Dear R-helpers, I have a data frame with 3 variables, each record is a unique combination of the three variables. I would like to count the number of unique values of v3 in each v1, and save it as a new variable v4 in the same data frame. e.g. df1 [v1] [v2] [v3] [1,] "a" "C" "1" [2,] "b" "C" "2" [3,] "c" "B" "3" [4,] "a" "B" "3" [5,] "b" "A" "2" [6,] "c" "A" "1"
In this case, the 4th column would become (2, 1, 2, 2, 1, 2). Could someone tell me how to do this? regards, Lijiang -- [[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.