René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"calling annotate with nan values for the position still gives error after 3.0.2","articleBody":"### Bug report\r\n\r\n**Bug summary**\r\n\r\nThere was a previous issue #12648 which noted a regression in Matplotlib which meant calling annotate with a nan position caused an error when using the command `plt.tight_layout()`. This issue was then closed by #12651, however with Matplotlib 3.0.2 I still am recieving an error with the following code, which I think should be functionally the same:\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\n\r\nfig, ax = plt.subplots()\r\n\r\nax.annotate(\"\", xy=(0, float('nan')))\r\n\r\n# If axis is set on then a ValueError is thrown when calculating ticks\r\n# If axis is set off then a RuntimeError: libpng signaled error is thrown\r\nax.set_axis_off()\r\nfig.savefig(\"bar.png\", bbox_inches='tight')\r\n```\r\n\r\n**Actual outcome**\r\n\r\n```\r\nlibpng warning: Image width is zero in IHDR\r\nlibpng warning: Image height is zero in IHDR\r\nlibpng error: Invalid IHDR data\r\nTraceback (most recent call last):\r\n  File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\r\n  File \"/Users/michael/conda/envs/nnpdf/lib/python3.7/site-packages/matplotlib/figure.py\", line 2094, in savefig\r\n    self.canvas.print_figure(fname, **kwargs)\r\n  File \"/Users/michael/conda/envs/nnpdf/lib/python3.7/site-packages/matplotlib/backend_bases.py\", line 2075, in print_figure\r\n    **kwargs)\r\n  File \"/Users/michael/conda/envs/nnpdf/lib/python3.7/site-packages/matplotlib/backends/backend_agg.py\", line 523, in print_png\r\n    self.figure.dpi, metadata=metadata)\r\nRuntimeError: libpng signaled error\r\n```\r\n\r\n**Expected outcome**\r\n\r\nI think this minimal example should just return an empty figure and ignore the annotation with NaN position. Maybe I'm mistaken but I would have thought it should be the same output as\r\n```\r\nplt.tight_layout()\r\nplt.savefig(\"bar.png\")\r\n```\r\nwhich does work as per the #12651\r\n\r\n**Matplotlib version**\r\n  * Operating system: OSX, but also tested on linux\r\n  * Matplotlib version: 3.0.2\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): TkAgg\r\n  * Python version: 3.7.2\r\n\r\n(conda installation)\r\n\r\n\r\n","author":{"url":"https://github.com/wilsonmr","@type":"Person","name":"wilsonmr"},"datePublished":"2019-01-24T12:18:17.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/13276/matplotlib/issues/13276"}