[R] Dealing with an argument missing in ...

Achim Zeileis Achim.Zeileis at uibk.ac.at
Wed Mar 10 11:43:50 CET 2010

On Wed, 10 Mar 2010, Christophe Genolini wrote:

> Hi the list
> I define a S3 function that can have a various number of argument using '...'
> When some arguments are missing, I would like to give them some default 
> value:
> func.numeric <- function(x,...){
>  if(missing(y)){y<-3}
> }
> But it does not works...
> I precise that I can not put 'y' explicitly in the argument list since func 
> is an S3 function, I cannot change its arguments.
> Any suggestions?

If the generic func() has arguments "x" and "...", then you can easily 
define a method func.numeric(x, y, ...). Methods need to implement all 
arguments of a generic (including ...) but may add additional argument.


> Thanks
> Christophe
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