[R] Again: Variable names in functions

[Peter Dalgaard]

Heinz Tuechler <tuechler at gmx.at> writes:

> > mytable1<-function(x,y){table(x,y)}
> > mytable1(charly, delta)
>    y
> x   1 2
>   1 2 1
>   2 3 4
> If I define the function in the following way, it does what I wish, namely
> it returns output equivalent to the simple call "table(charly, delta)".
> > mytable2<-function(x,y){
> +   cat("table(",as.symbol((deparse(substitute(x)))),
> +   "," ,  as.symbol(deparse(substitute(y))),")\n",
> +   file="temp",sep="",append=F)
> +   eval(parse("temp",n=-1))
> +                       }
> > mytable2(charly, delta)
>       delta
> charly 1 2
>      1 2 1
>      2 3 4
> > 
> I assume that there is a better way to solve this problem and I would be
> happy about hints, where to find solutions in the documentation.

What did Thomas L. say recently? "If the answer involves parse(), you
probably asked the wrong question", I think it was.

The canonical way is

mytable <- function(x,y) eval.parent(substitute(table(x,y)))

or, you could of course modify the names(dimnames(...)) and just pass
the names along.


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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