basic question
sapply(split(test, test$year), function(x) list(x.s = sum(x$x), y.s = sum(x$y), z.s = sum(x$z))) or for one variable only aggregate(test$x, list(id = test$year), sum) cheers christoph
jose silva wrote:
I know this question is very simple, but I am not figure it out I have the data frame: test<- data.frame(year=c(2000,2000,2001,2001),x=c(54,41,90,15), y=c(29,2,92,22), z=c(26,68,46,51)) test year x y z 1 2000 54 29 26 2 2000 41 2 68 3 2001 90 92 46 4 2001 15 22 51 I want to sum the vectors x, y and z within each year (2000 and 2001) to obtain this: year x y z 1 2000 95 31 94 2 2001 105 114 97 I tried tapply but did not work (or probably I do it wrong) Any suggestions? silva [[alternative HTML version deleted]]
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html