Re: [R] Functions within functions in R and S-Plus

From: Sundar Dorai-Raj <sundar.dorai-raj_at_pdf.com>
Date: Wed 08 Jun 2005 - 03:11:54 EST

Victor Gravenholt wrote:
> Sorry to bother you about a S-Plus related problem, but I hope someone
> can help.
> I have tried to "translate" some code from R to S-Plus (I have colleague
> that insists on using S-Plus. And yes, I have tried to make him change
> to R...)
> The following code works out fine in R, but in S-Plus (S-PLUS 6.2 for
> Windows Professional Ed.) I get the error message "Problem in
> est.theta(x): Object "func" not found ".
> I have tried to keep most of the structure in my original problem (but
> simplified it!), so the code could seem a bit strange.
> I suspect that this has something to do with different scoping rules in
> R and S-Plus, but still I have not found a workable solution in S-Plus.
>
> mainfunc <- function(x){
>
> est <- function(x,par){
> abs(sum(par*x))
> }
>
> func <- function(par,x){
> est(x,par)
> }
>
> est.theta <- function(x){
> optimize(func,lower=-10, upper=20,x=x)$minimum
> }
>
> est.theta(x)
>
> }
>
> x <- 1:10
> mainfunc(x)
>
>
>

You need to supply func to est.theta. R uses scoping to find func and est. S-PLUS scoping is defined differently and cannot, so you must assign them to the current frame.

is.R <- !is.null(version$language)
mainfunc <- function(x) {

   est <- function(x, par) {
     abs(sum(par * x))
   }
   func <- function(par, x) {
     est(x, par)
   }
   est.theta <- function(x) {
     optimize(func, lower = -10, upper = 20, x = x)$minimum    }
   if(!is.R) {

     assign("func", func, frame = 1)
     assign("est", est, frame = 1)

   }
   est.theta(x)
}
mainfunc(1:10)

--sundar



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