#14967: Bug with DiGraph
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Reporter: mercatp | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-5.11
Component: graph theory | Resolution:
Keywords: graph | Merged in:
Authors: Paul Mercat | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Dependencies:
Stopgaps: |
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Changes (by rlm):
* cc: ncohen (added)
Comment:
The reason we did this was to make the most common cases as fast as
possible. Since a lot of the graphs in Sage are on the integers [0, 1,
..., n] it is much faster if the underlying representation doesn't have to
spend extra time translating between the user-exposed vertices and those
of the underlying implementation. The reasoning is to take the cheapest
route to integer possible. If the vertex is not an integer, we need to
update translation dictionaries and this is more expensive.
When this code was written Cython would not allow you to assign 1/2 to a C
integer. We used the fact that try blocks are very cheap to take advantage
of this behavior for speed.
I am worried that {{{if u in IntegerRing}}} will take a long time due to
coercion. Have you done any profiling to see the difference?
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Ticket URL: <http://trac.sagemath.org/ticket/14967#comment:1>
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