Re: [Matplotlib-users] Efficiently processing large datasets

[John H. <jd...@gm...>]

On Tue, Sep 23, 2008 at 5:56 AM, rfwatson <rfw...@gm...> wrote:
> Hello,
>
> I am using matplotlib in combination with QT4 as part of an audio
> application I am building. Part of this involves plotting an
> oscilloscope-style display (time vs intensity) for sets of raw audio data,
> which I have through necessity converted to arrays of floating point data.
>
> The problem I have is that Pylab/QT slow down an unacceptable amount once
> the amount of audio is more than a few seconds long. This is not too
> surprising - typically a minute of stereo audio data will have 44100 * 60 *
> 2 = 5292000 points. I need to deal with, at minimum, 15 minute clips
> efficiently

Do you typically plot a large number of points, only a subset of which
are in your viewport?  If so, the "clipped line" demo may be useful to
you:

http://matplotlib.sourceforge.net/examples/pylab_examples/clippedline.py

If you are trying to plot a large number of dense points all in the
same viewport, then you will need to decimate the data before
plotting.

JDH