Dear all, I have a data set as follows: ID cycle.number cycle.result 1 2525 1 38 2 2525 2 38 3 2525 3 25 4 2525 4 25 5 2525 5 25 6 2525 6 25 7 2531 1 38 8 2531 2 38 9 2078 1 38 10 2078 2 38
I want to find out the maximum cycle.number for each ID, and later find the corresponding cycle.result for that cycle. I have already managed to pull out the maximum cycle by using a for loop: max.cycle <- vector() patients <- (levels(factor(ID))) for (i in 1:length(patients)) { max.cycle[i] <- max(cycle.number[(ID %in% patients[i] )]) } But i would like to know if there is a better or more elegant way of pulling out the maximum cycle.number for each ID? Perhaps without the need for using a for loop? Many thanks, Caroline [[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.