[Rd] Test for argument in ...

[Gregor Gorjanc]

Bill Dunlap wrote:
> On Sun, 2 Jul 2006, Gregor Gorjanc wrote:
> 
>> Yes, this works.
>>
>> Thanks Gabor!
>>
>> Gabor Grothendieck wrote:
>>> That's because you are passing the argument twice.  Try this:
>>>
>>>> foo1 <- function(x, ...)
>>> + {
>>> +  L <- list(...)
>>> +  if (is.null(L$decreasing)) L$decreasing <- TRUE
>>> +  do.call(order, c(list(x), L))
>>> + }
>>>> foo1(c(5, 2, 3, 4), decreasing=FALSE)
>>> [1] 2 3 4 1
> 
> How does this differ from
>    foo2 <- function(x, ..., decreasing=TRUE)
>       order(x, ..., decreasing = decreasing)
> ?

I agree, but I wanted to learn ... argument in a more general way. That
was just an example - not a good one as you have showed.

>> x<-c(5,2,3,4)
>> identical(foo2(x), foo1(x))
> [1] TRUE
>> identical(foo2(x,decreasing=F), foo1(x,decreasing=F))
> [1] TRUE
>> identical(foo2(x,decreasing=T), foo1(x,decreasing=T))
> [1] TRUE

-- 
Lep pozdrav / With regards,
    Gregor Gorjanc

----------------------------------------------------------------------
University of Ljubljana     PhD student
Biotechnical Faculty
Zootechnical Department     URI: http://www.bfro.uni-lj.si/MR/ggorjan
Groblje 3                   mail: gregor.gorjanc <at> bfro.uni-lj.si

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