On Feb 3, 2012, at 11:45 AM, Leuzinger Sebastian wrote:
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?
Why wouldn't `apply` do what you want? (Which is perhaps my implicit
rebuttal to your suggestion that you don't need to produce an example).
> arr <- array(1:27, c(3,3,3))
> apply(arr, 2:3, mean)
[,1] [,2] [,3]
[1,] 2 11 20
[2,] 5 14 23
[3,] 8 17 26
> apply(arr, 3, mean)
[1] 5 14 23
Any hint (also to an earlier post) appreciated
--
David Winsemius, MD
West Hartford, CT
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