MATLAB: Storing the positions of neighbouring elements that have specific values.

findindexingmatrix

A = zeros(5,5);
A(3,4)=1;
A(4,1)=1
I have a matrix of zeros with two 1's in postions (3,4) and (4,1). Starting with the 1 at (3,4) I want to store all the positions of neighbouring elements that are eqaul to 0. I want to do this as my next step is to choose one of the neighbours that equal 0, change that to a 1, and then start the whole process again, starting at any element that equals 1.

Best Answer

>> i0=3; j0=4;
>> [i,j]=find(~A(i0-1:i0+1,j0-1:j0+1));
>> [i,j]
ans =
          1.00          1.00
          2.00          1.00
          3.00          1.00
          1.00          2.00
          3.00          2.00
          1.00          3.00
          2.00          3.00
          3.00          3.00
>>
You'll have to restrict search to either include only interior initial points or modify to account for location on boundary in computing range vectors.
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