Dear list member, I have the following data example ke <- data.frame(patid=c(1,1,1,2,3,3),a=c(1,2,2,1,1,2))
I want to add another variable b, such that the max of 'a' by id is returned i.e data ke becomes ke <- data.frame(patid=c(1,1,1,2,3,3),a=c(1,2,2,1,1,2),b=c(2,2,2,1,2,2)) Any help will be appreciated. Oluwakemi [[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.