findduplicates, a MATLAB function to find linear indices of duplicates in input

This function accepts the same input arguments as the unique function, which is the basis for this function. findduplicates has two output arguments, i1 and i2.

Syntax

[i1,i2] = findduplicates(A,__) finds the linear indices of duplicates in input A. The accepted input arguments are the same as accepted by the unique function. The first output, i1, contains the linear indices of the first duplicate elements into A that correspond to the duplicates indexed by i2, the second output. i1 may contain the same index multiple times if an element exists more than twice in A. If no duplicates exist, i1 and i2 are returned empty.

Examples

Run findduplicatesdemo for a demonstration of findduplicates. See the contents of findduplicatesdemo.m for details.

Notes

• The 'stable' flag of the unique function has no functionality in findduplicates, but is allowed for compatibility.
• NaN are considered as non-unique by the unique function, thus they are considered non-duplicates by findduplicates as well.
• For completeness the third, fourth and fifth outputs are the three output arguments of the unique function. Use them as follows: [i1,i2,C,ia,ic] = findduplicates(__).