How can I tell if a rectangular matrix has duplicate rows in MATLAB?

Question

I have an n-by-m rectangular matrix (n != m). What\'s the best way to find out if there are any duplicate rows in it in MATLAB? What\'s the best way to find the indices of t

Answer 1

Say your matrix is M:

[S,idx1] = sortrows(M);
idx2 = find(all(diff(S,1) == 0,2));
out = unique(idx1([idx2;idx2+1]));

out will contain the duplicate row indices if any.