I think you'll have to code it a bit different. I'd do :
f <- function(x,y){
if(missing(y)) y <-x
x+y
}
> f(2)
[1] 4
> f(2,3)
[1] 5
>

On Tue, May 4, 2010 at 4:26 PM, Thorn <thorn.thaler@rdls.nestle.com> wrote:

> Hi everybody,
>
> how is it possible to refer to an argument passed to a function in the
> function call? What I like to do, is something like
>
> f <- function(x,y) x+y
> f(2, x) # should give 4
>
> The problem is of course that x is only known inside the function. Of
> course I
> could specify something like
>
> f(z<-2,z)
>
> but I'm just curious whether it is possible to use a fancy combination of
> eval, substitute or quote ;)
>
> BR, thorn
>
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



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