[Python-Dev] Retrieve an arbitrary element from a set without removing it

John Arbash Meinel john.meinel at canonical.com
Sun Oct 25 02:47:42 CET 2009

Adam Olsen wrote:
> On Fri, Oct 23, 2009 at 11:04, Vitor Bosshard <algorias at gmail.com> wrote:
>> I see this as being useful for frozensets as well, where you can't get
>> an arbitrary element easily due to the obvious lack of .pop(). I ran
>> into this recently, when I had a frozenset that I knew had 1 element
>> (it was the difference between 2 other sets), but couldn't get to that
>> element easily (get the pun?)
> item, = set_of_one

Interesting. It depends a bit on the speed of tuple unpacking, but
presumably that is quite fast. On my system it is pretty darn good:

0.101us "for x in s: break"
0.112us "x, = s"
0.122us "for x in s: pass"

So not quite as good as the for loop, but quite close.


More information about the Python-Dev mailing list