#7540: Speed up shortest_path_all_pairs() and update distance_graph
----------------------------+-----------------------------------------------
Reporter: ncohen | Owner: rlm
Type: enhancement | Status: new
Priority: major | Milestone: sage-4.3
Component: graph theory | Keywords:
Work_issues: | Author:
Upstream: N/A | Reviewer:
Merged: |
----------------------------+-----------------------------------------------
Description changed by ncohen:
Old description:
> As mentionned in #7533 by Rob Beezer, the function
> shortest_path_all_pairs() is much slower than computing independently all
> the distances, which is a bit worrying. Easy explanation ( at least it is
> an explanation for me, though there may be a deeper one ), distance() is
> a function from NetworkX while the Floyd-Marshall algorithm is directly
> written in Python, hence the slowness.
>
> This function is very fundamental and should be improved ! The difference
> is amazing :
>
> {{{
> sage: g=graphs.RandomGNP(200,.1)
> sage: time e=g.shortest_path_all_pairs()
> CPU times: user 16.51 s, sys: 0.06 s, total: 16.57 s
> Wall time: 16.60 s
> sage: time a=[g.distance(i,j) for (i,j) in Subsets(g,2)]
> CPU times: user 1.06 s, sys: 0.00 s, total: 1.06 s
> Wall time: 1.06 s
> }}}
New description:
As mentionned in #7533 by Rob Beezer, the function
shortest_path_all_pairs() is much slower than computing independently all
the distances, which is a bit worrying. Easy explanation ( at least it is
an explanation for me, though there may be a deeper one ), distance() is a
function from NetworkX while the Floyd-Marshall algorithm is directly
written in Python, hence the slowness.
This function is very fundamental and should be improved ! The difference
is amazing :
{{{
sage: g=graphs.RandomGNP(200,.1)
sage: time e=g.shortest_path_all_pairs()
CPU times: user 16.51 s, sys: 0.06 s, total: 16.57 s
Wall time: 16.60 s
sage: time a=[g.distance(i,j) for (i,j) in Subsets(g,2)]
CPU times: user 1.06 s, sys: 0.00 s, total: 1.06 s
Wall time: 1.06 s
}}}
See http://groups.google.com/group/sage-
devel/browse_thread/thread/8edd29e9bddc67e5 for discussion.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7540#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
