Edit: There is something funky about the code. It definitely returns the right column of the "distance" data, but returns an incorrect row.
Code: NCols=250 NRows=829 myMat<-matrix(runif(NCols*NRows), ncol=NCols) d<-dist(myMat) e<-sort.list(d) e<-e[1:5] ##Retrieve minimum 5 distances k <- 5 res <- matrix(NA, ncol = 2, nrow = k) ds <- sort(d) for(i in 1:k) res[i, ] <- which(as.matrix(d) == ds[i], arr.ind = TRUE)[1,] colnames(res) <- c('row','col') rownames(res) <- 1:k res I have derived the formula for 829 rows, to check if the returned column and row matches the index given by e. Column # = x, Row # = y. n = 828-(x-2) index = y+(n+828)(828-n+1)/2 Formula R CODE ##Just checking for row 1 i<-1 y<-res[i,1] x<-res[i,2] n<-(828-(x-2)) index1<-(y+(n+828)*(828-n+1)/2) index2<-e[i] ##index1 should equal index2, but this is not the case ##you can tell that the column is right because index1 & index 2 is close ##(a change in row of 1 shifts the index by 1, but a change in column ## shifts index by ~400 on average) You can then compare this index to the one given by e[i] Jorge Ivan Velez wrote: > > Hi there, > > I am sure there is a better way to do it, but here is a suggestion: > > res <- matrix(NA, ncol = 2, nrow = 5) > for(i in 1:5) res[i, ] <- which(as.matrix(d) == sort(d)[i], arr.ind = > TRUE)[1,] > res > > HTH, > Jorge > > > On Wed, Jun 9, 2010 at 11:30 PM, Jeff08 <> wrote: > >> >> Dear R Gurus, >> >> As you probably know, dist calculates the distance between every two rows >> of >> data. What I am interested in is the actual two rows that have the least >> distance between them, rather than the numerical value of the distance >> itself. >> >> For example, If the minimum distance in the following sample run is >> d[14], >> which is .3826119, and the rows are 4 & 6. I need to find a generic way >> to >> retrieve these rows, for a generic matrix of NRows (in this example >> NRows=7) >> >> NCols=5 >> NRows=7 >> myMat<-matrix(runif(NCols*NRows), ncol=NCols) >> >> d<-dist(myMat) >> >> 1 2 3 4 5 6 >> 2 0.7202138 >> 3 0.7866527 0.9052319 >> 4 0.6105235 1.0754259 0.8897555 >> 5 0.5032729 1.0789359 0.9756421 0.4167131 >> 6 0.6007685 0.6949224 0.3826119 0.7590029 0.7994574 >> 7 0.9751200 1.2218754 1.0547197 0.5681905 0.7795579 0.8291303 >> >> e<-sort.list(d) >> e<-e[1:5] ##Retrieve minimum 5 distances >> >> [1] 14 16 4 18 5 >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/Retrieving-the-2-row-of-dist-computations-tp2249844p2249844.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. >> > > [[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. > > -- View this message in context: http://r.789695.n4.nabble.com/Retrieving-the-2-row-of-dist-computations-tp2249844p2251244.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.