Hi everybody! I'm sure that I overlook something and feel quite stupid to ask, but I have not found an easy solution to the following problem: Take e.g. the Orthodont data from the nlme package:
> head(Orthodont) Grouped Data: distance ~ age | Subject distance age Subject Sex 1 26.0 8 M01 Male 2 25.0 10 M01 Male 3 29.0 12 M01 Male 4 31.0 14 M01 Male 5 21.5 8 M02 Male 6 22.5 10 M02 Male Suppose now, that I have a vector which contains the names of the "meta"-fields in this data-frame: metaFields <- c("Subject", "Sex") I now would like to form a new column "ID" which consists of the columns in metaFields joined like the following: > head(Orthodont) Grouped Data: distance ~ age | Subject distance age Subject Sex ID 1 26.0 8 M01 Male M01/Male 2 25.0 10 M01 Male M01/Male 3 29.0 12 M01 Male M01/Male 4 31.0 14 M01 Male M01/Male 5 21.5 8 M02 Male M02/Male 6 22.5 10 M02 Male M02/Male Any paste commands I tried so far failed, e.g.: Orthodont$ID <- paste(Orthodont[,metaFields], sep="/") is simply wrong. Ok, I could add the columns within a loop to ID, but that is not very elegant. Instead, what I need is a command that in effect produces the output of Orthodont$ID <- paste(Orthodont[,metaFields[1]], Orthodont[,metaFields[2]] , sep="/") There should be some way to do it in R - can someone please enlighten me? Thanks a lot in advance. Greetings, Sebastian ______________________________________________ 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.