René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Removing a shared axes via `ax.remove()` leads to an error.","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\nremoving a shared axes via `ax.remove()` leads to an error.\r\n\r\nThis bisects to \"Fix locator/formatter setting when removing shared Axes\" #13983 (in current master, targeted for 3.2) which initially headed out to make the situation of removing a shared axes better, fixing https://github.com/matplotlib/matplotlib/issues/12853, but apparently the test doesn't capture the below simple case.\r\n\r\nHence marking as release critical for 3.2, in order not to release this bug.\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.pyplot as plt\r\n\r\nfig, axs = plt.subplots(2, sharex=True)\r\n\r\naxs[0].remove()\r\n\r\nplt.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\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\backends\\backend_qt5.py\", line 488, in _draw_idle\r\n    self.draw()\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\backends\\backend_agg.py\", line 396, in draw\r\n    self.figure.draw(self.renderer)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\figure.py\", line 1722, in draw\r\n    renderer, self, artists, self.suppressComposite)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\image.py\", line 136, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\axes\\_base.py\", line 2622, in draw\r\n    mimage._draw_list_compositing_images(renderer, self, artists)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\image.py\", line 136, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\axis.py\", line 1227, in draw\r\n    ticks_to_draw = self._update_ticks()\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\axis.py\", line 1103, in _update_ticks\r\n    major_locs = self.get_majorticklocs()\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\axis.py\", line 1348, in get_majorticklocs\r\n    return self.major.locator()\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\ticker.py\", line 2032, in __call__\r\n    return self.tick_values(vmin, vmax)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\ticker.py\", line 2040, in tick_values\r\n    locs = self._raw_ticks(vmin, vmax)\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\ticker.py\", line 1979, in _raw_ticks\r\n    nbins = np.clip(self.axis.get_tick_space(),\r\n  File \"d:\\***\\matplotlib\\lib\\matplotlib\\axis.py\", line 2193, in get_tick_space\r\n    length = ((ends[1][0] - ends[0][0]) / self.axes.figure.dpi) * 72\r\nAttributeError: 'NoneType' object has no attribute 'dpi'\r\n```\r\n\r\n**Expected outcome**\r\n\r\nA plot with the first axes removed, as would be achieved with the same code running in 3.1\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: Win 8.1\r\n  * Matplotlib version: current master\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): Qt5Agg\r\n  * Python version: 3.6\r\n\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/ImportanceOfBeingErnest","@type":"Person","name":"ImportanceOfBeingErnest"},"datePublished":"2019-07-29T02:31:56.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/14911/matplotlib/issues/14911"}