Try this: outer(y, sort(unique(y)), "==")+0
On Sat, Nov 22, 2008 at 3:37 PM, zerfetzen <[EMAIL PROTECTED]> wrote: > > Goal: > Suppose you have a vector that is a discrete variable with values ranging > from 1 to 3, and length of 10. We'll use this as the example: > > y <- c(1,2,3,1,2,3,1,2,3,1) > > ...and suppose you want your new vector (y.new) to be equal in length to the > possible discrete values (3) times the length (10), and formatted in such a > way that if y[1] == 1, then y.new[1:3] == c(1,0,0), and if y[2] == 2, then > y.new[4:6] == c(0,1,0). For example, the final goal should be: > > y.new <- c(1,0,0,0,1,0,0,0,1,1,0,0,0,1,0,0,0,1,1,0,0,0,1,0,0,0,1,1,0,0) > > Note: I know how to do this with loops, but that's not taking advantage of > R's capabilities with vectors and, I suspect, matrices. > > So far, here's my best: > > y <- c(1,2,3,1,2,3,1,2,3,1) > y.k <- length(unique(y)) #Num. of Categories of y > y.n <- NROW(y) > y.nk <- y.n * y.k #Length of new vector > y.1 <- ifelse(y == 1,1,0) > y.2 <- ifelse(y == 2,1,0) > y.3 <- ifelse(y == 3,1,0) > z <- cbind(y.1, y.2, y.3) > z.trans <- t(z) > y.new <- c(1:y.nk); y.new[1:y.nk] <- NA > y.new <- as.vector(z.trans) > rm(y.k, y.n, y.nk, y.1, y.2, y.3, z, z.trans) > y > y.new > > Is there a better a way? I'm still pretty new. Thanks. > -- > View this message in context: > http://www.nabble.com/What%27s-the-BEST-way-in-R-to-adapt-this-vector--tp20638991p20638991.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. > ______________________________________________ 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.