René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Cannot draw arrow from polar plot origin after setting rticks","articleBody":"### Bug summary\n\nI am trying to create a polar plot of some data, with an annotation arrow pointing towards some other point in the plot. However, I get a StopIteration, presumably because of setting the rticks, which unexpectedly excludes the origin from the radius limits.\n\n### Code for reproduction\n\n```Python\nimport numpy as np\nimport matplotlib.pyplot as plt\n\n# Radius, random numbers in [0, 1)\nrng = np.random.default_rng(seed=42)\nr = rng.random((24,))\n\n# 0 to 2pi\ntheta = np.linspace(0, 2, 24, endpoint=False) * np.pi\n\nfig, ax = plt.subplots(subplot_kw={'projection': 'polar'})\n\n# Data to plot\nax.plot(theta, r)\nax.scatter(theta, r, c=r, cmap='viridis')\nax.set_rticks([1, 2, 3])  # Less radial ticks\nax.grid(True)\n\n# Where the annotation arrow should point\nan_r = 0.670\nan_theta = 0.820\n\n# Visualise arrow end-point\nax.scatter(an_theta, an_r)\n\n# Create arrow\nax.annotate('',\n            xy=(an_theta, an_r),  # theta, radius\n            xytext=(0, 0), \n            arrowprops=dict(facecolor='black', shrink=0),\n            horizontalalignment='right'\n            )\n\nplt.show()\n```\n\n### Actual outcome\n\n---------------------------------------------------------------------------\nStopIteration                             Traceback (most recent call last)\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/IPython/core/formatters.py:340](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/IPython/core/formatters.py#line=339), in BaseFormatter.__call__(self, obj)\n    338     pass\n    339 else:\n--\u003e 340     return printer(obj)\n    341 # Finally look for special method names\n    342 method = get_real_method(obj, self.print_method)\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/IPython/core/pylabtools.py:152](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/IPython/core/pylabtools.py#line=151), in print_figure(fig, fmt, bbox_inches, base64, **kwargs)\n    149     from matplotlib.backend_bases import FigureCanvasBase\n    150     FigureCanvasBase(fig)\n--\u003e 152 fig.canvas.print_figure(bytes_io, **kw)\n    153 data = bytes_io.getvalue()\n    154 if fmt == 'svg':\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/backend_bases.py:2342](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/backend_bases.py#line=2341), in FigureCanvasBase.print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, bbox_inches, pad_inches, bbox_extra_artists, backend, **kwargs)\n   2336     renderer = _get_renderer(\n   2337         self.figure,\n   2338         functools.partial(\n   2339             print_method, orientation=orientation)\n   2340     )\n   2341     with getattr(renderer, \"_draw_disabled\", nullcontext)():\n-\u003e 2342         self.figure.draw(renderer)\n   2344 if bbox_inches:\n   2345     if bbox_inches == \"tight\":\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py:95](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py#line=94), in _finalize_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer, *args, **kwargs)\n     93 @wraps(draw)\n     94 def draw_wrapper(artist, renderer, *args, **kwargs):\n---\u003e 95     result = draw(artist, renderer, *args, **kwargs)\n     96     if renderer._rasterizing:\n     97         renderer.stop_rasterizing()\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py:72](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py#line=71), in allow_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer)\n     69     if artist.get_agg_filter() is not None:\n     70         renderer.start_filter()\n---\u003e 72     return draw(artist, renderer)\n     73 finally:\n     74     if artist.get_agg_filter() is not None:\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/figure.py:3140](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/figure.py#line=3139), in Figure.draw(self, renderer)\n   3137         # ValueError can occur when resizing a window.\n   3139 self.patch.draw(renderer)\n-\u003e 3140 mimage._draw_list_compositing_images(\n   3141     renderer, self, artists, self.suppressComposite)\n   3143 for sfig in self.subfigs:\n   3144     sfig.draw(renderer)\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/image.py:131](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/image.py#line=130), in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)\n    129 if not_composite or not has_images:\n    130     for a in artists:\n--\u003e 131         a.draw(renderer)\n    132 else:\n    133     # Composite any adjacent images together\n    134     image_group = []\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py:39](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py#line=38), in _prevent_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer, *args, **kwargs)\n     36     renderer.stop_rasterizing()\n     37     renderer._rasterizing = False\n---\u003e 39 return draw(artist, renderer, *args, **kwargs)\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/projections/polar.py:1037](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/projections/polar.py#line=1036), in PolarAxes.draw(self, renderer)\n   1034     self.yaxis.reset_ticks()\n   1035     self.yaxis.set_clip_path(self.patch)\n-\u003e 1037 super().draw(renderer)\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py:72](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py#line=71), in allow_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer)\n     69     if artist.get_agg_filter() is not None:\n     70         renderer.start_filter()\n---\u003e 72     return draw(artist, renderer)\n     73 finally:\n     74     if artist.get_agg_filter() is not None:\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/axes/_base.py:3064](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/axes/_base.py#line=3063), in _AxesBase.draw(self, renderer)\n   3061 if artists_rasterized:\n   3062     _draw_rasterized(self.figure, artists_rasterized, renderer)\n-\u003e 3064 mimage._draw_list_compositing_images(\n   3065     renderer, self, artists, self.figure.suppressComposite)\n   