I have the following data ID x y time 1 10 20 0 1 10 30 1 1 10 40 2 2 12 23 0 2 12 25 1 2 12 28 2 2 12 38 3 3 5 10 0 3 5 15 2 .....
x is time invariant, ID is the subject id number, y is changing over time. I want to find out the difference between the first and last observed y value for each subject and get a table like ID x y 1 10 20 2 12 15 3 5 5 ...... Is there any easy way to generate the data set? [[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.