2009/2/23 Λεωνίδας Μπαντής <bleonida...@yahoo.gr>: > > Hi there, > > I am pretty new to R. Actually I started using it yesterday. I have two > questions: > > 1. Suppose I have a<-c(1:10) (or a<-array(c(1:10),dim=c(1,10))) > > and I want to end up with vector b=[0 0 0 0 0 1 1 1 1 1]. i.e. I want to > substitute alla elements that are <5 with 0 and >5 with 1. > > I did this by using a for loop. Is there another function to use so as to > avoid the "for"?
(a>5)+0 # or out <- as.numeric(a > 5) if (is.matrix(a)) out <- matrix(a, 1) out > > > 2. Suppose I have a<-c(1,1,2,2,3,3) (or array again) > > And I want to place a "4,5" before every "2" and end up with a new "bigger" > vector "b": > > b=[1 1 4 5 2 4 5 2 3 3] # return c(4, 5, 2) or x f <- function(x) if (x==2) c(4:5, x) else x # apply f to each element and # if a is a matrix make output a matrix too out <- unlist(sapply(a, f)) if (is.matrix(a)) out <- matrix(out, nrow(a)) out > > Also I want to find where the 2's in array "a" (if it was an array) are > located i.e. positions 3,4. which(a == 2) ______________________________________________ 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.