R help - Jan 2006 - do.call, missing arguments and [

x <- array(1:30, c(4,5,3))
x[1,,]

How can I do the same thing with do.call?

do.call("[", list(x, 1)) == x[1]
do.call("[", list(x, 1, NULL, NULL)) == x[1, NULL, NULL]

I guess you can't, because of the special way that [ deals with arguments.

How can I index an array programmatically for arrays and indices of
varying dimensionality?

Thanks,

Hadley

On 1/18/06, hadley wickham <h.wickham at gmail.com>
wrote:
> x <- array(1:30, c(4,5,3))
> x[1,,]
>
> How can I do the same thing with do.call?
do.call("[", list(x, 1, TRUE, TRUE))

seems to work for me.

Deepayan
>
> do.call("[", list(x, 1)) == x[1]
> do.call("[", list(x, 1, NULL, NULL)) == x[1, NULL, NULL]
>
> I guess you can't, because of the special way that [ deals with
arguments.
>
> How can I index an array programmatically for arrays and indices of
> varying dimensionality?

> do.call("[", list(x, 1, TRUE, TRUE))
>
> seems to work for me.
Oh! Of course.  I knew someone obvious was staring me in the face.

Thanks,

Hadley