On 17/11/2007 5:04 PM, Johannes Hüsing wrote:
> Dear expRts,
> I just realized that the "..." argument in a function cannot be used without
> taking precautions sometimes. The following behaviour is what I stumbled
> upon:
The problem is the way replicate is implemented. It takes the
expression, and wraps it in a function(...) before calling sapply. The
... in your expression matches the ... in the wrapper function, not the
... from the parent.
I think you'll need to make calls to sapply directly to do what you want.
Duncan Murdoch
>
>> myrepl <- function(length, fun, ...) {
> + replicate(length, fun(...))}
>> myrepl(20, sample, 1:5)
> [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>> myotherrepl <- function(length, fun, ...) {
> + args <- list(...)
> + replicate(length, do.call(fun, args))}
>> myotherrepl(20, sample, 1:5)
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13]
> [,14]
> [1,] 1 2 3 4 3 1 5 4 1 3 1 1 5
> 2
> [2,] 5 4 1 1 1 2 4 3 5 4 2 3 4
> 3
> [3,] 3 3 2 2 2 5 2 5 2 2 5 2 3
> 5
> [4,] 4 5 5 3 5 4 1 1 3 5 4 4 1
> 4
> [5,] 2 1 4 5 4 3 3 2 4 1 3 5 2
> 1
> [,15] [,16] [,17] [,18] [,19] [,20]
> [1,] 4 5 1 2 5 5
> [2,] 2 1 4 1 1 4
> [3,] 3 3 2 3 3 3
> [4,] 1 4 3 5 4 2
> [5,] 5 2 5 4 2 1
>
> Is the necessity to protect "..." unique to replicate(), or have I been
> (or am I still) missing something basic here?
>
> Best wishes
>
>
> Johannes
>
>
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>
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