[R] How to make a 2-dim array being "interpreted" as an array rather than as a matrix

[Henrique Dallazuanna]

I don't know if is the best way:

a3 <- array(a2, dim=c(nrow(a2), ncol(a2), 1))

foo(a3)

On 04/03/2008, Søren Højsgaard <Soren.Hojsgaard at agrsci.dk> wrote:
> Dear List
>
>  A 2-dimensional array seems to be "interpreted" as a matrix whereas higher dimensional arrays are interpreted as arrays, e.g.
>
>  > a1 <- array(1:8,c(2,2,2))
>  > class(a1)
>  [1] "array"
>  > a2 <- array(1:4,c(2,2))
>  > class(a2)
>  [1] "matrix"
>
>  If I write a generic function (apologies if this is the wrong word) on arrays as
>
>  foo <- function(x) UseMethod("foo")
>  foo.array <- function(x) sum(x)
>
>  then this fails on a 2-dimensional array:
>
>  > foo(a1)
>  [1] 36
>  > foo(a2)
>  Error in UseMethod("foo") : no applicable method for "foo"
>
>  Is there any way in which I can "force" a2 to being "interpreted" as having class "array" rather than "matrix" so that foo will work on a2???
>
>  Thanks in advance
>  Søren
>
>
>
>
>
>
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O