Speedup subposet and _vertex_to_element #11382
Description
A lot of unnecessary and redundant check were performed with a preliminary version of #10998. See a more precise
analyze on
this thread of sage-combinat-devel
sage: P = cutting_poset(WeylGroup(['A',3]))
sage: P.cardinality()
24
Before:
sage: %timeit P.subposet(P.list()[1:])
5 loops, best of 3: 214 ms per loop
After:
sage: %timeit P.subposet(P.list()[1:])
25 loops, best of 3: 24.8 ms per loop
Here is another timing for a bigger poset:
sage: P = cutting_poset(WeylGroup(['A',4]))
sage: P.cardinality()
120
Before:
sage: %timeit P.subposet(P.list()[1:])
5 loops, best of 3: 28.8 s per loop
After:
sage: %timeit P.subposet(P.list()[1:])
5 loops, best of 3: 597 ms per loop
This is basically fixed in the final version of #10998 (run on a
slightly slower machine than for the above timings):
sage: %timeit P.subposet(P.list()[1:])
5 loops, best of 3: 801 ms per loop
The attached patch optimizes it a tiny bit further and adds doctests:
sage: %timeit P.subposet(P.list()[1:])
5 loops, best of 3: 688 ms per loop
Apply: attachment: trac_11382-subposet_to_vertex_speedup-fh.patch
Depends on #10998
CC: @sagetrac-sage-combinat
Component: combinatorics
Keywords: poset, subposet, Cernay2012
Author: Florent Hivert
Reviewer: Nicolas M. Thiéry
Merged: sage-5.0.beta5
Issue created by migration from https://trac.sagemath.org/ticket/11382