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

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