René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[ENH]: Improve plt.arrow default head shape","articleBody":"### Problem\r\n\r\nThe default for the head width/length of the fancy arrow patch are not very good. See for example: https://philbull.wordpress.com/2012/04/05/drawing-arrows-in-matplotlib/\r\n\r\nThis means that in order to get a usable arrow you need to mess around with options such as `head_length` which can be tricky to learn about. \r\n\r\n### Proposed solution\r\n\r\nUse a new heuristic for head sizing as a default behavior. \r\n\r\n@kmdalton suggested the below function `norm_arrow` which you can see gives better defaults in two basic test cases.\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\nfig, axes = plt.subplots(2,2)\r\n\r\nlims = (\r\n    [-1, 1],\r\n    [-10,10],\r\n)\r\n\r\ndef norm_arrow(ax, x1, y1, x2, y2, head_scale=0.1, head_width=None, **kwargs):\r\n    norm = np.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1))\r\n    l = head_scale*norm\r\n    w = head_width if head_width is not None else 0.5*l\r\n    ax.arrow(x1, y1, x2, y2, head_width=w, head_length=l, length_includes_head=True, **kwargs)\r\n\r\naxes[0][1].set_title(\"Norm based default\")\r\naxes[0][0].set_title(\"Current Default\")\r\n\r\nfor axs, lim in zip(axes, lims):\r\n    axs[0].set_ylim(lim)\r\n    axs[0].set_xlim(lim)\r\n    axs[1].set_ylim(lim)\r\n    axs[1].set_xlim(lim)\r\n\r\n    axs[0].arrow( 0, 0, lim[1]/2, lim[1]/2, fc=\"k\", ec=\"k\" )\r\n    norm_arrow(axs[1], 0, 0, lim[1]/2, lim[1]/2, fc=\"k\", ec=\"k\" )\r\n\r\nplt.show()\r\n```\r\n\r\n![image](https://user-images.githubusercontent.com/10111092/152208475-47fb6e1d-dfa3-4223-bc19-5089f2b24a92.png)\r\n","author":{"url":"https://github.com/ianhi","@type":"Person","name":"ianhi"},"datePublished":"2022-02-02T17:45:08.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/22379/matplotlib/issues/22379"}