#6484: sage.combinat.ranker improvements
-------------------------------------+-------------------------------------
Reporter: nthiery | Owner: nthiery
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: rank, unrank | Merged in:
Authors: nthiery | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/nthiery/sage_combinat_ranker_improvements|
32d5cea664e153895d663b5913e45d03b8c0a305
Dependencies: | Stopgaps:
-------------------------------------+-------------------------------------
Changes (by nthiery):
* status: new => needs_review
* commit: => 32d5cea664e153895d663b5913e45d03b8c0a305
* upstream: => N/A
Old description:
> sage.combinat.ranker needs improvements:
> - With:
> {{{
> sage: f = sage.combinat.ranker.rank_from_list([...])
> }}}
>
> f uses list.index, and is therefore O(n). This should be made O(1)
> with a hash table.
>
> - The rank / unrank objects produced by this library should be
> picklable.
>
> - ...?
>
> patch under construction on the sage-combinat patch server.
New description:
sage.combinat.ranker needs improvements:
- With:
{{{
sage: f = sage.combinat.ranker.rank_from_list([...])
}}}
f uses ``list.index``, and is therefore `O(n)`. This should be made
`O(1)` with a hash table.
Further potential improvement (for a later ticket?):
- make the rank / unrank objects produced by this library picklable.
--
Comment:
New commits:
||[http://git.sagemath.org/sage.git/commit/?id=32d5cea664e153895d663b5913e45d03b8c0a305
32d5cea]||{{{6484: implementation of sage.combinat.ranker.rank_from_list
to be constant time}}}||
--
Ticket URL: <http://trac.sagemath.org/ticket/6484#comment:6>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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