René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Cannot create empty FancyArrow (expired numpy deprecation)","articleBody":"### Bug summary\n\nCreating an empty FancyArrow throws an exception:\n```\n\u003e\u003e\u003e import matplotlib.pyplot as plt\n\n\u003e\u003e\u003e plt.arrow([], [], [], [])\n\nmatplotlib/axes/_axes.py\", line 5509, in arrow\n    a = mpatches.FancyArrow(x, y, dx, dy, **kwargs)\nmatplotlib/patches.py\", line 1459, in __init__\n    self._make_verts()\nmatplotlib/patches.py\", line 1518, in _make_verts\n    if not length:\n           ^^^^^^\nValueError: The truth value of an empty array is ambiguous. Use `array.size \u003e 0` to check that an array is not empty.\n```\nThat exception used to throw a numpy deprecation warning, but that deprecation [has recently expired](https://numpy.org/doc/stable/release/2.2.0-notes.html#expired-deprecations) and now throws an exception.\n\nThat section appears to intend to properly handle zero-length input (matplotlib/patches.py\", line 1518),\n```python\n    if not length:\n            self.verts = np.empty([0, 2])  # display nothing if empty\n```\n\nThe fix appears to be to change the `if not length` to `if length.size == 0`.\n\n### Code for reproduction\n\n```Python\nimport matplotlib.pyplot as plt\n\nplt.arrow([], [], [], [])\n```\n\n### Actual outcome\n\n```\nmatplotlib/axes/_axes.py\", line 5509, in arrow\n    a = mpatches.FancyArrow(x, y, dx, dy, **kwargs)\nmatplotlib/patches.py\", line 1459, in __init__\n    self._make_verts()\nmatplotlib/patches.py\", line 1518, in _make_verts\n    if not length:\n           ^^^^^^\nValueError: The truth value of an empty array is ambiguous. Use `array.size \u003e 0` to check that an array is not empty.\n```\n\n### Expected outcome\n\nReturn a valid `FancyArrow`\n\n### Additional information\n\npython version 3.12\nmatplotlib version: 3.10.3 (latest release)\nnumpy version: 2.2.6 (deprecation above expired in 2.2.0, released Dec 2024)\n\n### Operating system\n\n_No response_\n\n### Matplotlib Version\n\n3.10.3\n\n### Matplotlib Backend\n\n_No response_\n\n### Python version\n\n3.12.8\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\npip","author":{"url":"https://github.com/ap2468","@type":"Person","name":"ap2468"},"datePublished":"2025-07-01T23:13:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/30242/matplotlib/issues/30242"}