René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Crash when Removing Suptitle in a Figure with Constrained Layout","articleBody":"### Bug summary\n\nThe renderer crashes after adding a suptitle and removing it in a figure with constrained layout. The plot is expected to remain the same after performing the insertion and removal of the suptitle.\n\n### Code for reproduction\n\n```Python\nimport matplotlib\nprint(matplotlib.__version__)  # 3.10.8\nimport matplotlib.pyplot as plt\ndef remove_suptitle_v1():\n    fig, ax = plt.subplots()\n    sup = fig.suptitle('My Suptitle')\n    sup.remove()\n    plt.show()\ndef remove_suptitle_v2():\n    fig = plt.figure(constrained_layout=True)\n    ax = fig.add_subplot()\n    sup = fig.suptitle('My Suptitle')\n    sup.remove()\n    plt.show()\nremove_suptitle_v1() # this works\nremove_suptitle_v2() # this crashes\n```\n\n### Actual outcome\n\n\n```python\n---------------------------------------------------------------------------\nAttributeError                            Traceback (most recent call last)\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/pyplot.py:278, in _draw_all_if_interactive()\n    276 def _draw_all_if_interactive() -\u003e None:\n    277     if matplotlib.is_interactive():\n--\u003e [278](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/pyplot.py:278)         draw_all()\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/_pylab_helpers.py:131, in Gcf.draw_all(cls, force)\n    129 for manager in cls.get_all_fig_managers():\n    130     if force or manager.canvas.figure.stale:\n--\u003e [131](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/_pylab_helpers.py:131)         manager.canvas.draw_idle()\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/backend_bases.py:1893, in FigureCanvasBase.draw_idle(self, *args, **kwargs)\n   1891 if not self._is_idle_drawing:\n   1892     with self._idle_draw_cntx():\n-\u003e [1893](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/backend_bases.py:1893)         self.draw(*args, **kwargs)\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/backends/backend_agg.py:382, in FigureCanvasAgg.draw(self)\n    379 # Acquire a lock on the shared font cache.\n    380 with (self.toolbar._wait_cursor_for_draw_cm() if self.toolbar\n    381       else nullcontext()):\n--\u003e [382](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/backends/backend_agg.py:382)     self.figure.draw(self.renderer)\n    383     # A GUI class may be need to update a window using this draw, so\n    384     # don't forget to call the superclass.\n    385     super().draw()\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/artist.py:94, in _finalize_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer, *args, **kwargs)\n     92 @wraps(draw)\n     93 def draw_wrapper(artist, renderer, *args, **kwargs):\n---\u003e [94](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/artist.py:94)     result = draw(artist, renderer, *args, **kwargs)\n     95     if renderer._rasterizing:\n     96         renderer.stop_rasterizing()\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/artist.py:71, in allow_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer)\n     68     if artist.get_agg_filter() is not None:\n     69         renderer.start_filter()\n---\u003e [71](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/artist.py:71)     return draw(artist, renderer)\n     72 finally:\n     73     if artist.get_agg_filter() is not None:\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/figure.py:3251, in Figure.draw(self, renderer)\n   3249 if self.axes and self.get_layout_engine() is not None:\n   3250     try:\n-\u003e [3251](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/figure.py:3251)         self.get_layout_engine().execute(self)\n   3252     except ValueError:\n   3253         pass\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/layout_engine.py:278, in ConstrainedLayoutEngine.execute(self, fig)\n    275 w_pad = self._params['w_pad'] / width\n    276 h_pad = self._params['h_pad'] / height\n--\u003e [278](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/layout_engine.py:278) return do_constrained_layout(fig, w_pad=w_pad, h_pad=h_pad,\n    279                              wspace=self._params['wspace'],\n    280                              hspace=self._params['hspace'],\n    281                              rect=self._params['rect'],\n    282                              compress=self._compress)\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/_constrained_layout.py:118, in do_constrained_layout(fig, h_pad, w_pad, hspace, wspace, rect, compress)\n    108 for _ in range(2):\n    109     # do the algorithm twice.  This has to be done because decorations\n    110     # change size after the first re-position (i.e. x/yticklabels get\n   (...)\n    114     # make margins for all the Axes and subfigures in the\n    115     # figure.  Add margins for colorbars...\n    116     make_layout_margins(layoutgrids, fig, renderer, h_pad=h_pad,\n    117                         w_pad=w_pad, hspace=hspace, wspace=wspace)\n--\u003e [118](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/_constrained_layout.py:118)     make_margin_suptitles(layoutgrids, fig, renderer, h_pad=h_pad,\n    119                           w_pad=w_pad)\n    121     # if a layout is such that a columns (or rows) margin has no\n    122     # constraints, we need to make all such instances in the grid\n    123     # match in margin size.\n    124     match_submerged_margins(layoutgrids, fig)\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/_constrained_layout.py:480, in make_margin_suptitles(layoutgrids, fig, renderer, w_pad, h_pad)\n    478     if getattr(fig._suptitle, '_autopos', False):\n    479         fig._suptitle.set_position((p[0], 1 - h_pad_local))\n--\u003e [480](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/_constrained_layout.py:480)         bbox = inv_trans_fig(fig._suptitle.get_tightbbox(renderer))\n    481         layoutgrids[fig].edit_margin_min('top', bbox.height + 2 * h_pad)\n    483 if fig._supxlabel is not None and fig._supxlabel.get_in_layout():\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/artist.py:364, in Artist.get_tightbbox(self, renderer)\n    348 def get_tightbbox(self, renderer=None):\n    349     \"\"\"\n    350     Like `.Artist.get_window_extent`, but includes any clipping.\n    351 \n   (...)\n    362         Returns None if clipping results in no intersection.\n    363     \"\"\"\n--\u003e [364](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/artist.py:364)     bbox = self.get_window_extent(renderer)\n    365     if self.get_clip_on():\n    366         clip_box = self.get_clip_box()\n\nFile ~/anaconda3/lib/python3.12/site-packages/matplotlib/text.py:953, in Text.get_window_extent(self, renderer, dpi)\n    951 fig = self.get_figure(root=True)\n    952 if dpi is None:\n--\u003e [953](https://vscode-remote+ssh-002dremote-002bsccpu5-002ecse-002eust-002ehk.vscode-resource.vscode-cdn.net/data/wluak/dataviz-render-update-testing/~/anaconda3/lib/python3.12/site-packages/matplotlib/text.py:953)     dpi = fig.dpi\n    954 if self.get_text() == '':\n    955     with cbook._setattr_cm(fig, dpi=dpi):\n\nAttributeError: 'NoneType' object has no attribute 'dpi'\n```\n\n\n### Expected outcome\n\n\u003cimg width=\"558\" height=\"418\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/03832974-293e-45c0-a413-f7a42b255921\" /\u003e\n\n### Additional information\n\n_No response_\n\n### Operating system\n\n_No response_\n\n### Matplotlib Version\n\n3.10.8\n\n### Matplotlib Backend\n\n_No response_\n\n### Python version\n\n_No response_\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\nNone","author":{"url":"https://github.com/williamlus","@type":"Person","name":"williamlus"},"datePublished":"2026-02-04T07:30:14.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/31073/matplotlib/issues/31073"}