[R] returning argument names

[Peter Dalgaard BSA]

Michael.Scroggie at nre.vic.gov.au writes:

> Dear r-list folks,
> 
> I have a problem which has been bugging me for a while now and I was hoping
> someone out there might be able to help.
> 
> If I have a user-defined function with an indeterminate number of
> arguments, using the well-known "..." construct, how can I get the
> function to return the names of the items which were the arguments of the
> function as part of the function's output? This is easily done where there
> is a fixed number of arguments: e.g:
> 
> aa<-c(1,2,3,4,5)
> bb<-c(6,7,8,9,10)
> 
> argument.out<-function(object1,object2){
> name1<-deparse(substitute(object1))
> name2<-deparse(substitute(object2))
> output<-c(name1,name2)
> return(output)
> }
> argument.out(aa,bb)
> 
> 
> How can I produce a similar results from a function where there is an indeterminate number of arguments i.e:
> 
> argument.list<-function(object,...){
> 
> Any suggestions or solutions would be much appreciated.

match.call() is your friend. E.g.

 f <- function(...) sapply(as.list(match.call())[-1], deparse)
 f(fee=foo,fie=bar,foe=baz)

actually, as.list is superfluous:

 f <- function(...) sapply(match.call()[-1], deparse)

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907