[Eeglablist] How to make an ICA run in less than a week?

[C Kalfaoglu]

Hi James,
I had the same problem with running ICA on continuous data from 128 
channel biosemi data. My solution was to down-sample the data from 
2048Hz to 512Hz or 256Hz before running the ICA. Assuming the high 
sampling rate is not crucial for your purposes, you can get ICA 
completed overnight (definitely at 256Hz).

EEGLAB experts can advise more on the effect of sampling rate on ICA 
resolution, but I have got quite robust results with 256Hz data.

C


On 07/07/12 01:40, Stephen Politzer-Ahles wrote:
> Hi James,
> I've never run ICA on continuous data so I don't have a feeling for 
> how long yours should be taking; but one thing you can do that I 
> imagine will sped things up significantly is to epoch the dataset, if 
> that is an option for you; my understanding is that, while running ICA 
> on continuous data is the best, you can still get acceptable 
> decompositions from epoched data if your epochs are big enough and not 
> too noisy.
> There are also some other algorithms available, like fastica and 
> binica, that are supposed to be faster; I've never tried them so I'm 
> not sure what the other consequences of using those rather than runica 
> might be.
> Best,
> Steve
>
> On Fri, Jul 6, 2012 at 8:24 AM, James Schaeffer <schaefj3 at gmail.com 
> <mailto:schaefj3 at gmail.com>> wrote:
>
>     Dear eeglablist,
>
>     I am running ICAs on 10 minutes of Biosemi EEG data, collected
>     from 128 channels, and sampled at 2048 Hz. However, the ICAs have
>     been running for a few days without much progress. Two computers
>     have 8G RAM and an Intel(R) Xeon(TM) CPU 2.80GHz. One has been
>     running an ICA for 6 days and is on step 33; the other, for 4
>     days, and is on step 28. Another computer has 12G RAM and an
>     Intel(R) Xeon(R) CPU 5110 @ 1.60GHz; it has been running for 3
>     days and is on step 60. All are running openSUSE 12.1 (x86_64),
>     with eeglab version 10.2.2.4b. The 'free' command indicates that
>     they are not using any swap space.  Should it be taking this long?
>     Is it possible that we have more than the one copy of the data in
>     ram or that Matlab or Eeglab has placed something else in ram, or
>     is busy with other processes? Is there anything I can do to speed
>     up this process? Any help would be greatly appreciated.
>
>     Thanks in advance,
>     James
>
>
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>
>
> -- 
> Stephen Politzer-Ahles
> University of Kansas
> Linguistics Department
> http://www.linguistics.ku.edu/
>
>
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