Discussion:
[Matplotlib-users] Plotting speed and error when calling update() using TkAgg
Hjalmar Turesson
2016-10-07 20:48:04 UTC
Permalink
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
Thomas Caswell
2016-10-14 14:37:26 UTC
Permalink
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
Post by Hjalmar Turesson
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.
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
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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Hjalmar Turesson
2016-10-14 21:29:18 UTC
Permalink
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
Post by Thomas Caswell
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
Post by Hjalmar Turesson
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.
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
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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Thomas Caswell
2017-01-07 20:36:20 UTC
Permalink
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
Post by Hjalmar Turesson
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
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
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.
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
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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Hjalmar Turesson
2017-04-18 20:50:30 UTC
Permalink
Thanks for the help (and sorry for the super-late reply).

I just tried blitting, but it doesn't really help. I cannot exceed 20 fps.
The problem is that I'm plotting data from a video file, so that for each
frame I need to draw a new array (not just a foreground). I think its just
to much data.

Thanks,
Hjalmar
Post by Thomas Caswell
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
Post by Hjalmar Turesson
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
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
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.
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
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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engaging tech sites, SlashDot.org! http://sdm.link/slashdot______
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Benjamin Root
2017-04-18 21:05:26 UTC
Permalink
I am wondering if the "optimizations" you have are actually slowing you
down. I have never found myself needing to flush_events() or call update()
like that. Or to draw the artists like you are doing. Without seeing more
of the code, it is hard to judge. Have you tried using "runsnakerun" to
profile your code to find out what is actually slowing it down? I can get
60-70Hz without even trying for 3d plotting animations, and that is
probably more computation than this.
Post by Hjalmar Turesson
Thanks for the help (and sorry for the super-late reply).
I just tried blitting, but it doesn't really help. I cannot exceed 20 fps.
The problem is that I'm plotting data from a video file, so that for each
frame I need to draw a new array (not just a foreground). I think its just
to much data.
Thanks,
Hjalmar
Post by Thomas Caswell
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
Post by Hjalmar Turesson
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
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
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.
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/20
13-04-15-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
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
------------------------------------------------------------
------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, SlashDot.org! http://sdm.link/slashdot______
_________________________________________
Matplotlib-users mailing list
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
------------------------------------------------------------
------------------
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engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
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