Set same elements in a matrix to zero

Hi,

I have a large matrix which has duplicate elements in neighborhood.

For example,

A = [0 0 0 01 1 0 0 0 2 2 2 0 0 0 5 5 5 5 5;

0 0 0 1 1 0 0 0 0 0 2 2 0 0 0 5 0 5 0 5;

0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 5 0 5 0]

I have to keep just a unique element in an arbitrary position. Could I use loop to solve this problem?

[Jan]

What is the wanted output for this example?

[WEN SHIN LU]

sorry didn't explain clearly. The output can be:

A = [0 0 0 01 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0;

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 0 0 0 0;

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

I want to keep just one repeated element in its neighborhood.

Answer 1

[Matt J]

Without the Image Processing Toolbox,

A = [0 0 0 0 1 1 0 0 0 2 2 2 0 0 0 5 5 5 5 5;
       0 0 0 1 1 0 0 0 0 0 2 2 0 0 0 5 0 5 0 5;
       0 0 0 0 1 0 0  0 0 0 0 0 0 0 0 0 5 0 5 0]

A = 3×20

0 0 0 0 1 1 0 0 0 2 2 2 0 0 0 5 5 5 5 5 0 0 0 1 1 0 0 0 0 0 2 2 0 0 0 5 0 5 0 5 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 5 0 5 0

[I,J,S]=find(A);


IJS=num2cell(splitapply(@(x) x(1,:), [I,J,S],findgroups(S)),1);

[I,J,S]=deal(IJS{:});

B=accumarray([I,J],S,size(A))

B = 3×20

0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 5 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Answer 2

[Matt J]

Something like this, perhaps?

A = [0 0 0 0 1 1 0 0 0 2 2 2 0 0 0 5 5 5 5 5;
       0 0 0 1 1 0 0 0 0 0 2 2 0 0 0 5 0 5 0 5;
       0 0 0 0 1 0 0  0 0 0 0 0 0 0 0 0 5 0 5 0]

A = 3×20

0 0 0 0 1 1 0 0 0 2 2 2 0 0 0 5 5 5 5 5 0 0 0 1 1 0 0 0 0 0 2 2 0 0 0 5 0 5 0 5 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 5 0 5 0

reg=regionprops(A~=0,'PixelIdxList');

B=zeros(size(A));
for i=1:numel(reg), 
   
    j=reg(i).PixelIdxList(1);
    B(j)=A(j);

end


B

B = 3×20

0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 5 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0