Apologies in advance if this is already answered elsewhere, I looked but couldn't find what I needed.
I need to create an ordered id variable by group, so go from a dataset like this:
Data <- data.frame(
group = c("A", "B", "B", "B", "A"),
x = c(1, 2, 3, 4, 5),
y = c(1, 2, 2, 2, 1))
To a dataset like this:
group x y id
1 A 1 1 1
2 B 2 2 1
3 B 3 2 2
4 B 4 2 3
5 A 5 1 2
I know there must be an easy way, but I have not been able to figure it out.
