Hope this help: > m <- matrix(c(2,1,3,9,5,7,7,8,1,8,6,5,6,2,2,7),4,4) > p <- c(2, 6)
> apply(m == p[1], 1, any) & apply(m == p[2], 1, any) [1] TRUE FALSE TRUE FALSE If you want the number of rows which contain the pair, sum() could be used: > sum(apply(m == p[1], 1, any) & apply(m == p[2], 1, any)) [1] 2 On Mon, Nov 16, 2009 at 6:26 AM, cindy Guo <cindy.g...@gmail.com> 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. > > Thank you, > > Cindy > > [[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. > ______________________________________________ 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.
