Tennessee Leeuwenburg wrote: > Now, I know that sets aren't ordered, but... > > foo = set([1,2,3,4,5]) > bar = [1,2,3,4,5] > > foo.pop() will reliably return 1 > while bar.pop() will return 5 > > discuss :)
As designed. If you play around a bit it becomes clear that what set.pop() returns is independent of the insertion order: PythonWin 2.5.2 (r252:60911, Mar 27 2008, 17:57:18) [MSC v.1310 32 bit (Intel)] on win32. >>> foo = set([5,4,3,2,1]) # Order reversed from above >>> foo.pop() 1 >>> foo = set([-1,0,1,2,3,4,5]) >>> foo.pop() 0 >>> foo = set([-1,1,2,3,4,5]) >>> foo.pop() 1 As the documentation says (http://docs.python.org/library/stdtypes.html#set.pop) set.pop() is free to return an arbitrary element. list.pop() however always returns the last element of the list, unless of course you specify some other index: http://docs.python.org/library/stdtypes.html#mutable-sequence-types, point 6. John _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
