René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: ax.bar raises for all-nan data on matplotlib 3.6.1 ","articleBody":"### Bug summary\n\n`ax.bar` raises an exception in 3.6.1 when passed only nan data. This irrevocably breaks seaborn's histogram function (which draws and then removes a \"phantom\" bar to trip the color cycle).\n\n### Code for reproduction\n\n```python\nimport numpy as np\r\nimport matplotlib.pyplot as plt\r\nf, ax = plt.subplots()\r\nax.bar([np.nan], [np.nan])\n```\n\n\n### Actual outcome\n\n```python-traceback\r\n---------------------------------------------------------------------------\r\nStopIteration                             Traceback (most recent call last)\r\nCell In [1], line 4\r\n      2 import matplotlib.pyplot as plt\r\n      3 f, ax = plt.subplots()\r\n----\u003e 4 ax.bar([np.nan], [np.nan])[0].get_x()\r\n\r\nFile ~/miniconda/envs/py310/lib/python3.10/site-packages/matplotlib/__init__.py:1423, in _preprocess_data.\u003clocals\u003e.inner(ax, data, *args, **kwargs)\r\n   1420 @functools.wraps(func)\r\n   1421 def inner(ax, *args, data=None, **kwargs):\r\n   1422     if data is None:\r\n-\u003e 1423         return func(ax, *map(sanitize_sequence, args), **kwargs)\r\n   1425     bound = new_sig.bind(ax, *args, **kwargs)\r\n   1426     auto_label = (bound.arguments.get(label_namer)\r\n   1427                   or bound.kwargs.get(label_namer))\r\n\r\nFile ~/miniconda/envs/py310/lib/python3.10/site-packages/matplotlib/axes/_axes.py:2373, in Axes.bar(self, x, height, width, bottom, align, **kwargs)\r\n   2371 x0 = x\r\n   2372 x = np.asarray(self.convert_xunits(x))\r\n-\u003e 2373 width = self._convert_dx(width, x0, x, self.convert_xunits)\r\n   2374 if xerr is not None:\r\n   2375     xerr = self._convert_dx(xerr, x0, x, self.convert_xunits)\r\n\r\nFile ~/miniconda/envs/py310/lib/python3.10/site-packages/matplotlib/axes/_axes.py:2182, in Axes._convert_dx(dx, x0, xconv, convert)\r\n   2170 try:\r\n   2171     # attempt to add the width to x0; this works for\r\n   2172     # datetime+timedelta, for instance\r\n   (...)\r\n   2179     # removes the units from unit packages like `pint` that\r\n   2180     # wrap numpy arrays.\r\n   2181     try:\r\n-\u003e 2182         x0 = cbook._safe_first_finite(x0)\r\n   2183     except (TypeError, IndexError, KeyError):\r\n   2184         pass\r\n\r\nFile ~/miniconda/envs/py310/lib/python3.10/site-packages/matplotlib/cbook/__init__.py:1749, in _safe_first_finite(obj, skip_nonfinite)\r\n   1746     raise RuntimeError(\"matplotlib does not \"\r\n   1747                        \"support generators as input\")\r\n   1748 else:\r\n-\u003e 1749     return next(val for val in obj if safe_isfinite(val))\r\n\r\nStopIteration: \r\n```\n\n### Expected outcome\n\nOn 3.6.0 this returns a `BarCollection` with one Rectangle, having `nan` for `x` and `height`.\n\n### Additional information\n\nI assume it's related to this bullet in the release notes:\r\n\r\n- Fix barplot being empty when first element is NaN\r\n\r\nBut I don't know the context for it to investigate further (could these link to PRs?)\r\n\r\nFurther debugging:\r\n\r\n```python\r\nax.bar([np.nan], [0])  # Raises\r\nax.bar([0], [np.nan])  # Works\r\n```\r\n\r\nSo it's about the x position specifically.\n\n### Operating system\n\nMacos\n\n### Matplotlib Version\n\n3.6.1\n\n### Matplotlib Backend\n\n_No response_\n\n### Python version\n\n_No response_\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\npip","author":{"url":"https://github.com/mwaskom","@type":"Person","name":"mwaskom"},"datePublished":"2022-10-08T12:04:30.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/24127/matplotlib/issues/24127"}