René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: RuntimeError when bar_label of stacked bar chart comes to rest outside of plot's Y limit","articleBody":"### Bug summary\r\n\r\nWhen creating a stacked bar chart and annotating its components by use of the `bar_label` method, a `RuntimeError(\"Unknown return type\")` exception is raised the moment one of the bar labels comes to rest outside the specified Y limits.\r\n\r\n### Code for reproduction\r\n\r\n```python\r\n#!/usr/bin/env python3\r\n\r\nfrom matplotlib import pyplot\r\nimport numpy as np\r\n\r\ndef main():\r\n    categories = [\"Foo\", \"Bar\", \"Baz\", \"Barbaz\"]\r\n    data = {\r\n            \"Apples\": [0, 1, 2, 3],\r\n            \"Oranges\": [2, 5, 27, 1],\r\n            \"Pears\": [17, 22, 15, 10],\r\n    }\r\n\r\n    grid = (1, 1)\r\n    fig = pyplot.figure(figsize=(9, 9), dpi=300, layout=\"constrained\")\r\n    ax = pyplot.subplot2grid(grid, (0, 0), fig=fig)\r\n\r\n    bottom = np.zeros(len(categories))\r\n    width = 0.5\r\n\r\n    for fruit, values in data.items():\r\n        p = ax.bar(\r\n                categories,\r\n                values,\r\n                width,\r\n                label=fruit,\r\n                bottom=bottom,\r\n        )\r\n\r\n        ax.bar_label(p, label_type='center')\r\n\r\n        bottom += values\r\n\r\n\r\n    # The exception happens if the Y-limit of the plot is chosen too low.\r\n\r\n    # This limit is fine, the whole graph fits\r\n    # ax.set(ylim=(0, 50))\r\n\r\n    # This limit is fine as well, even though it cuts off the top of the\r\n    # topmost bar.\r\n    # ax.set(ylim=(0, 35))\r\n\r\n    # This limit is fine still, with the topmost label ('15' of the 'Baz'\r\n    # category) being on the top border of the plot.\r\n    # ax.set(ylim=(0, 29))\r\n\r\n    # This limit produces an exception, likely as the topmost label ('15' of\r\n    # the 'Baz' category) cannot be placed anymore, since its bar's lower\r\n    # end starts at 2+27 = 29.\r\n    ax.set(ylim=(0, 28))\r\n\r\n    fig.savefig(\"/tmp/matplotlib_example.png\", format=\"png\")\r\n\r\nif __name__ == '__main__':\r\n    main()\r\n```\r\n\r\n\r\n### Actual outcome\r\n\r\n```\r\n(matplotlib-bar-label-mre)matplotlib-bar-label-mre › python demo.py \r\nTraceback (most recent call last):\r\n  File \"/home/michael/dev/python/matplotlib-bar-label-mre/demo.py\", line 56, in \u003cmodule\u003e\r\n    main()\r\n  File \"/home/michael/dev/python/matplotlib-bar-label-mre/demo.py\", line 53, in main\r\n    fig.savefig(\"/tmp/matplotlib_example.png\", format=\"png\")\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/figure.py\", line 3343, in savefig\r\n    self.canvas.print_figure(fname, **kwargs)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/backend_bases.py\", line 2342, in print_figure\r\n    self.figure.draw(renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/artist.py\", line 95, in draw_wrapper\r\n    result = draw(artist, renderer, *args, **kwargs)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/artist.py\", line 72, in draw_wrapper\r\n    return draw(artist, renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/figure.py\", line 3134, in draw\r\n    self.get_layout_engine().execute(self)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/layout_engine.py\", line 253, in execute\r\n    return do_constrained_layout(fig, w_pad=w_pad, h_pad=h_pad,\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/_constrained_layout.py\", line 119, in do_constrained_layout\r\n    make_layout_margins(layoutgrids, fig, renderer, h_pad=h_pad,\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/_constrained_layout.py\", line 369, in make_layout_margins\r\n    pos, bbox = get_pos_and_bbox(ax, renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/_constrained_layout.py\", line 617, in get_pos_and_bbox\r\n    tightbbox = martist._get_tightbbox_for_layout_only(ax, renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/artist.py\", line 1415, in _get_tightbbox_for_layout_only\r\n    return obj.get_tightbbox(*args, **{**kwargs, \"for_layout_only\": True})\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/axes/_base.py\", line 4408, in get_tightbbox\r\n    bbox = a.get_tightbbox(renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/text.py\", line 2064, in get_tightbbox\r\n    return super().get_tightbbox(renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/artist.py\", line 367, in get_tightbbox\r\n    bbox = self.get_window_extent(renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/text.py\", line 2050, in get_window_extent\r\n    self.update_positions(self._renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/text.py\", line 1954, in update_positions\r\n    self.set_transform(self._get_xy_transform(renderer, self.anncoords))\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/text.py\", line 1538, in _get_xy_transform\r\n    xy0 = self._get_ref_xy(renderer)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/text.py\", line 1569, in _get_ref_xy\r\n    return self._get_xy(renderer, *self.xy, self.xycoords)\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/text.py\", line 1478, in _get_xy\r\n    return self._get_xy_transform(renderer, s).transform((x, y))\r\n  File \"/home/michael/.local/share/virtualenvs/matplotlib-bar-label-mre/lib/python3.10/site-packages/matplotlib/text.py\", line 1496, in _get_xy_transform\r\n    raise RuntimeError(\"Unknown return type\")\r\nRuntimeError: Unknown return type\r\n```\r\n\r\n### Expected outcome\r\n\r\nI'd expect the corresponding section of the bar, along with its label, to simply be outside the visible plot area. Or at least a more descriptive error message.\r\n\r\n\r\n### Additional information\r\n\r\nThe exception seems to happen the moment one of the bar labels cannot fit in the visible plot area anymore. This can be seen by starting with a large Y limit, and slowly lowering it.\r\n\r\nAs the Y limit approaches the position of the topmost label, it will be shifted down on its own. However the moment the Y limit is set low enough that the topmost bar's component is fully outside the visible area, the exception arises.\r\n\r\nThe (mostly) minimal reproducible example above contains several Y limits to indicate this happening.\r\n\r\n### Operating system\r\n\r\nArch Linux, Linux 6.2.5\r\n\r\n### Matplotlib Version\r\n\r\n3.7.1\r\n\r\n### Matplotlib Backend\r\n\r\nTkAgg\r\n\r\n### Python version\r\n\r\n3.10.9\r\n\r\n### Jupyter version\r\n\r\nNot applicable\r\n\r\n### Installation\r\n\r\npip","author":{"url":"https://github.com/Lavode","@type":"Person","name":"Lavode"},"datePublished":"2023-04-05T14:24:48.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/25625/matplotlib/issues/25625"}