René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Specifying a Marker as a Tuple seems broken in 3.2","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\nIn matplotlib 3.2 setting a line `marker=(3, 2, 0.0)` (which should be an asterisk style marker with 3 sides and 0 degrees of rotation) causes an error.\r\n\r\n```\r\nAttributeError: 'IdentityTransform' object has no attribute 'scale'\r\n```\r\n\r\nIn version 3.1.2, this error does not occur. It looks like \r\n\r\n\u003c!--A short 1-2 sentences that succinctly describes the bug--\u003e\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\ndef main():\r\n    import matplotlib.pyplot as plt\r\n    fig = plt.figure()\r\n    fig.add_axes()\r\n    ax = fig.gca()\r\n    ax.plot([0, 1, 2], [0, 1, 2], marker=(3, 2, 0.0))\r\n    fig.savefig('foo.png')\r\n\r\n\r\nif __name__ == '__main__':\r\n    main()\r\n```\r\n\r\nThis results in the error: \r\n\r\n```\r\nTraceback (most recent call last):\r\n  File \"/home/joncrall/code/kwplot/dev/mwe_markerstye.py\", line 15, in \u003cmodule\u003e\r\n    main()\r\n  File \"/home/joncrall/code/kwplot/dev/mwe_markerstye.py\", line 7, in main\r\n    fig.savefig('foo.png')\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/figure.py\", line 2203, in savefig\r\n    self.canvas.print_figure(fname, **kwargs)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/backends/backend_qt5agg.py\", line 94, in print_figure\r\n    super().print_figure(*args, **kwargs)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/backend_bases.py\", line 2086, in print_figure\r\n    result = print_method(\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/backends/backend_agg.py\", line 514, in print_png\r\n    FigureCanvasAgg.draw(self)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/backends/backend_agg.py\", line 393, in draw\r\n    self.figure.draw(self.renderer)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/figure.py\", line 1735, in draw\r\n    mimage._draw_list_compositing_images(\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/image.py\", line 137, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/axes/_base.py\", line 2630, in draw\r\n    mimage._draw_list_compositing_images(renderer, self, artists)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/image.py\", line 137, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"/home/joncrall/.local/conda/envs/py38/lib/python3.8/site-packages/matplotlib/lines.py\", line 866, in draw\r\n    marker_trans = marker_trans.scale(w)\r\nAttributeError: 'IdentityTransform' object has no attribute 'scale'\r\n```\r\n\r\nWhile the 3.1.2 version results in a nice plot: \r\n\r\n![image](https://user-images.githubusercontent.com/3186211/76908448-158e3d00-687f-11ea-803e-c329b028fad2.png)\r\n\r\n\r\n**Matplotlib version**\r\n  * Operating system: Linux\r\n  * Matplotlib version: 3.2 (via pip)\r\n  * Matplotlib backend: tried agg and pyqt5\r\n  * Python version: 3.7 and 3.8\r\n\r\nI've identified a possible solution. The main difference seems to be in the `_set_tuple_marker` function. In 3.1.2 it was:\r\n\r\n```python\r\n    def _set_tuple_marker(self):\r\n        marker = self._marker\r\n        if isinstance(marker[0], Number):\r\n            if len(marker) == 2:\r\n                numsides, rotation = marker[0], 0.0\r\n            elif len(marker) == 3:\r\n                numsides, rotation = marker[0], marker[2]\r\n            symstyle = marker[1]\r\n            if symstyle == 0:\r\n                self._path = Path.unit_regular_polygon(numsides)\r\n                self._joinstyle = 'miter'\r\n            elif symstyle == 1:\r\n                self._path = Path.unit_regular_star(numsides)\r\n                self._joinstyle = 'bevel'\r\n            elif symstyle == 2:\r\n                self._path = Path.unit_regular_asterisk(numsides)\r\n                self._filled = False\r\n                self._joinstyle = 'bevel'\r\n            elif symstyle == 3:\r\n                cbook.warn_deprecated(\r\n                    \"3.0\", message=\"Setting a circle marker using `(..., 3)` \"\r\n                    \"is deprecated since Matplotlib 3.0, and support for it \"\r\n                    \"will be removed in 3.2.  Directly pass 'o' instead.\")\r\n                self._path = Path.unit_circle()\r\n            self._transform = Affine2D().scale(0.5).rotate_deg(rotation)\r\n        else:\r\n            cbook.warn_deprecated(\r\n                \"3.0\", message=\"Passing vertices as `(verts, 0)` is \"\r\n                \"deprecated since Matplotlib 3.0, and support for it will be \"\r\n                \"removed in 3.2.  Directly pass `verts` instead.\")\r\n            verts = np.asarray(marker[0])\r\n            path = Path(verts)\r\n            self._set_custom_marker(path)\r\n```\r\n\r\nand in 3.2 it was cleaned up to: \r\n\r\n\r\n```python\r\n    def _set_tuple_marker(self):\r\n        marker = self._marker\r\n        print('marker = {!r}'.format(marker))\r\n        if len(marker) == 2:\r\n            numsides, rotation = marker[0], 0.0\r\n        elif len(marker) == 3:\r\n            numsides, rotation = marker[0], marker[2]\r\n        symstyle = marker[1]\r\n        if symstyle == 0:\r\n            self._path = Path.unit_regular_polygon(numsides)\r\n            self._joinstyle = 'miter'\r\n        elif symstyle == 1:\r\n            self._path = Path.unit_regular_star(numsides)\r\n            self._joinstyle = 'bevel'\r\n        elif symstyle == 2:\r\n            self._path = Path.unit_regular_asterisk(numsides)\r\n            self._filled = False\r\n            self._joinstyle = 'bevel'\r\n        else:\r\n            raise ValueError(f\"Unexpected tuple marker: {marker}\")\r\n```\r\n\r\nHowever, notice that in the second version `self._transform` is never set. Also note that in the 3.2 version the rotation param is never used. I expect that the `self._transform = Affine2D().scale(0.5).rotate_deg(rotation)` line was supposed to be ported, but  never was. Adding it back in seems to fix the issue. \r\n\r\nI noticed it when looking in the lines.py draw method. I saw most markers had an AffineTransform, but the ones I made using the tuple method of initialization has IdentityTransforms. \r\n\r\n","author":{"url":"https://github.com/Erotemic","@type":"Person","name":"Erotemic"},"datePublished":"2020-03-17T22:47:21.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/16811/matplotlib/issues/16811"}