[R] How sum all possible combinations of rows, given 4 matrices

[Bert Gunter]

Homework? We don't do homework here.

-- Bert

On Mon, May 27, 2013 at 8:24 AM, Estigarribia, Bruno
<estigarr at email.unc.edu> wrote:
> Hello all,
>
> I have 4 matrices with 3 columns each (different number of rows though). I
> want to find a function that returns all possible 3-place vectors
> corresponding to the sum by columns of picking one row from matrix 1, one
> from matrix 2, one from matrix 3, and one from matrix 4. So basically, all
> possible ways of picking one row from each matrix and then sum their
> columns to obtain a 3-place vector.
> Is there a way to use expand.grid and reduce to obtain this result? Or am
> I on the wrong track?
> Thank you,
> Bruno
> PS:I believe I have given all relevant info. I apologize in advance if my
> question is ill-posed or ambiguous.
>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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