[R] ERP software

Tim Hoar thoar at cgd.ucar.edu
Thu Jul 5 19:50:07 CEST 2001


I think you're missing the point about *realtime* ...

opening and reading a static file is one thing -- having event-driven
reads (i.e. potentially asynchronous reads) directly from the instrument
is another.

I have not tried anything of this sort in R ... sorry.


> Date: Thu, 5 Jul 2001 16:26:23 +0200
> From: Mark M. Span <span at psy.uva.nl>
> To: Bill Simpson <wsi at gcal.ac.uk>
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] ERP software
>
>
> ----- Original Message -----
> From: "Bill Simpson" <wsi at gcal.ac.uk>
> To: "Mark M. Span" <span at psy.uva.nl>
> Sent: Thursday, July 05, 2001 4:02 PM
> Subject: Re: [R] ERP software
>
>
> > No I haven't written any package to do EEG analysis. However I just
> > started some expts with a colleague who uses Matlab for analysis. I will
> > probably convert some of these into R so I can fool around with the data.
> >
> > I know that you can use Matlab to read the incoming data (from
> > the A/D board) directly in realtime. Is that what R-streams is for??
> > It would be handy to be able to use R both for the data collection phase
> > and for the data analysis phase.
> >
> Rstreams reads in binary data (in the non-text meaning of binary). I guess
> most of us (???) have dedicated software for data collection though..
> We use a dataformat that is simple: all the data are written as two-byte
> integers, channelwise.
>
> reading in the data for analysis is a simple
>
>  s <- openstream("U:/d1x001.eeg", "read")
>  dat<-matrix(readint(s, n=33*3000000, size = 2, signed = F, swapbytes =
> FALSE), ncol=33, byrow=T)   # for 33 channel eeg, 3000000 datapoints (R
> complaints about memory here)
>  closestream(s)
>  plot(dat[1:1000,31])  # plot the 31'th channel
>
> The additional software would then cut up the matrix into (a list) of
> trials...
>
> almost looks too easy doesn't it...
> > Cheers,
> > Bill
>
>
>
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## Tim Hoar, Associate Scientist              email: thoar at ucar.edu     ##
## Geophysical Statistics Project             phone: 303-497-1708       ##
## National Center for Atmospheric Research   FAX  : 303-497-1333       ##
## Boulder, CO  80307                    http://www.cgd.ucar.edu/~thoar ##

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