MATLAB: Elimination of conscutive regions (generalization: ones with zeros between)

consecutiveMATLABvectorization

I don't understand the question, or examples. The "number of consecutive "1's" between "-1's" is what it is. It's determined by A in advance and presumably A was created without regard to any N.
And for the outputs, you are changing the bottom of the middle column even though those 1's are not between ANY -1's. What's the correct rule?

Best Answer

A = [1    -1     0;
     0     1     1;
     0     1     1;
     1     1     0;
     0     0     1;
     1    -1     0;
    -1     1     1;
    -1     0    -1;
     1     1     1;
     0     1    -1];
N = 3;
[m,n] = size(A);
Aclean = A;
for j=1:n
    Aj = [-1; A(:,j); -1];
    i = find(Aj == -1);
    c = histc(find(Aj==1),i);
    b = c <= N;
    im = i(b);
    ip = i([false; b(1:end-1)]);
    a = accumarray(im,1,[m+2,1])-accumarray(ip,1,[m+2,1]);
    mask = cumsum(a);
    mask(i) = 1;
    Aclean(:,j) = Aclean(:,j).*mask(2:end-1);
end
Aclean
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