Scott Waichler <[EMAIL PROTECTED]> writes: > I would like to generate a vector having the same length > as the number of rows in a matrix. The vector should contain > an integer indicating the "group" of the row, where identical > matrix rows are in a group, and a unique row has a unique integer. > Thus, for > > a <- c(1,2) > b <- c(1,3) > c <- c(1,2) > d <- c(1,2) > e <- c(1,3) > f <- c(2,1) > mat <- rbind(a,b,c,d,e,f) > > I would like to get the vector c(1,2,1,1,2,3). I know dist() gives > part of the answer, but I can't figure out how to use it for > this purpose without doing a lot of looping. I need to apply this > to matrices up to ~100000 rows.
I believe you want to start with unique which, when applied to a matrix, provides the unique rows. > unique(mat) [,1] [,2] a 1 2 b 1 3 f 2 1 I'm sure others will be able to provide clever ways of doing the matching against the unique rows. ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
