René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Setting norm with existing colorbar fails with 3.6.3","articleBody":"### Bug summary\r\n\r\nSetting the norm to a `LogNorm` after the colorbar has been created (e.g. in interactive code) fails with an `Invalid vmin` value in matplotlib 3.6.3.\r\n\r\nThe same code worked in previous matplotlib versions.\r\n\r\nNot that vmin and vmax are explicitly set to values valid for `LogNorm` and no negative values (or values == 0) exist in the input data.\r\n\r\n### Code for reproduction\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\nfrom matplotlib.colors import LogNorm\r\nimport numpy as np\r\n\r\n# create some random data to fill a 2d plot\r\nrng = np.random.default_rng(0)\r\nimg = rng.uniform(1, 5, (25, 25))\r\n\r\n# plot it\r\nfig, ax = plt.subplots(layout=\"constrained\")\r\nplot = ax.pcolormesh(img)\r\ncbar = fig.colorbar(plot, ax=ax)\r\n\r\nvmin = 1\r\nvmax = 5\r\n\r\nplt.ion()\r\nfig.show()\r\nplt.pause(0.5)\r\n\r\nplot.norm = LogNorm(vmin, vmax)\r\nplot.autoscale()\r\nplt.pause(0.5)\r\n```\r\n\r\n\r\n### Actual outcome\r\n\r\n```\r\nTraceback (most recent call last):\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/backends/backend_qt.py\", line 454, in _draw_idle\r\n    self.draw()\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/backends/backend_agg.py\", line 405, in draw\r\n    self.figure.draw(self.renderer)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/artist.py\", line 74, in draw_wrapper\r\n    result = draw(artist, renderer, *args, **kwargs)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/artist.py\", line 51, in draw_wrapper\r\n    return draw(artist, renderer)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/figure.py\", line 3082, in draw\r\n    mimage._draw_list_compositing_images(\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/image.py\", line 131, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/artist.py\", line 51, in draw_wrapper\r\n    return draw(artist, renderer)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/axes/_base.py\", line 3100, in draw\r\n    mimage._draw_list_compositing_images(\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/image.py\", line 131, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/artist.py\", line 51, in draw_wrapper\r\n    return draw(artist, renderer)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/collections.py\", line 2148, in draw\r\n    self.update_scalarmappable()\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/collections.py\", line 891, in update_scalarmappable\r\n    self._mapped_colors = self.to_rgba(self._A, self._alpha)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/cm.py\", line 511, in to_rgba\r\n    x = self.norm(x)\r\n  File \"/home/mnoethe/.local/conda/envs/cta-dev/lib/python3.9/site-packages/matplotlib/colors.py\", line 1694, in __call__\r\n    raise ValueError(\"Invalid vmin or vmax\")\r\nValueError: Invalid vmin or vmax\r\n```\r\n\r\n### Expected outcome\r\n\r\nWorks, colorbar and mappable are updated with new norm.\r\n\r\n### Additional information\r\n\r\n_No response_\r\n\r\n### Operating system\r\n\r\nLinux\r\n\r\n### Matplotlib Version\r\n\r\n3.6.3 (works with 3.6.2)\r\n\r\n### Matplotlib Backend\r\n\r\nMultpiple backends tested, same error in all (Qt5Agg, TkAgg, agg, ...)\r\n\r\n### Python version\r\n\r\n3.9.15\r\n\r\n### Jupyter version\r\n\r\nnot in jupyter\r\n\r\n### Installation\r\n\r\nconda","author":{"url":"https://github.com/maxnoe","@type":"Person","name":"maxnoe"},"datePublished":"2023-01-25T10:01:49.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/25077/matplotlib/issues/25077"}