Some variation on this?
|:(m,:n) {~"1 |: 4$.$. map
aA
aD
bB
bC
On Tue, 21 Sep 2021, 21:37 bill lam, <[email protected]> wrote:
> Say I have a boolean matrix
> ] map=. 3 4 $ 1 0 0 1 0 1 1 0 0 0 0 0
> 1 0 0 1
> 0 1 1 0
> 0 0 0 0
>
> and 2 vectors of dimension equal to the 2 sides of the matrix
> m=. 'abc' [ n=. 'ABCD'
> I want a cross product for those 1 in the matrix, with result like this
> _2 ]\ 'aAaDbBbC'
> aA
> aD
> bB
> bC
>
> Is it possible to do it without explicit loops? The dimension of the matrix
> can be very large so that generating all cross products then eliminating is
> not an option.
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