[R] environments

[Alessio Farcomeni]

>Date: Wed, 30 May 2001 17:40:34 -0400
>From: Setzer.Woodrow at epamail.epa.gov
>Subject: [R] environments
>
>I would like to be able, inside a function, to create a new function, and
>use it as part of a formula as an argument to, say, gnls or nlme.  for
>example:
>
>MyTop <- function(data=dta) {
>     Cexp <- function(dose,A,B,m){...}
>     Model <- as.formula(paste("y","~ Cexp(",paste(formals(Cexp),collapse
>=", "),")"))
>     MyCall <- call("gnls",Model,dta,...)
>     eval(MyCall)
>}
>When I actually try this, I get an error return with the message "Cexp not
>found".  Is there a way around this?  I know I can use "Cexp <<- ...", but
>I'm trying to find a "clean" solution.  Thanks.

I don't have your problems, usually I can define functions inside functions
without problems. Maybe it's the R version... However, perhaps you can
simply define the function Cexp out of MyTop, thus having it visible
"globally". Try this:

Cexp <- function(dose,A,B,m){...}

MyTop <- function(data=dta) {
     Model <- as.formula(paste("y","~ Cexp(",paste(formals(Cexp),collapse
=", "),")"));
     MyCall <- call("gnls",Model,dta,...);
     eval(MyCall)
}

Bye,
Alessio

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