MATLAB: How Detect duplicate value in each column and replace first value with zero

Question

For example

A = [ 5  3  2 5 1 3  1 1 2 2;
      5  8  6 6 1 4  4 2 3 3;
      7  9  9 7 4 8 10 6 4 7;
      8 10 10 9 9 8 10 6 5 7];

In first column 5 duplicate and in five column 1 duplicate I want replace first duplicated values with 0

Answer 1

If your values are always sorted, as in your example, then I believe this will compactly do what you want:

indexToDuplicates = [nan(1,size(A,2));diff(A)]==0;
A(indexToDuplicates) = 0;

You don't even have to split that into two lines, but I thought it might be clearer what I am doing. You could do

A([nan(1,size(A,2));diff(A)]==0) = 0;