MATLAB: Matrix buffer

bufferMATLABmatrix

I've got a large matrix, mainly consisting of zeros and with some randomly placed values. I would like to be able to find the surrounding zeros of the non-zero values. If a single value is only surrounded by zeros it's no problem, but a cluster of values poses more problems. I could treat the values in the cluster as single values, but that means an extremely long runtime of the code. Is there a way to find all zeros surrounding a certain value? I don't have any additional toolboxes, but if there is one that could be usefull, I can always try to convince my boss that I need it…

Best Answer

bwdist from Image Processing Toolbox
OR
A - your array
[i1,j1] = find(A)
[y x] = ndgrid(1:size(A,1),1:size(A,2))
out = min(max(abs(bsxfun(@minus,x,reshape(j1,1,1,[]))),...
                                 abs(bsxfun(@minus,y,reshape(i1,1,1,[])))),[],3)
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