Re: [Matplotlib-users] Plotting speed and error when calling update() using TkAgg

[Thomas C. <tca...@gm...>]

To push much past 20Hz you will want to look into blitting.  See
http://matplotlib.org/devdocs/api/animation_api.html for a rough
introduction on how to use blitting (and see the animation code for an
example of handling all of the corner cases).

Tom

On Fri, Oct 14, 2016 at 5:29 PM Hjalmar Turesson <htu...@gm...>
wrote:

> That works fine. And it explains why update() only worked with the Qt
> backends (I tried all). The speed is still not super impressive though (~20
> fps), but I think I will just start skipping frames when playing at above
> 20 fps.
>
> Thanks,
> Hjalmar
>
> On Fri, Oct 14, 2016 at 10:37 AM, Thomas Caswell <tca...@gm...>
> wrote:
>
> Instead of `canvas.update` call `self.im.figure.canvas.draw_idle()`.
>
> IIRC `update` is part of the API inherited from Qt, not part of the API we
> ensure that all of the canvas objects have.
>
> Tom
>
> On Fri, Oct 7, 2016 at 4:48 PM Hjalmar Turesson <htu...@gm...>
> wrote:
>
> Hi all,
>
>
> I made a little video player using matplotlib. I need it to allow very
> good control over the playback speed (e.g. direction, frame-by-frame
> stepping and fast and slow).
>
> However, it's not very fast. Max frame rate I can achieve is 10-20 fps.
> I followed Basti's advice on speeding up plotting (
> http://bastibe.de/2013-05-30-speeding-up-matplotlib.html).
> This resulted in a more than 2x improvement (from <5 to 10-20 fps), but I
> would like to reach 40-50 fps.
>
> The core code is something like this:
>
> self.im.set_data(self.video_frame)
>
> self.text.set_text('some text')
>
>      self.ax.draw_artist(self.im)
>      self.ax.draw_artist(self.text)
>      self.im.figure.canvas.update()
>      self.im.figure.canvas.flush_events()
>
> video_frame is a 200 x 250 array. I tried lowering dpi from 100 to 50,
> but the improvement is marginal.
>
> I saw that Harden (
> http://www.swharden.com/wp/2013-04-15-fixing-slow-matplotlib-in-pythonxy/)
> recommended using TkAgg over Qt4Agg since TkAgg is supposed to be faster.
> But, TkAgg doesn't play nicely with figure.canvas.update(). I get the
> following error:
> AttributeError: 'FigureCanvasTkAgg' object has no attribute 'update'
> It works with Qt4Agg though.
>
> Does anyone have a fix for this? Or some general advice on how to speed up
> playback speed?
>
> I tried with both matplotlib 1.5.1 and the current version from
> github 2.0.0b4+2373.gb34c55d
>
> Best regards,
> Hjalmar
>
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