MATLAB: Quick method to find duplicates in a matrix

duplicatesloops

Hi guys,

Does anybody know a quick way of checking to see which elements of a matrix are duplicates?

Such as:

a = [1,2,3,4,5,5,1,6,7];

Can we have matlab return the indices of all 1's and 5's or return: 1, 5

Thanks!

You can try:

 [uniqueA i j] = unique(A,'first');
 indexToDupes = find(not(ismember(1:numel(A),i)))

There may be some parameters in the unique() function to get exactly what you desire but i don't remember it off hand.

This should give you the rank you are asking for, Mekala:

   [~,p] = sort(Data,'descend');
   r = 1:length(Data);
   r(p) = r;

'r' will be the ranking.

Here is one way:

[uniqueA i j] = unique(A,'first');
indexToDupes = find(not(ismember(1:numel(A),i)))