René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Scatterplot: should vmin/vmax be ignored when a norm is specified?","articleBody":"### Bug report\r\n\r\n**Bug summary**\r\n\r\nThe `scatter` documentation says:\r\n\r\n\u003e *vmin* and *vmax* are ignored if you pass a *norm* instance.\r\n\r\nHowever, it seems that this is not the case. Is the documentation correct of the behaviour?\r\n\r\n**Code for reproduction**\r\n\r\n```python\r\nimport numpy as np\r\nimport matplotlib.pyplot as plt\r\nimport matplotlib\r\n\r\ncmap = matplotlib.cm.viridis_r\r\nnorm = matplotlib.colors.BoundaryNorm([1,3,6,8], cmap.N, clip=True)\r\n\r\nvalues = np.arange(10)\r\n\r\n# only specifying a norm\r\nplt.scatter(values, values, c=values, norm=norm)\r\n\r\n# also specifying vmin/vmax. Should those be ignored?\r\nplt.scatter(values, values, c=values, norm=norm, vmin=6, vmax=10)\r\n```\r\n\r\n**Actual outcome**\r\n\r\n```\r\n# only specifying a norm\r\nplt.scatter(values, values, c=values, norm=norm)\r\n```\r\n\r\n![index](https://user-images.githubusercontent.com/1020496/59982970-2d9b9d80-961a-11e9-9303-4d6ccf29ec4b.png)\r\n\r\n```\r\n# also specifying vmin/vmax. Should those be ignored?\r\nplt.scatter(values, values, c=values, norm=norm, vmin=6, vmax=10)\r\n```\r\n\r\n![index2](https://user-images.githubusercontent.com/1020496/59982972-2ffdf780-961a-11e9-9dd4-b0a92b74e0d5.png)\r\n\r\nSo the vmin/vmax have clearly \"altered\" the BoundaryNorm applied on the data.\r\n\r\nAccording to the documentation, this should not happen. \r\nSpecifically for a BoundaryNorm (with specified bounds), it seems strange let the plotting change those bounds.\r\n\r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system: Ubuntu 16.04\r\n  * Matplotlib version: 3.1.0\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): notebook inline backend\r\n  * Python version: 3.7\r\n  * Installed from conda-forge\r\n","author":{"url":"https://github.com/jorisvandenbossche","@type":"Person","name":"jorisvandenbossche"},"datePublished":"2019-06-23T22:54:25.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/14603/matplotlib/issues/14603"}