4, in \u003cmodule\u003e\r\n    copy.deepcopy(norm)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 172, in deepcopy\r\n    y = _reconstruct(x, memo, *rv)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 270, in _reconstruct\r\n    state = deepcopy(state, memo)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 146, in deepcopy\r\n    y = copier(x, memo)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 230, in _deepcopy_dict\r\n    y[deepcopy(key, memo)] = deepcopy(value, memo)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 172, in deepcopy\r\n    y = _reconstruct(x, memo, *rv)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 270, in _reconstruct\r\n    state = deepcopy(state, memo)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 146, in deepcopy\r\n    y = copier(x, memo)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 230, in _deepcopy_dict\r\n    y[deepcopy(key, memo)] = deepcopy(value, memo)\r\n  File \"/Users/dstansby/miniconda3/envs/dev/lib/python3.8/copy.py\", line 153, in deepcopy\r\n    y = copier(memo)\r\n  File \"/Users/dstansby/github/matplotlib/lib/matplotlib/transforms.py\", line 143, in __copy__\r\n    raise NotImplementedError(\r\nNotImplementedError: TransformNode instances can not be copied. Consider using frozen() instead.\r\n```\r\n\r\n**Expected outcome**\r\n\r\nNo error\r\n\u003c!--A description of the expected outcome from the code snippet--\u003e\r\n\u003c!--If this used to work in an earlier version of Matplotlib, please note the version it used to work on--\u003e\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:\r\n  * Matplotlib version: \r\n  * Matplotlib backend (`print(matplotlib.get_backend())`):\r\n  * Python version:\r\n  * Jupyter version (if applicable):\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\n","author":{"url":"https://github.com/dstansby","@type":"Person","name":"dstansby"},"datePublished":"2020-07-29T16:17:28.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":15},"url":"https://github.com/18119/matplotlib/issues/18119"}