uniqueify.R: Looks for duplicate values in a vector and assigns them a unique index in the order in which they appear

test.uniqueify.R

x<-c(4, 1, 1, 3, 5, 3, 2, 4, 2, 5)
y<-uniqueify(x)
 
#x has no "primary key", but (x,y) will uniquely identify values (no duplicates)
cbind(x, y)

uniqueify.R

uniqueify<-function(x) {
	ave(rep.int(1,length(X)), x, FUN=seq_along)
}


old.uniqueify<-function(x) {
	sort.idx<-order(x);
	rev.idx<-order(sort.idx);
	cnts<-rle(x[sort.idx]);
	ids<-unlist(lapply(cnts$lengths, function(x) {seq(1, x)}))
	ids[rev.idx]
}