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Re: frozendict

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Date Thu, 9 Feb 2012 10:19:46 -0500
Subject Re: frozendict
From Nathan Rice <nathan.alexander.rice@gmail.com>
To duncan.booth@suttoncourtenay.org.uk
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>> Two dicts created from the same inputs will return items in the same
>> arbitrary order.  As long as you don't insert or delete a key you're
>> fine.
>>
> Two dicts that contain the same keys and values may or may not return them
> in the same order:
>
>>>> dict.fromkeys('ia')
> {'i': None, 'a': None}
>>>> dict.fromkeys('ai')
> {'a': None, 'i': None}
>
> Would your system count those two dicts as the same?
>
> If the sequence in which the keys were added to the dict (and deleted if
> appropriate) is exactly the same then it is likely but still not guaranteed
> that they will have the same order. The only ordering guarantee is that
> within a single dict keys and values will appear in a consistent order so
> long as you don't add/delete keys between calls.

As I said, two dictionaries created from the same input will be the
same...  'ai' != 'ia'.  If I need to hash a dict that I don't know was
created in a deterministic order, I'd frozenset(thedict.items()).


Nathan

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Thread

Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-08 22:43 -0500
  Re: frozendict Duncan Booth <duncan.booth@invalid.invalid> - 2012-02-09 10:33 +0000
    Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 09:36 -0500
      Re: frozendict Duncan Booth <duncan.booth@invalid.invalid> - 2012-02-09 14:52 +0000
        Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 10:19 -0500
          Re: frozendict Duncan Booth <duncan.booth@invalid.invalid> - 2012-02-09 18:47 +0000
        Re: frozendict Ian Kelly <ian.g.kelly@gmail.com> - 2012-02-09 09:35 -0700
          Re: frozendict Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-02-10 01:24 +0000
            Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 21:30 -0500
            Re: frozendict Terry Reedy <tjreedy@udel.edu> - 2012-02-09 22:33 -0500
            Re: frozendict Chris Angelico <rosuav@gmail.com> - 2012-02-10 21:08 +1100
            Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-10 11:53 -0500
            Re: frozendict Chris Rebert <clp2@rebertia.com> - 2012-02-10 09:00 -0800
            Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-10 13:14 -0500
              Re: frozendict John Nagle <nagle@animats.com> - 2012-02-10 10:57 -0800
                Re: frozendict 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-10 21:52 -0800
                Re: frozendict John Nagle <nagle@animats.com> - 2012-02-13 13:15 -0800
        Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 11:50 -0500

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