On Thu, 2006-11-30 at 21:10 +0100, Carmen Meier wrote: > Hi to all > I did not found the right hints for functions with the dot-dot-dot argument. > Is it possible to write own functions with the tree dots and if yes > what's wrong with the following example? > > > test <- function(x, ...) > { > print (x) > if (exists("y"))print(y) > if (exists("z"))print(z) > } > > test(4,y=2) > > With regards Carmen Carmen,
The problem is that 'y' and 'z' don't exist as R objects, so the result of both tests is FALSE. Try this: test <- function(x, ...) { print(x) dotargs <- list(...) if ("y" %in% names(dotargs)) print(dotargs$y) if ("z" %in% names(dotargs)) print(dotargs$z) } > test(4) [1] 4 > test(4, y = 2) [1] 4 [1] 2 > test(4, y = 2, z = 3) [1] 4 [1] 2 [1] 3 HTH, Marc Schwartz ______________________________________________ R-help@stat.math.ethz.ch 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.