[SciPy-user] About alternatives to Matlab

David Cournapeau david at ar.media.kyoto-u.ac.jp
Mon Nov 20 00:36:26 CST 2006

Peter Wang wrote
> Chaco is under very active development, but I do believe it is ready  
> to be used by end users, especially if they don't mind giving much- 
> needed feedback on what docs and additional examples would be most  
> helpful. :)  
My impression was chaco was abandonned, because it was difficult to find 
any information on chaco from google (but this was a few weeks, maybe 
even a few months ago). The precedent emails seem to imply I was wrong, 
and I should check it further.

I understand that chaco is a toolkit to build "scientific" GUI, right ?
> We are using chaco for a lot of internal projects and it  
> works quite well.  What sorts of plots and visualizations were you  
> hoping to put together?
As I said, maybe I've used matplotlib incorrectly, or I didn't spend 
enough time, but I found it really slow (and I have a powerful 
workstation on today's standart), and not really useful interactively; 
also, I often have various threading issues with the python interpreter 
hanging (using ipython with pylab option).

In matlab, you can zoom, edit plots (to remove some lines, for example), 
and I couldn't do that with matplotlib. Again, I cannot stress enough 
that it may just because of my laziness and lack of investigation on 
matplotlib side. Also, I would like to do things that matlab can not do, 
like select data visually, and get the corresponding data back in the 
python interpreter (why matlab does not make this kind of things easy is 
beyond me for such an expensive software), etc...

Something else which would be really great is a (limited) waveform 
editor, something I always dreamt of in matlab. Let's say I have a 10 
second waveform in numpy array: a widget to plot its waveform (which may 
require special interpolation), zoom it horizontaly or vertically, 
select a part of to get the corresponding data... Right now, many 
researchers I know in audio signal processing use something like 
wavesurfer  (http://www.speech.kth.se/wavesurfer/) or an audio editor 
like audacity for the editing/visualization, and matlab for the signal 
processing. This is ackward. Being able to do this kind of visualization 
is one of the reason why I switched to python/numpy/scipy (thinking at 
worse, I could program it from scratch using qt, gtk or whatever toolkit 
available); I haven't taken the time yet to do it.

Having this kind of plot would be really useful, I believe, for people 
doing audio signal processing. Can chaco helps me for this ? Or should I 
investigate further matplotlib ?


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