What about: d$var <- c(8, 11, 3, 2)[d$fac]
Side note: it's much appreciated that you included data and a clear problem statement. If you use set.seed(123) before your call to sample(), everyone who tries it will get the same fac that you do. Otherwise we all get something different. Or just generate your own example data and use dput() to include it in your email. Sarah On Thu, Jul 17, 2014 at 11:00 AM, Gang Chen <gangch...@gmail.com> wrote: > Suppose I have the following dataframe: > > L4 <- LETTERS[1:4] > fac <- sample(L4, 10, replace = TRUE) > (d <- data.frame(x = 1, y = 1:10, fac = fac)) > > x y fac > 1 1 1 B > 2 1 2 B > 3 1 3 D > 4 1 4 A > 5 1 5 C > 6 1 6 D > 7 1 7 C > 8 1 8 B > 9 1 9 B > 10 1 10 B > > I'd like to add another column 'var' that is defined based on the > following mapping of column 'fac': > > A -> 8 > B -> 11 > C -> 3 > D -> 2 > > How can I achieve this in an elegant way (with a generic approach for > any length)? > > Thanks, > Gang > -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ 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.
