On Tue, May 18, 2010 at 11:00 PM, Gustavo Narea <me@gustavonarea.net> wrote:
I've checked the new collections.Counter class and I think I've found a bug:
from collections import Counter c1 = Counter([1, 2, 1, 3, 2]) c2 = Counter([1, 1, 2, 2, 3]) c3 = Counter([1, 1, 2, 3]) c1 == c2 and c3 not in (c1, c2) True # Perfect, so far. But... There's always a "but": ... len(c1) 3
This is the intended behaviour; it also agrees with what you get when you iterate over a Counter object:
list(c1) [1, 2, 3]
As I understand it, there are other uses for Counter objects besides treating them as multisets; I think the choices for len() and iter() reflected those other uses.
Is this the intended behavior? If so, I'd like to propose a proper multiset implementation for the standard library (preferably called "Multiset"; should I create a PEP?).
Feel free! The proposal should probably go to python-list or python-ideas rather than here, though. See also this recent thread on python-list, and in particular the messages from Raymond Hettinger in that thread: http://mail.python.org/pipermail/python-list/2010-March/thread.html Mark