3067 renderer.close_group('axes')\n   3068 self.stale = False\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/image.py:131](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/image.py#line=130), in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)\n    129 if not_composite or not has_images:\n    130     for a in artists:\n--\u003e 131         a.draw(renderer)\n    132 else:\n    133     # Composite any adjacent images together\n    134     image_group = []\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py:72](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py#line=71), in allow_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer)\n     69     if artist.get_agg_filter() is not None:\n     70         renderer.start_filter()\n---\u003e 72     return draw(artist, renderer)\n     73 finally:\n     74     if artist.get_agg_filter() is not None:\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/text.py:2032](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/text.py#line=2031), in Annotation.draw(self, renderer)\n   2030     if self.arrow_patch.figure is None and self.figure is not None:\n   2031         self.arrow_patch.figure = self.figure\n-\u003e 2032     self.arrow_patch.draw(renderer)\n   2033 # Draw text, including FancyBboxPatch, after FancyArrowPatch.\n   2034 # Otherwise, a wedge arrowstyle can land partly on top of the Bbox.\n   2035 Text.draw(self, renderer)\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py:39](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/artist.py#line=38), in _prevent_rasterization.\u003clocals\u003e.draw_wrapper(artist, renderer, *args, **kwargs)\n     36     renderer.stop_rasterizing()\n     37     renderer._rasterizing = False\n---\u003e 39 return draw(artist, renderer, *args, **kwargs)\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py:4352](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py#line=4351), in FancyArrowPatch.draw(self, renderer)\n   4348 # FIXME: dpi_cor is for the dpi-dependency of the linewidth.  There\n   4349 # could be room for improvement.  Maybe _get_path_in_displaycoord could\n   4350 # take a renderer argument, but get_path should be adapted too.\n   4351 self._dpi_cor = renderer.points_to_pixels(1.)\n-\u003e 4352 path, fillable = self._get_path_in_displaycoord()\n   4354 if not np.iterable(fillable):\n   4355     path = [path]\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py:4327](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py#line=4326), in FancyArrowPatch._get_path_in_displaycoord(self)\n   4325     posB = self._convert_xy_units(self._posA_posB[1])\n   4326     (posA, posB) = self.get_transform().transform((posA, posB))\n-\u003e 4327     _path = self.get_connectionstyle()(posA, posB,\n   4328                                        patchA=self.patchA,\n   4329                                        patchB=self.patchB,\n   4330                                        shrinkA=self.shrinkA * dpi_cor,\n   4331                                        shrinkB=self.shrinkB * dpi_cor\n   4332                                        )\n   4333 else:\n   4334     _path = self.get_transform().transform_path(self._path_original)\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py:2732](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py#line=2731), in ConnectionStyle._Base.__call__(self, posA, posB, shrinkA, shrinkB, patchA, patchB)\n   2726 path = self.connect(posA, posB)\n   2727 path = self._clip(\n   2728     path,\n   2729     self._in_patch(patchA) if patchA else None,\n   2730     self._in_patch(patchB) if patchB else None,\n   2731 )\n-\u003e 2732 path = self._clip(\n   2733     path,\n   2734     inside_circle(*path.vertices[0], shrinkA) if shrinkA else None,\n   2735     inside_circle(*path.vertices[-1], shrinkB) if shrinkB else None\n   2736 )\n   2737 return path\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py:2710](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/patches.py#line=2709), in ConnectionStyle._Base._clip(self, path, in_start, in_stop)\n   2708 if in_start:\n   2709     try:\n-\u003e 2710         _, path = split_path_inout(path, in_start)\n   2711     except ValueError:\n   2712         pass\n\nFile [~/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/bezier.py:351](/home/preclineu/.conda/envs/graph_svd/lib/python3.11/site-packages/matplotlib/bezier.py#line=350), in split_path_inout(path, inside, tolerance, reorder_inout)\n    348 from .path import Path\n    349 path_iter = path.iter_segments()\n--\u003e 351 ctl_points, command = next(path_iter)\n    352 begin_inside = inside(ctl_points[-2:])  # true if begin point is inside\n    354 ctl_points_old = ctl_points\n\nStopIteration:\n\n### Expected outcome\n\nEither a more descriptive error that the annotation arrow falls outside the axes limits or the image:\n![Image](https://github.com/user-attachments/assets/e4fbd5d9-8e85-4f9e-899e-bd15c8065192)\n\n### Additional information\n\nThis behaviour is quite erratic because the plot works fine if I 1) use different values for r, 2) comment the ax.set_rticks(...) line, 3) comment ax.annotate(...), 4) comment ax.scatter(an_theta, an_r), etc. The stacktrace seems to imply that the error occurs when the annotation arrow is being drawn.\n\n[Someone on SO](https://stackoverflow.com/questions/79382801/why-is-there-a-stopiteration-error-for-too-many-items-in-matplotlib-polar-plot?noredirect=1#comment139994674_79382801) suggested that the problem might be due to the Axes limits being set when setting the rticks. Indeed, `ax.set_rlim(0, 1)` produces the expected plot. However, I'd then expect `ax.set_rticks([0, 1, 2, 3])` to also make it work, but that does not seem to be the case.\n\n### Operating system\n\nAlmalinux 8.6\n\n### Matplotlib Version\n\n3.7.1\n\n### Matplotlib Backend\n\nmodule://matplotlib_inline.backend_inline\n\n### Python version\n\n3.11.4\n\n### Jupyter version\n\n4.2.5\n\n### Installation\n\nconda","author":{"url":"https://github.com/Valkje","@type":"Person","name":"Valkje"},"datePublished":"2025-01-24T17:28:49.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/29516/matplotlib/issues/29516"}