René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Removal of y-shared polar axes causes crash at draw time","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\nAll's in the title.\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\nfrom pylab import *\r\nax1, ax2 = gcf().subplots(2, sharey=True, subplot_kw={\"projection\": \"polar\"}); ax2.remove(); show()\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\nTraceback (most recent call last):\r\n  File \".../path/to/matplotlib/backends/backend_qt5.py\", line 440, in _draw_idle\r\n    self.draw()\r\n  File \"/home/antony/src/local/mplcairo/lib/mplcairo/base.py\", line 269, in draw\r\n    self.get_renderer(_ensure_cleared=True, _ensure_drawn=True)\r\n  File \"/home/antony/src/local/mplcairo/lib/mplcairo/base.py\", line 261, in get_renderer\r\n    return self._get_cached_or_new_renderer(\r\n  File \"/home/antony/src/local/mplcairo/lib/mplcairo/base.py\", line 256, in _get_cached_or_new_renderer\r\n    self.figure.draw(renderer)\r\n  File \".../path/to/matplotlib/artist.py\", line 74, in draw_wrapper\r\n    result = draw(artist, renderer, *args, **kwargs)\r\n  File \".../path/to/matplotlib/artist.py\", line 51, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \".../path/to/matplotlib/figure.py\", line 2730, in draw\r\n    mimage._draw_list_compositing_images(\r\n  File \".../path/to/matplotlib/image.py\", line 132, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \".../path/to/matplotlib/_api/deprecation.py\", line 447, in wrapper\r\n    return func(*inner_args, **inner_kwargs)\r\n  File \".../path/to/matplotlib/_api/deprecation.py\", line 447, in wrapper\r\n    return func(*inner_args, **inner_kwargs)\r\n  File \".../path/to/matplotlib/projections/polar.py\", line 994, in draw\r\n    super().draw(renderer, *args, **kwargs)\r\n  File \".../path/to/matplotlib/artist.py\", line 51, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \".../path/to/matplotlib/_api/deprecation.py\", line 421, in wrapper\r\n    return func(*inner_args, **inner_kwargs)\r\n  File \".../path/to/matplotlib/axes/_base.py\", line 3102, in draw\r\n    mimage._draw_list_compositing_images(renderer, self, artists)\r\n  File \".../path/to/matplotlib/image.py\", line 132, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \".../path/to/matplotlib/artist.py\", line 51, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \".../path/to/matplotlib/axis.py\", line 1124, in draw\r\n    ticks_to_draw = self._update_ticks()\r\n  File \".../path/to/matplotlib/axis.py\", line 1011, in _update_ticks\r\n    major_locs = self.get_majorticklocs()\r\n  File \".../path/to/matplotlib/axis.py\", line 1243, in get_majorticklocs\r\n    return self.major.locator()\r\n  File \".../path/to/matplotlib/projections/polar.py\", line 432, in __call__\r\n    return [tick for tick in self.base() if tick \u003e rorigin]\r\n  File \".../path/to/matplotlib/projections/polar.py\", line 432, in __call__\r\n    return [tick for tick in self.base() if tick \u003e rorigin]\r\n  File \".../path/to/matplotlib/ticker.py\", line 2265, in __call__\r\n    return self.tick_values(vmin, vmax)\r\n  File \".../path/to/matplotlib/ticker.py\", line 2273, in tick_values\r\n    locs = self._raw_ticks(vmin, vmax)\r\n  File \".../path/to/matplotlib/ticker.py\", line 2212, in _raw_ticks\r\n    nbins = np.clip(self.axis.get_tick_space(),\r\n  File \".../path/to/matplotlib/axis.py\", line 2513, in get_tick_space\r\n    length = ((ends[1][1] - ends[0][1]) / self.axes.figure.dpi) * 72\r\nAttributeError: 'NoneType' object has no attribute 'dpi'\r\n```\r\n\r\n**Expected outcome**\r\n\r\nNormal axes removal.\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: linux\r\n  * Matplotlib version (`import matplotlib; print(matplotlib.__version__)`): head\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): mplcairo\r\n  * Python version: 39\r\n  * Jupyter version (if applicable): \r\n  * Other libraries: \r\n\r\n(Note that this is a separate issue from https://github.com/matplotlib/matplotlib/issues/19988 as the root cause seems very different.)\r\n\r\nEdit: I have a fix, but the test is a bit simpler if https://github.com/matplotlib/matplotlib/pull/19994 goes in first.","author":{"url":"https://github.com/anntzer","@type":"Person","name":"anntzer"},"datePublished":"2021-04-16T16:50:07.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/19989/matplotlib/issues/19989"}