In this case (Python's collections.Counter[1]), the argument doesn't do what you suggest: you don't return the most common out of the first n items, you return

In this case (Python's collections.Counter[1]), the argument doesn't do what you suggest: you don't return the most common out of the first n items, you return the n most common items. I don't know anything of the specifics of partial sorting but if the argument did what you suggest I'd guess the code would have a line like: # Deal only with the first n items. items = items[:n] As it would make the code much simpler (quoting from The Zen Of Python, "special cases aren't special enough to break the rules"—we don't need a partial sort). [1] http://docs.python.org/library/collections.html#counter-objects http://docs.python.org/library/collections.html#counter-obje...