[R] efficient filtering of matrices

From: <sms13+_at_pitt.edu>
Date: Fri 06 May 2005 - 04:05:58 EST


I was wondering if someone can tell me the best way to search through a matrix and choose certain rows (based on certain conditions) to put into a separate matrix.
What I have tried so far is very slow for a large dataset I'm working with. e.g., I have this piece of code to create a new matrix (newmat) based on my filtering conditions. Do I need to do this kind of thing where I keep rbinding?

newmat<-rep(NA,12)
for (i in 1:length(origmat[,1])
{

        if ( is.na(origmat[i,10]) | (!is.na(origmat[i,10]) & (origmat[i,2] <= origmat[i,10]) ) )

                newmat<-rbind(newmat, origmat[i,])
}

Thanks,
Steven



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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri May 06 04:13:55 2005

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