I forgot to say that there are no ties in each row. So any number can occur only once in each row. Also as I mentioned earlier, actually I only need the top 50 most frequent pairs, is there a more efficient way to do it? Because I have 15000 numbers, output of all the pairs would be too long.
Thank you, Cindy On Mon, Nov 16, 2009 at 7:02 AM, David Winsemius <dwinsem...@comcast.net>wrote: > I stuck in another "7" in one of the lines with a 2 and reasoned that we > could deal with the desire for non-ordered "pair counting" by pasting > min(x,y) to max(x,y); > > > dput(prmtx) > structure(c(2, 1, 3, 9, 5, 7, 7, 8, 1, 7, 6, 5, 6, 2, 2, 7), .Dim = c(4L, > 4L)) > > prmtx > [,1] [,2] [,3] [,4] > [1,] 2 5 1 6 > [2,] 1 7 7 2 > [3,] 3 7 6 2 > [4,] 9 8 5 7 > > > pair.str <- sapply(1:nrow(prmtx), function(z) apply(combn(prmtx[z,], 2), > 2,function(x) paste(min(x[2],x[1]), max(x[2],x[1]), sep="."))) > > The logic: > sapply(1:nrow(prmtx), ... just loops over the rows of the matrix. > combn(prmtx[z,], 2) ... returns a two row matrix of combination in a > single row. > apply(combn(prmtx[z,], 2), 2 ... since combn( , 2) returns a matrix that > has two _rows_ I needed to loop over the columns. > paste(min(x[2],x[1]), max(x[2],x[1]), sep=".") ... stick the minimum of a > pair in front of the max and separates them with a period to prevent two+ > digits from being non-unique > > Then using table() and logical tests in an index for the desired multiple > pairs: > > > > tpair <-table(pair.str) > > tpair > pair.str > 1.2 1.5 1.6 1.7 2.3 2.5 2.6 2.7 3.6 3.7 5.6 5.7 5.8 5.9 6.7 7.7 7.8 7.9 8.9 > 2 1 1 2 1 1 2 3 1 1 1 1 1 1 1 1 1 1 1 > > > tpair[tpair>1] > pair.str > 1.2 1.7 2.6 2.7 > 2 2 2 3 > > -- > David. > > > On Nov 16, 2009, at 7:02 AM, David Winsemius wrote: > > I'm not convinced it's right. In fact, I'm pretty sure the last step taking >> only the first half of the list is wrong. I also do not know if you have >> considered how you want to count situations like: >> >> 3 2 7 4 5 7 ... >> 7 3 8 6 1 2 9 2 ...... >> >> How many "pairs" of 2-7/7-2 would that represent? >> >> -- >> David >> On Nov 15, 2009, at 11:06 PM, cindy Guo wrote: >> >> 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 >>> >>> >>> >> 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.
