Column-wise AND operation in all column combinations of two matrices

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Given matrix a of size MxN and matrix b of size MxL I want to get a matrix C of size M x(N*L) which contains the column-wise logical operation AND of all combinations of columns of matrix a and matrix b.
a = [1 0 0
1 0 0
1 0 0
1 0 0
0 1 0
0 1 0
0 1 0
0 1 0
0 0 1
0 0 1
0 0 1
0 0 1];
b= [0 0 1
0 1 0
1 0 0
0 0 1
0 1 0
1 0 0
0 0 1
0 1 0
1 0 0
0 0 1
0 1 0
1 0 0];
C=[];
for ii=1:size(a, 2)
for jj=1:size(b, 2)
C = [C b(:,jj) & a(:,ii)];
end
end
I am searching for an alternative syntax of the above loops. Thank you!

Accepted Answer

Iain
Iain on 24 Feb 2014
This should do it:
C = bsxfun(@and, a, reshape(b,[12,1,3]);
theresult = C(down,column_a,column_b);

More Answers (3)

Azzi Abdelmalek
Azzi Abdelmalek on 24 Feb 2014
out=reshape(repmat(a,size(b,2),1),size(a,1),[]) & repmat(b,1,size(a,2))

Jos (10584)
Jos (10584) on 24 Feb 2014
% Small example: two logical arrays
A = rand(3,3) > .25
B = rand(2,3) > .25
% general engine
[ib,ia] = ndgrid(1:size(B,1), 1:size(A,1))
C = A(ia(:),:) & B(ib(:),:)

Giorgos Papakonstantinou
Giorgos Papakonstantinou on 24 Feb 2014
Thank you all for your replies!!

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