René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Major speed regression introduced in \"plt.bar\" definition clipping between 3.0.3 and 3.3.0.","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\nAs I updated Matplolib from version 3.0.3 to version 3.3.0 I noticed that [Colour](https://github.com/colour-science/colour/) unit test time skyrocketed: our plotting sub-package test suite went from 120 seconds to around 3000 seconds!\r\n\r\nI quickly noticed that it was related to definitions using the spectrum plot:\r\n\r\n![image](https://user-images.githubusercontent.com/99779/87933498-78b80680-cae1-11ea-8bf5-b09af15cec50.png)\r\n\r\nThis definition is using `plt.bar` and as I suspected that polygon clipping might be the culprit, I ran some tests on one of the offending definitions while keeping and removing the polygon clipping:\r\n\r\n*With Polygon Clipping*\r\n\r\n```python\r\n\u003e\u003e\u003e import timeit\r\n\u003e\u003e\u003e import colour\r\n\u003e\u003e\u003e timeit.timeit(lambda : colour.plotting.plot_single_illuminant_sd(filename='test.png'), number=1)\r\n59.81594165299998\r\n```\r\n\r\n*Without Polygon Clipping*\r\n```python\r\n\u003e\u003e\u003e import timeit\r\n\u003e\u003e\u003e import colour\r\n\u003e\u003e\u003e timeit.timeit(lambda : colour.plotting.plot_single_illuminant_sd(filename='test.png'), number=1)\r\n1.3159556400000056\r\n```\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\nI haven't created a reproducible case but my assumption is that the clipping code is orders of magnitude slower than before, the definition I used is available here: https://github.com/colour-science/colour/blob/d5f68005f62fc86ba59745bd4c8bb8a01bb5dcb4/colour/plotting/colorimetry.py#L183 and the meat is roughly as follows:\r\n\r\n```python\r\n    polygon = Polygon(\r\n        np.vstack([\r\n            (x_min, 0),\r\n            tstack([wavelengths, values]),\r\n            (x_max, 0),\r\n        ]),\r\n        facecolor='none',\r\n        edgecolor='none')\r\n    axes.add_patch(polygon)\r\n\r\n    padding = 0.1\r\n    axes.bar(\r\n        x=wavelengths - padding,\r\n        height=max(values),\r\n        width=1 + padding,\r\n        color=colours,\r\n        align='edge',\r\n        clip_path=polygon)\r\n```\r\n\r\nThere are roughly 450 wavelengths and each one of them generates a coloured bar.\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: macOS 10.15.5\r\n  * Matplotlib version: 3.3.0\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): MacOSX\r\n  * Python version: 3.8\r\n  * Jupyter version (if applicable):\r\n  * Other libraries: \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\nMatplotlib was installed with Pip.\r\n\r\n","author":{"url":"https://github.com/thomasmansencal","@type":"Person","name":"thomasmansencal"},"datePublished":"2020-07-20T11:45:02.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/17974/matplotlib/issues/17974"}