René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ColorbarBase draws edges in slightly wrong positions. ","articleBody":"The code below uses ColorbarBase to print a stacked bar chart of a list of numbers. I use `drawedges=True` to get vertical lines to separate the colors with a black line. The lines are often, not always, slightly misaligned compared to the colors and the tick marks, never more than a few pixels. As I drag the matplotlib window larger and slower you can see these edge lines sometimes rendering correctly (right where the colors change) or just a few pixels off. I _think_ the error is always to the right.\n\nI've attached an example image. If you click the image to see if full scale you'll see a several pixel error at 0.3, and perhaps a 1 pixel error at 0.4. If I drag the window to a different size I can make these errors larger or smaller. \n\nEnvironment:\nWindows 7\nAnaconda Python 3.4, 64 bit installation.\nmatplotlib 1.4.3\nQt graphics back end\n\n```\n    import matplotlib as mpl\n    import matplotlib.pyplot as plt\n\n    a = [.0, .1, .3, .4, 1.]\n    cmap = mpl.colors.ListedColormap([[0., .4, 1.],\n                                      [0., .8, 1.],\n                                      [1., .8, 0.],\n                                      [1., .4, 0.],\n                                      [0., .4, 1.]])\n    fig = plt.figure(figsize=(6,3))\n    ax = fig.add_axes([0.05, 0.475, 0.9, 0.15])\n    norm = mpl.colors.BoundaryNorm(a, cmap.N)\n    mpl.colorbar.ColorbarBase(ax, cmap=cmap,\n                                  norm=norm,\n                                  drawedges=True,\n                                  spacing='proportional',\n                                  orientation='horizontal')\n    plt.show()\n```\n\n![figure_3](https://cloud.githubusercontent.com/assets/5308143/8509644/bd57ecbe-2263-11e5-80f2-401532bc35d9.png)\n","author":{"url":"https://github.com/rlabbe","@type":"Person","name":"rlabbe"},"datePublished":"2015-07-04T22:51:16.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/4584/matplotlib/issues/4584"}