Re: [Rd] Test for argument in ...

From: Gregor Gorjanc <gregor.gorjanc_at_gmail.com>
Date: Sun 02 Jul 2006 - 20:21:48 GMT

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

----------------------------------------------------------------------
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Biotechnical Faculty
Zootechnical Department     URI: http://www.bfro.uni-lj.si/MR/ggorjan
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SI-1230 Domzale             tel: +386 (0)1 72 17 861
Slovenia, Europe            fax: +386 (0)1 72 17 888

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 you have no certainty until you try." Sophocles ~ 450 B.C.

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Received on Mon Jul 03 06:24:52 2006

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