Hi all, Suppose I have the following data.frame, with an id column and two variables columns :
id X Y 0001 NA 21 0002 NA 13 0003 0001 45 0004 NA 71 0005 0003 20 What I would like to do is to create a new variable Z whose values are the Y value for the id value in X, that is : id X Y Z 0001 NA 21 NA 0002 NA 13 NA 0003 0001 45 21 0004 NA 71 NA 0005 0003 20 45 Do you have an idea on how to obtain that without using a for loop ? Thanks in advance for any help, Julien Here is the R code to reproduce the first data.frame : id <- c("0001","0002","0003","0004","0005") x <- c(NA, NA, "0001", NA, "0003") y <- c(21,13,45,71,20) d <- data.frame(id,x,y) -- Julien Barnier Groupe de recherche sur la socialisation ENS-LSH - Lyon, France ______________________________________________ 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.