[R] aggregate arrays

[Leuzinger Sebastian]

Dear list

after quite a bit of research in the archive, I gave up. This seems to be a simple problem:

I would like to aggregate a (3-dimensional) array, either by another array, or by a vector, indicating the dimension which should be aggregated. 

I don't think I have to provide an example, it's really the 3-dimensional equivalent for the standard aggregate command. I am sure aggregate() itself can do it, but how do I need to specify the 'by' argument?

Any hint (also to an earlier post) appreciated

Sebastian