bEST is up to you to define. Here is one simple way y.new <- c(t(model.matrix(~factor(y)-1)))
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of zerfetzen Sent: Saturday, November 22, 2008 12:00 PM To: r-help@r-project.org Subject: [R] What's the BEST way in R to adapt this vector? 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, my best guess would be to start as follows: y1 <- ifelse(y == 1, 1, 0) y2 <- ifelse(y == 2, 1, 0) y3 <- ifelse(y == 3, 1, 0) >From here, maybe put these into a 10x3 matrix, and read them out by row >into y.new? Is that even the most efficient way? If it is, I'm sure I can get them into a matrix, but how do I read them out correctly? Thanks for any input. -- View this message in context: http://www.nabble.com/What%27s-the-BEST-way-in-R-to-adapt-this-vector--t p20638991p20638991.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.
