Tekkaman: If the sublists contain hashable elements you can use this:
def uniter(lists): merge = set() for sub in lists: merge = merge.union(sub) for el in merge: yield el data = [['a', 'b', 'd'], ['b', 'c'], ['a', 'c', 'd']] print list(uniter(data)) But often this too may be enough: def uniter(lists): merge = set() for sub in lists: merge = merge.union(sub) return merge Bye to the gentle Pegas too, bearophile -- http://mail.python.org/mailman/listinfo/python-list