René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Axes.imshow draws invalid color at value is 0 when max of 'X' not equal to vmax","articleBody":"\u003c!--To help us understand and resolve your issue, please fill out the form to the best of your ability.--\u003e\r\n\u003c!--You can feel free to delete the sections that do not apply.--\u003e\r\n\r\n### Bug report\r\n\r\n**Bug summary**\r\n\r\nAxes.imshow draws invalid color at cells which value is 0 when max value of parameter 'X' is not equal to parameter 'vmax'\r\n\r\n**Code for reproduction**\r\n\r\n\u003c!--A minimum code snippet required to reproduce the bug.\r\nPlease make sure to minimize the number of dependencies required, and provide\r\nany necessary plotted data.\r\nAvoid using threads, as Matplotlib is (explicitly) not thread-safe.--\u003e\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\nimport matplotlib.ticker as ticker\r\nimport numpy as np\r\n\r\ncmap = plt.cm.get_cmap('autumn_r')\r\ncmap.set_under(color='lightgrey')\r\n\r\nfig = plt.figure()\r\nax = fig.add_subplot()\r\nax.grid(which='major', color='white', linestyle='dotted', alpha=0.7)\r\nax.grid(which='minor', color='white', linestyle='dotted', alpha=0.5)\r\n\r\ndata = np.array([[-1, -1, -1, 0, 0, 0, 0, 43, 79, 95, 66, 1, -1, -1, -1, 0, 0, 0, 34]])\r\n# data = np.array([[-1, -1, -1, 0, 0, 0, 0, 43, 79, 100, 66, 1, -1, -1, -1, 0, 0, 0, 34]])\r\nim = ax.imshow(data, aspect='auto', cmap=cmap, vmin=0, vmax=100)\r\nax.xaxis.set_major_locator(ticker.MultipleLocator())\r\nax.set_yticks([0])\r\nfig.colorbar(im)\r\n\r\nplt.show()\r\n```\r\n\r\n**Actual outcome**\r\n\r\nI expect yellow at cells 3, 4, 5, 6, 15, 16, 17. but they are grey.\r\n\r\n![Figure_max95](https://user-images.githubusercontent.com/25410805/77616306-a8f8f980-6f74-11ea-935b-25c2f568ac24.png)\r\n\r\n**Expected outcome**\r\n\r\nif using commented data(max(data) == vmax), got output below. that is valid.\r\n![Figure_max100](https://user-images.githubusercontent.com/25410805/77616420-efe6ef00-6f74-11ea-91c6-67b6a183db13.png)\r\n\r\n\r\n\u003c!--A description of the expected outcome from the code snippet--\u003e\r\n\u003c!--If this used to work in an earlier version of Matplotlib, please note the version it used to work on--\u003e\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: Windows10\r\n  * Matplotlib version: 3.1.3\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): TkAgg\r\n  * Python version: 3.7.4\r\n\r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\n","author":{"url":"https://github.com/fifzteen","@type":"Person","name":"fifzteen"},"datePublished":"2020-03-26T06:27:36.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":30},"url":"https://github.com/16910/matplotlib/issues/16910"}