Subscript using a 2 column matrix with the rows in the first column and the cols in the 2nd column, e.g.:
> x <- matrix(1:9, 3) > x[ cbind( c(1,2,3), c(3,2,1) ) ] [1] 7 5 3 Hope this helps, -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare [EMAIL PROTECTED] 801.408.8111 > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > project.org] On Behalf Of Werner Wernersen > Sent: Wednesday, October 22, 2008 12:24 PM > To: [EMAIL PROTECTED] > Subject: [R] retrieving matrix elements by giving pairs of row AND > column numbers? > > Hi, > > this is probably a very trivial question but I can't figure out the > right terms to find the solution in the list archive. > > I have a matrix or a data.frame or the like: > > m <- matrix(ncol=3,seq(1,9)) > > m > [,1] [,2] [,3] > [1,] 1 4 7 > [2,] 2 5 8 > [3,] 3 6 9 > > and now I wonder if one can provide somehow two vectors, one containing > row numbers, the other column numbers and thereby retrieve the > corresponding elements? > E.g., providing the 2 vectors c(1,2,3) and c(1,3,1) should return the > matrix values c(1,8,3). > > I ran a couple of times into this problem and always used some awkward > transformations to get around it. > But as I know R, there is probably some slick way to do this. > > Thanks!!! > Werner > > > > > > ______________________________________________ > 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.
