Dear R Helpers, I'm struggling with a data preparation problem. I feel that it is a quite easy task but I don't get it done. I hope you can help me with that.
I have a data frame looking like this: ID <- c(1,1,1,2,2,3,3,3,3) T <- c(1,2,3,1,4,3,5,6,8) x <- rep(1,9) df <- data.frame(ID,T,x) >df ID T x 1 1 1 1 2 1 1 3 1 2 1 1 2 4 1 3 3 1 3 5 1 3 6 1 3 8 1 I want to manipulate the x column in a way that for each customer (ID) at the minimum of T the x value is set to zero. The result should look like this: ID T x x_new 1 1 1 0 1 2 1 1 1 3 1 1 2 1 1 0 2 4 1 1 3 3 1 0 3 5 1 1 3 6 1 1 3 8 1 1 I already tried the aggregate() and apply() function, but I don't get the result I'm looking for. I would glad if you could help me out. Best regards, Carlos [[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.