René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Irregular pixel widths in rasterized pcolor","articleBody":"### Bug summary\n\nPixel widths appear irregularly in `pcolor(x, y, z, rasterized=True)`, while `x` and `y` are regular. Using `rasterized=False` provides correct (equal size) pixels, but saving the figure to `.png` (instead of `.pdf`) will show the same irregular pixel width bug.\r\n\r\nIt looks like a resampling bug, which messes up precise data visualization completely.\n\n### Code for reproduction\n\n```python\nimport numpy as np\r\nimport matplotlib.pyplot as plt\r\nx, y = np.meshgrid(range(500), range(2))\r\nz = [np.tile([0,1],250), np.tile([0,1],250)]\r\nfig, ax = plt.subplots(1,1, figsize=(10,2))\r\nim = ax.pcolor(x, y, z, rasterized=True)\r\nax.set_xticks(np.arange(0,40))\r\nfig.savefig('test.pdf')\r\nplt.show()\n```\n\n\n### Actual outcome\n\nIn the resulting plot, some pixels are thinner, and some are thicker, than they should be. \r\n`rasterize=True` (zoom-in to the lower left corner)\r\n![grafik](https://user-images.githubusercontent.com/7942719/177547093-64eb91af-1345-4be1-a04c-e99bd7ccfd49.png)\r\n\n\n### Expected outcome\n\n`rasterize=False` (zoom-in to the lower left corner)\r\n![grafik](https://user-images.githubusercontent.com/7942719/177547007-82796b90-1863-4370-8718-0a1c744b3119.png)\r\n\n\n### Additional information\n\n- This behaviour depends on the number of pixels plotted, for me it becomes visible above `len(x)\u003e100`.\r\n- The spread between thicker and thinner lines increases with increasing size of the input array.\r\n- If the view is reduced to a lower number of pixels (e.g., `ax.set_xlim(0,10)`), the effect is no longer visible.\n\n### Operating system\n\nWindows\n\n### Matplotlib Version\n\n3.5.1\n\n### Matplotlib Backend\n\ninline\n\n### Python version\n\n3.9.6\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\npip","author":{"url":"https://github.com/mschroen","@type":"Person","name":"mschroen"},"datePublished":"2022-07-06T12:22:00.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/23391/matplotlib/issues/23391"}