> It isn't quite convenient to read the data posted below into R > (if it was originally tab-separated, that formatting got lost) but > ddply from the plyr package is good for this: something like (untested) > > d <- with(data,ddply(data,interaction(UniqueID,Reason), > function(x) { > ## make sure x is sorted by date/time here > x$F_R <- c("F",rep("R",nrow(x)-1)) > x > })
Or a little more succinctly: d <- ddply(data, c("UniqueID", "Reason"), transform, F_R = c("F",rep("R",nrow(x)-1)) Hadley -- Assistant Professor / Dobelman Family Junior Chair Department of Statistics / Rice University http://had.co.nz/ ______________________________________________ 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.