uniq( { OPTIONS }, ele1, ele2, ..., eleN )

uniq() takes a list of elements and returns the unique elements of the list. Each element may be a scalar value or a reference to a list.

If the first element is a hash reference it is taken to be a set of options that alter the way in which the unique filter is applied. The keys of the option set are:

• sort

  If set to a true value, the unique elements of the list will be returned sorted. Perl's default sort will be used unless the compare option is also passed.

  sort defaults to false.

• flatten

  If set to a true value, array references in the list will be recursively flattened, such that

    ( 'foo', [ [ 'bar' ] ], [ [ [ 'baz', 'quux' ] ] ] )
      

  becomes

    ( 'foo', 'bar', 'baz', 'quux' )
      

  flatten defaults to true.

• compare

  A code reference that will be used to sort the elements of the list if the sort option is set. Passing a non-coderef will cause uniq to throw an exception.

  The code ref will be passed a pair of list elements to be compared and should return the same values as the cmp operator.

  Using a custom sort slows things down because the sort routine will be outside of the List::Uniq package. This requires that the pairs to be compared be passed as parameters to the sort routine, not set as package globals (see "sort" in perlfunc). If speed is a concern, you are better off sorting the return of uniq yourself.

The return value is a list of the unique elements if called in list context or a reference to a list of unique elements if called in scalar context.