Is there a more efficient way to do this? def f(L): '''Return a set of the items that occur more than once in L.''' L = list(L) for item in set(L): L.remove(item) return set(L)
|>> f([0, 0, 1, 1, 2, 2, 3]) set([0, 1, 2]) -- http://mail.python.org/mailman/listinfo/python-list