#13599: Bugfix in is_cartesian_product
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Reporter: ncohen | Owner: jason, ncohen, rlm
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.5
Component: graph theory | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers: David Coudert
Authors: Nathann Cohen | Merged in:
Dependencies: | Stopgaps:
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Comment (by ncohen):
Ahahahah. Actually, what I should do is cache the list of edges.. Thanks
for the hint ! `:-)`
{{{
g = graphs.RandomGNP(100,.2)
def test(g):
c = 0
for u,v in g.edge_iterator(labels = False):
for uu,vv in g.edge_iterator(labels = False):
c += uu+vv+u+v
return c
def test2(g):
c = 0
edges = g.edges(labels = False)
for i,(u,v) in enumerate(edges):
for j in range(i+1, len(edges)):
uu,vv = edges[j]
c += uu+vv+u+v
return c
sage: %time test(g)
CPU times: user 4.60 s, sys: 0.00 s, total: 4.60 s
Wall time: 4.60 s
198772752
sage: %time test2(g)
CPU times: user 0.78 s, sys: 0.00 s, total: 0.78 s
Wall time: 0.78 s
99287188
}}}
This thing is ..... very ..... slow `:-/`
Nathann
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13599#comment:3>
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