Hi, Also, to make it general:
vec1 <- with(dat,paste(a,b)) within(dat,d <- as.numeric(factor(vec1,labels=seq(length(unique(vec1)))))) #or within(dat,d <- match(vec1,unique(vec1))) #or within(dat,d<- as.numeric(interaction(a,b))) #ids are unique, not in the same order A.K. On Thursday, January 2, 2014 9:30 AM, arun <smartpink...@yahoo.com> wrote: Hi, Try: dat <- read.table(text="a b c 1 1 1 1 1 1 1 1 1 1 2 2 1 2 2 1 2 2 1 3 3 1 3 3 1 3 3 2 1 4 2 1 4 2 1 4 2 2 5 2 2 5 2 2 5 2 2 5",sep="",header=TRUE) within(dat, d <- as.numeric(factor(paste(a,b),labels=1:5))) A.K. On Thursday, January 2, 2014 8:27 AM, Norbi Gurracho <kum...@hotmail.com> wrote: I have a following sample data frame. How can I create a group id of column and b and to obtain column c? a b c 1 1 1 1 1 1 1 1 1 1 2 2 1 2 2 1 2 2 1 3 3 1 3 3 1 3 3 2 1 4 2 1 4 2 1 4 2 2 5 2 2 5 2 2 5 2 2 5 [[alternative HTML version deleted]] ______________________________________________ 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.