Percentile for Each Observation w/r/t Grouping Variable

Question

I have some data that looks like the following. It is grouped by variable \"Year\" and I want to extract the percentiles of each observation of Score, with respect to t

Answer 1

How about something like:

Year <- c(2000,2008,2008,2000,2000)
Fees <- c(1000,1050,2000,1700,2000)
dat <- data.frame(Fees,Year,result=NA)
res <- tapply(Fees,Year,function(x) rank(x,ties.method="max")/length(x))
for(i in 1:length(res))
   dat[Year==as.numeric(names(res)[i]),"result"] <-res[[i]]

which yields:

  Fees Year    result
1 1000 2000 0.3333333
2 1050 2008 0.5000000
3 2000 2008 1.0000000
4 1700 2000 0.6666667
5 2000 2000 1.0000000