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Groups > comp.lang.python > #26825
| Date | 2012-08-09 18:26 -0400 |
|---|---|
| From | Dave Angel <d@davea.name> |
| Subject | Re: save dictionary to a file without brackets. |
| References | (2 earlier) <50241F14.2060209@tim.thechases.com> <36EA3847-6713-4C12-B47B-9B5E10325F00@gmail.com> <502429C3.5000600@tim.thechases.com> <mailman.3120.1344548050.4697.python-list@python.org> <MsWUr.1183213$%k.489563@fx20.am4> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.3129.1344551238.4697.python-list@python.org> (permalink) |
On 08/09/2012 06:03 PM, Andrew Cooper wrote:
> On 09/08/2012 22:34, Roman Vashkevich wrote:
>> Actually, they are different.
>> Put a dict.{iter}items() in an O(k^N) algorithm and make it a hundred thousand entries, and you will feel the difference.
>> Dict uses hashing to get a value from the dict and this is why it's O(1).
>>
> Sligtly off topic, but looking up a value in a dictionary is actually
> O(n) for all other entries in the dict which suffer a hash collision
> with the searched entry.
>
> True, a sensible choice of hash function will reduce n to 1 in common
> cases, but it becomes an important consideration for larger datasets.
>
> ~Andrew
I'm glad you're wrong for CPython's dictionaries. The only time the
lookup would degenerate to O[n] would be if the hash table had only one
slot. CPython sensibly increases the hash table size when it becomes
too small for efficiency.
Where have you seen dictionaries so poorly implemented?
--
DaveA
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save dictionary to a file without brackets. giuseppe.amatulli@gmail.com - 2012-08-09 13:11 -0700
Re: save dictionary to a file without brackets. Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 00:22 +0400
Re: save dictionary to a file without brackets. Tim Chase <python.list@tim.thechases.com> - 2012-08-09 15:35 -0500
Re: save dictionary to a file without brackets. Giuseppe Amatulli <giuseppe.amatulli@gmail.com> - 2012-08-09 15:35 -0500
Re: save dictionary to a file without brackets. Gelonida N <gelonida@gmail.com> - 2012-08-09 22:35 +0200
Re: save dictionary to a file without brackets. Giuseppe Amatulli <giuseppe.amatulli@gmail.com> - 2012-08-09 15:38 -0500
Re: save dictionary to a file without brackets. Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 00:41 +0400
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-09 22:17 +0100
Re: save dictionary to a file without brackets. Tim Chase <python.list@tim.thechases.com> - 2012-08-09 16:21 -0500
Re: save dictionary to a file without brackets. Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 01:34 +0400
Re: save dictionary to a file without brackets. Andrew Cooper <amc96@cam.ac.uk> - 2012-08-09 23:03 +0100
Re: save dictionary to a file without brackets. Dave Angel <d@davea.name> - 2012-08-09 18:26 -0400
Re: save dictionary to a file without brackets. Andrew Cooper <amc96@cam.ac.uk> - 2012-08-09 23:54 +0100
Re: save dictionary to a file without brackets. Roy Smith <roy@panix.com> - 2012-08-09 19:05 -0400
Re: save dictionary to a file without brackets. Chris Angelico <rosuav@gmail.com> - 2012-08-10 09:14 +1000
Re: save dictionary to a file without brackets. Roy Smith <roy@panix.com> - 2012-08-09 19:24 -0400
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-10 00:33 +0100
Re: save dictionary to a file without brackets. Tim Chase <python.list@tim.thechases.com> - 2012-08-09 19:16 -0500
Re: save dictionary to a file without brackets. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-10 08:54 +0000
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-10 10:37 +0100
Re: save dictionary to a file without brackets. Roy Smith <roy@panix.com> - 2012-08-10 08:29 -0400
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-10 15:47 +0100
Re: save dictionary to a file without brackets. alex23 <wuwei23@gmail.com> - 2012-08-12 17:15 -0700
Re: save dictionary to a file without brackets. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-13 08:05 +0000
Re: save dictionary to a file without brackets. alex23 <wuwei23@gmail.com> - 2012-08-13 09:16 -0700
Re: save dictionary to a file without brackets. rusi <rustompmody@gmail.com> - 2012-08-13 08:55 -0700
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-13 13:37 +0100
Re: save dictionary to a file without brackets. alex23 <wuwei23@gmail.com> - 2012-08-13 09:14 -0700
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-13 18:07 +0100
Re: save dictionary to a file without brackets. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-14 02:54 +0000
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-14 12:33 +0100
Re: save dictionary to a file without brackets. Alister <alister.ware@ntlworld.com> - 2012-08-14 15:05 +0000
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-14 19:15 +0100
Re: save dictionary to a file without brackets. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-13 18:43 +0100
Re: save dictionary to a file without brackets. alex23 <wuwei23@gmail.com> - 2012-08-13 18:32 -0700
Re: save dictionary to a file without brackets. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-10 12:34 -0400
Re: save dictionary to a file without brackets. Dave Angel <d@davea.name> - 2012-08-09 20:27 -0400
Re: save dictionary to a file without brackets. Chris Angelico <rosuav@gmail.com> - 2012-08-10 10:31 +1000
Re: save dictionary to a file without brackets. Dave Angel <d@davea.name> - 2012-08-09 19:38 -0400
Re: save dictionary to a file without brackets. Tim Chase <python.list@tim.thechases.com> - 2012-08-09 17:39 -0500
Re: save dictionary to a file without brackets. Chris Kaynor <ckaynor@zindagigames.com> - 2012-08-09 15:37 -0700
Re: save dictionary to a file without brackets. Chris Angelico <rosuav@gmail.com> - 2012-08-10 08:53 +1000
Re: save dictionary to a file without brackets. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-11 11:26 +0000
Re: save dictionary to a file without brackets. 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-12 04:59 -0700
Re: save dictionary to a file without brackets. Chris Angelico <rosuav@gmail.com> - 2012-08-10 09:01 +1000
Re: save dictionary to a file without brackets. Dave Angel <d@davea.name> - 2012-08-09 19:42 -0400
Re: save dictionary to a file without brackets. 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-09 22:35 -0700
Re: save dictionary to a file without brackets. Terry Reedy <tjreedy@udel.edu> - 2012-08-09 17:46 -0400
Re: save dictionary to a file without brackets. Dave Angel <d@davea.name> - 2012-08-09 17:47 -0400
Re: save dictionary to a file without brackets. 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-10 10:46 -0700
Re: save dictionary to a file without brackets. 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-10 10:46 -0700
Re: save dictionary to a file without brackets. Chris Kaynor <ckaynor@zindagigames.com> - 2012-08-09 14:49 -0700
Re: save dictionary to a file without brackets. Chris Kaynor <ckaynor@zindagigames.com> - 2012-08-09 14:51 -0700
Re: save dictionary to a file without brackets. Giuseppe Amatulli <giuseppe.amatulli@gmail.com> - 2012-08-09 16:53 -0500
Re: save dictionary to a file without brackets. Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 02:02 +0400
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