René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Qt4Agg backend changes figure size","articleBody":"Edit: Note that this issue is also still present with Qt5Agg and matplotlib 3.0.1\r\n\r\nShowing a figure with Qt4Agg backend changes the figure size. This is observed with Windows 8.1, python 2.7, matplotlib 2.1.\r\n\r\n```\r\nimport matplotlib\r\nmatplotlib.use(\"Qt4Agg\")\r\nimport matplotlib.pyplot as plt\r\n\r\nfig, ax = plt.subplots()\r\nax.plot([1,2,4])\r\n\r\ndef update(evt):\r\n    print(fig.get_size_inches())\r\n       \r\ncid = fig.canvas.mpl_connect(\"key_press_event\", update)\r\n\r\nprint(fig.get_size_inches())\r\nplt.show()\r\n```\r\nThe original figure is `[ 6.4  4.8]`. After the figure is drawn (and in this case you press a key), it is only `[ 6.4   4.78]`.  \r\nOne could argue that this is only a small amount, but saving the figure from within the event loop now gives a different figure size of the saved figure. To make this more obvious, consider the following code which saves a new image after each press of space.\r\n\r\n```\r\nimport matplotlib\r\nmatplotlib.use(\"Qt4Agg\")\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\nclass NextPlotter(object):\r\n    def __init__(self, fig, func, n):\r\n        self.__dict__.update(locals())\r\n        self.i = 0\r\n        self.cid = self.fig.canvas.mpl_connect(\"key_press_event\", self.adv)\r\n        \r\n    def adv(self, evt):\r\n        if evt.key == \" \" and self.i \u003c self.n:\r\n            self.func(self.i)\r\n            self.i+=1\r\n        elif self.i \u003e= self.n:\r\n            plt.close(\"all\")\r\n\r\n# Create data\r\npos = range(8)\r\nscatterdata = np.random.normal(0, 5, size=(50,len(pos)))\r\n\r\n#Create plot\r\nfig, ax = plt.subplots()\r\nax.axis([-10,10,-10,10])\r\nscatter = ax.scatter([], [], c=\"crimson\", s=60)\r\n\r\n# define updating function\r\ndef update(i):\r\n    print(\"++ update \" + str(i))\r\n    scatter.set_offsets(np.c_[pos,scatterdata[i,:]])\r\n    fig.canvas.draw()\r\n    print(fig.get_size_inches())\r\n    plt.savefig(\"plot_{i}.png\".format(i=i))\r\n    print(fig.get_size_inches())\r\n\r\n# instantiate NextPlotter; press \u003cspace\u003e to advance to the next image        \r\nc = NextPlotter(fig, update, len(scatterdata))\r\n\r\nplt.show()\r\n```\r\nresulting in \r\n![nextplotter_qtagg3](https://user-images.githubusercontent.com/23121882/33517240-c672a602-d780-11e7-90ae-593c89e736ce.gif)\r\n\r\nIs this a problem of PyQt4? Can anyone reproduce this outside of Windows 8? ","author":{"url":"https://github.com/ImportanceOfBeingErnest","@type":"Person","name":"ImportanceOfBeingErnest"},"datePublished":"2017-12-02T15:53:59.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":20},"url":"https://github.com/9913/matplotlib/issues/9913"}