René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Non-sensical negative radial scale minimum autoset in polar plot","articleBody":"When plotting a set of data on a polar plot, the default bottom y_limit might not be zero unexpectedly from the perspective of the user, resulting in confusion about the meaning of the plot, especially for a person (like me) unfamiliar with the concept of a polar plot where r=0 is not at the very center point of the plot.\r\n\r\n**In a Jupyter Notebook**\r\n\r\n```python\r\n%pylab inline\r\nnpoints = 10_000\r\ntheta = 360 * random.random(npoints)\r\nr = random.random(npoints)\r\n\r\nfig, (ax1, ax2) = subplots(1, 2, figsize=(8, 4), dpi=120, facecolor='white', subplot_kw=dict(projection='polar'))\r\nax1.plot(radians(theta), r, 'o', markersize=1)\r\nax1.set_title('expected', pad=12)\r\nax2.plot(radians(theta), r, 'o', markersize=1)\r\nax2.set_title('unexpected', pad=12)\r\nax1.set_ylim(bottom=0)\r\n# ax2.set_ylim(bottom=0)\r\nprint(ax2.get_ylim())\r\n```\r\n    \u003e\u003e\u003e (-0.04989219852580686, 1.0497180912808268)\r\n\r\n![image](https://user-images.githubusercontent.com/9872343/51791999-235f9b00-2171-11e9-9ea4-ac823720260f.png)\r\n\r\n\r\nI ran across this when plotting data and wondering if I had a bug in my analysis somewhere that was giving me a hole around the origin.  It took me some time to figure out that the problem was simply in the axis scaling as I expected the version on the left (which seems sensible to me as the default) and not the version on the right which has a hole in the middle.\r\n\r\n**Matplotlib version**\r\n\r\n  * Operating system: Windows 10, also Ubuntu Linux\r\n  * Matplotlib version: 3.0.2 from pip\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): inline\r\n  * Python version: 3.7, 3.6\r\n  * Jupyter version (if applicable): JupyterLab 0.35.4","author":{"url":"https://github.com/dvincentwest","@type":"Person","name":"dvincentwest"},"datePublished":"2019-01-26T19:51:21.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/13292/matplotlib/issues/13292"}