On Nov 16, 2009, at 2:32 PM, cindy Guo wrote: > 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.
?order > > 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 > 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 > and provide commented, minimal, self-contained, reproducible code. > > David Winsemius, MD > Heritage Laboratories > West Hartford, CT > > 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.
