[Python-ideas] exclusively1, common, exclusively2 = set1 - set2, set1 & set2, set2 - set1

[Juancarlo Añez]

On Wed, Jul 3, 2013 at 7:46 PM, Oscar Benjamin
<oscar.j.benjamin at gmail.com>wrote:

> def partition(setx, sety):
>     xonly, xandy, yonly = set(), set(), set()
>     for set1, set2, setn in [(setx, sety, xonly), (sety, setx, yonly)]:
>         for val in set1:
>             if val in set2:
>                 xandy.add(val)
>             else:
>                 setn.add(val)
>     return xonly, xandy, yonly
>


I don't understand why that can be more efficient that using the built-in
operations:

def partition(setx, sety):
    common = setx & sety
    return setx - common, common, sety - common


I assume that the built-in operations traverse over the set with the
smallest size, and preallocate the result to that size.

-- 
Juancarlo *Añez*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20130703/e88b0ef1/attachment-0001.html>