René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Different result, slower runtime of heatmap between 2.0.0 and 2.0.1","articleBody":"### Bug report\r\n\r\n**Bug summary**\r\n\r\nI am using Matplotlib with Basemap to create heatmaps of data.\r\nA change introduced between version 2.0.0 and 2.0.1 caused my code to:\r\n* Produce a different result\r\n* Run significantly slower\r\n\r\nThe problem still seems to exist in 2.0.2.\r\n\r\nI also ran some profiling to have a look at the differences, and the increase in time seems to be in the `resample` function (from 0.473s total time to 19.042s total time)\r\n\r\n**Code for reproduction**\r\n\r\n```python\r\nimport csv\r\nimport time\r\n\r\nimport numpy as np\r\nimport matplotlib\r\nimport matplotlib.pyplot as plt\r\nimport matplotlib.cm as cm\r\nfrom mpl_toolkits.basemap import Basemap\r\n\r\n\r\ndef create_basemap():\r\n    m = Basemap(projection='cyl', llcrnrlat=-90, urcrnrlat=90,\r\n                llcrnrlon=-180, urcrnrlon=180, resolution='c')\r\n    m.drawmapboundary(fill_color='#b4d0d0')\r\n    m.drawcoastlines(linewidth=0.25, color=\"#ffffff\")\r\n    m.fillcontinents(color=\"grey\", lake_color='#b4d0d0')\r\n\r\n    m.drawparallels(np.arange(-90., 91., 30.), linewidth=\"0.25\", color=\"#333333\")\r\n    m.drawmeridians(np.arange(-180., 181., 60.), linewidth=\"0.25\", color=\"#555555\")\r\n    return m\r\n\r\n\r\ndef create_heatmap(positions):\r\n    heatmap = np.zeros((180, 360))\r\n    extents = [[-90, 90], [-180, 180]]\r\n\r\n    lats, lons = map(list, zip(*positions))\r\n\r\n    subheatmap, xedges, yedges = np.histogram2d(lats, lons, bins=[180, 360], range=extents)\r\n    extent = [xedges[0], xedges[-1], yedges[0], yedges[-1]]\r\n    heatmap = np.add(heatmap, subheatmap)\r\n\r\n    fig = plt.figure()\r\n    m = create_basemap()\r\n\r\n    cmap = cm.jet\r\n    cmap.set_bad(alpha=0.0)\r\n\r\n    im = m.imshow(heatmap, cmap=cmap, interpolation='bicubic', extent=extent, origin='lower', alpha=1.0, norm=matplotlib.colors.LogNorm(), vmin=1, vmax=2, zorder=100)\r\n    cb = fig.colorbar(im, shrink=0.5, format=\"%d\")\r\n\r\n    plt.title(\"Test\")\r\n    plt.savefig(\"test.png\", dpi=500, bbox_inches='tight', pad_inches=0.1)\r\n    plt.close()\r\n\r\n\r\npositions = [(50, i) for i in range(50)]\r\nstart = time.time()\r\ncreate_heatmap(positions)\r\nprint \"Runtime: {0}\".format(time.time() - start)\r\n```\r\n\r\n**Version 2.0.0 outcome**\r\n\r\n```\r\nRuntime: 2.31200003624\r\n```\r\n![2 0 0](https://user-images.githubusercontent.com/8438951/28690404-0c940b66-72e7-11e7-8589-de72d04283e2.png)\r\n\r\n`python -m cProfile --sort=tottime script.py`:\r\n```\r\n         667764 function calls (659117 primitive calls) in 3.555 seconds\r\n\r\n   Ordered by: internal time\r\n\r\n   ncalls  tottime  percall  cumtime  percall filename:lineno(function)\r\n        2    0.702    0.351    0.702    0.351 {matplotlib._png.write_png}\r\n        2    0.473    0.237    0.473    0.237 {matplotlib._image.resample}\r\n        1    0.138    0.138    0.138    0.138 {_tkinter.create}\r\n      890    0.117    0.000    0.117    0.000 {method 'is_valid' of '_geoslib.BaseGeometry' objects}\r\n       15    0.106    0.007    0.632    0.042 __init__.py:1(\u003cmodule\u003e)\r\n        1    0.090    0.090    0.135    0.135 __init__.py:14(\u003cmodule\u003e)\r\n      296    0.083    0.000    0.083    0.000 {method 'intersection' of '_geoslib.BaseGeometry' objects}\r\n        2    0.068    0.034    0.681    0.340 image.py:275(_make_image)\r\n    11413    0.055    0.000    0.058    0.000 {numpy.core.multiarray.array}\r\n      300    0.050    0.000    0.072    0.000 {method 'draw_path' of 'matplotlib.backends._backend_agg.RendererAgg' objects}\r\n...\r\n```\r\n\r\n**Version 2.0.1 outcome**\r\n```\r\nRuntime: 21.0169999599\r\n```\r\n![2 0 1](https://user-images.githubusercontent.com/8438951/28690462-4f7640a2-72e7-11e7-8688-4d9f7c729cf3.png)\r\n\r\n`python -m cProfile --sort=tottime script.py`:\r\n```\r\n         1763720 function calls (1754827 primitive calls) in 23.725 seconds\r\n\r\n   Ordered by: internal time\r\n\r\n   ncalls  tottime  percall  cumtime  percall filename:lineno(function)\r\n        4   19.042    4.761   19.043    4.761 {matplotlib._image.resample}\r\n        2    0.735    0.367    0.735    0.367 {matplotlib._png.write_png}\r\n        2    0.609    0.304    1.377    0.688 font_manager.py:558(createFontList)\r\n       60    0.138    0.002    0.336    0.006 afm.py:181(_parse_char_metrics)\r\n        1    0.135    0.135    0.135    0.135 {_tkinter.create}\r\n        2    0.133    0.067   19.309    9.655 image.py:275(_make_image)\r\n      890    0.115    0.000    0.115    0.000 {method 'is_valid' of '_geoslib.BaseGeometry' objects}\r\n        1    0.107    0.107    0.159    0.159 __init__.py:14(\u003cmodule\u003e)\r\n       15    0.106    0.007    0.637    0.042 __init__.py:1(\u003cmodule\u003e)\r\n      559    0.104    0.000    0.104    0.000 {method 'get_sfnt' of 'matplotlib.ft2font.FT2Font' objects}\r\n```\r\n\r\n**Matplotlib version**\r\n  * Operating System: Windows 10\r\n  * Matplotlib Version: 2.0.0/2.0.1 (from pip)\r\n  * Python Version: 2.7.13\r\n  * Jupyter Version (if applicable): N/A\r\n  * Other Libraries: basemap 1.1.0, numpy 1.13.1\r\n\r\n","author":{"url":"https://github.com/NickG123","@type":"Person","name":"NickG123"},"datePublished":"2017-07-27T20:31:33.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/8947/matplotlib/issues/8947"}