Hi, David, The matrix has 20 columns. Thank you very much for your help. I think it's right, but it seems I need some time to figure it out. I am a green hand. There are so many functions here I never used before. :)
Cindy On Sun, Nov 15, 2009 at 5:19 PM, David Winsemius <dwinsem...@comcast.net>wrote: > Assuming that the number of columns is 4, then consider this approach: > > > prs <-scan() > 1: 2 5 1 6 > 5: 1 7 8 2 > 9: 3 7 6 2 > 13: 9 8 5 7 > 17: > Read 16 items > prmtx <- matrix(prs, 4,4, byrow=T) > > #Now make copus of x.y and y.x > > pair.str <- sapply(1:nrow(prmtx), function(z) c(apply(combn(prmtx[z,], 2), > 2,function(x) paste(x[1],x[2], sep=".")) , apply(combn(prmtx[z,], 2), > 2,function(x) paste(x[2],x[1], sep="."))) ) > tpair <-table(pair.str) > > # This then gives you a duplicated list > > tpair[tpair>1] > pair.str > 1.2 2.1 2.6 2.7 6.2 7.2 7.8 8.7 > 2 2 2 2 2 2 2 2 > > # So only take the first half of the pairs: > > head(tpair[tpair>1], sum(tpair>1)/2) > > pair.str > 1.2 2.1 2.6 2.7 > 2 2 2 2 > > -- > David. > > > > On Nov 15, 2009, at 8:06 PM, David Winsemius wrote: > > I could of course be wrong but have you yet specified the number of >> columns for this pairing exercise? >> >> On Nov 15, 2009, at 5:26 PM, cindy Guo wrote: >> >> Hi, All, >>> >>> I have an n by m matrix with each entry between 1 and 15000. I want to >>> know >>> the frequency of each pair in 1:15000 that occur together in rows. So for >>> example, if the matrix is >>> 2 5 1 6 >>> 1 7 8 2 >>> 3 7 6 2 >>> 9 8 5 7 >>> Pair (2,6) (un-ordered) occurs together in rows 1 and 3. I want to return >>> the value 2 for this pair as well as that for all pairs. Is there a fast >>> way >>> to do this avoiding loops? Loops take too long. >>> >>> and provide commented, minimal, self-contained, reproducible code. >>> >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> >> David Winsemius, MD >> Heritage Laboratories >> West Hartford, CT >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html> >> and provide commented, minimal, self-contained, reproducible code. >> > > David Winsemius, MD > Heritage Laboratories > West Hartford, CT > > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
