MATLAB: How to find the distance between two non-zero (the element is a one) elements in a matrix

euclidean distanceneighbours

I have a matrix with entries as "1" at random places and i need to find (a) find its non-zero neighbours (b) find the euclidean distance between its non-zero neighbours and the pixel itself

Best Answer

use function pdist from Statistics Toolbox
a = rand(10)<.07
[i1 j1] = find(a);
out = tril(ones(numel(i1)),-1)
out(out~=0) = hypot(pdist(i1),pdist(j1))
OR without pdist
[i1 j1] = find(a);
idx = [i1 j1];
ij = arrayfun(@(ii)tril(bsxfun(@minus,idx(:,ii),idx(:,ii).'),-1),1:2,'un',0);
out = hypot(ij{:})
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