#11053: improving shortest path all pairs through BFS computations
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Reporter: ncohen | Owner: jason, ncohen, rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.7
Component: graph theory | Keywords:
Author: Nathann Cohen | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Changes (by ncohen):
* status: new => needs_review
Old description:
> After taking a look at the SparseGraph backend, it looks like some time
> is actually spent obtaining the list of neighbors. This patch caches so
> that the out_neighbors method does not have to be called so often.
New description:
After taking a look at the SparseGraph backend, it looks like some time is
actually spent obtaining the list of neighbors. This patch caches so that
the out_neighbors method does not have to be called so often.
Requires : #10905
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Comment:
Before
{{{
sage: g = graphs.Grid2dGraph(60,60)
sage: %time d = g.shortest_path_all_pairs()
CPU times: user 14.52 s, sys: 0.51 s, total: 15.03 s
Wall time: 15.03 s
sage: g = graphs.Grid2dGraph(30,30)
sage: %timeit d = g.shortest_path_all_pairs()
5 loops, best of 3: 752 ms per loop
sage: g = graphs.PetersenGraph()
sage: %timeit d = g.shortest_path_all_pairs()
625 loops, best of 3: 73.5 µs per loop
}}}
After
{{{
sage: g = graphs.Grid2dGraph(60,60)
sage: %time d = g.shortest_path_all_pairs()
CPU times: user 10.70 s, sys: 0.53 s, total: 11.23 s
Wall time: 11.24 s
sage: g = graphs.Grid2dGraph(30,30)
sage: %timeit d = g.shortest_path_all_pairs()
5 loops, best of 3: 549 ms per loop
sage: g = graphs.PetersenGraph()
sage: %timeit d = g.shortest_path_all_pairs()
625 loops, best of 3: 53.4 µs per loop
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11053#comment:1>
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