Avoid comparison of vertex labels in MIP (Step 2)

[dcoudert]

Avoid comparison of vertex labels in graph.py.

CC: @tscrim @fchapoton

Component: graph theory

Author: David Coudert

Branch/Commit: 6acb781

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/26282

[dcoudert]

Commit: 8e3e85c

[dcoudert]

New commits:

8e3e85c

trac #26282: avoid comparison of vertex labels in MIP

[dcoudert]

Branch: public/26282_avoid_comparison_of_vertex_labels

[sagetrac-git]

Changed commit from 8e3e85c to 5221e6a

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

5221e6a

trac #26282: resolve merge conflict with 8.4.beta5

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

2dfc524

trac #26282: use def instead of lambdas

[sagetrac-git]

Changed commit from 5221e6a to 2dfc524

[dcoudert]

comment:4

I change frozenset wrappers from lambda to def. Should I try to do the same for remaining lambda statements like this ?

weight = lambda x: x if x in RR else 1

[tscrim]

comment:6

I think you can get rid of

        def B(e):
            return b[frozenset(e)]

        def R(e):
            return r[frozenset(e)]

        def S(e):
            return frozenset(e)

as they are not simplifying the code (or changing the readability IMO.

I would still use six.iteritems for better memory usage:

-        g_mad = g.subgraph([v for v,l in six.iteritems(p.get_values(d)) if l>m ])
+        d_val = p.get_values(d)
+        g_mad = g.subgraph([v for v,l in d_val.items() if l > m ])

In general, I don't get the point of that change.

More standard convention and faster:

-lists = dict((v, []) for v in self)
+lists = {v: [] for v in self}

sage: %timeit dict((i,-1) for i in range(100))
100000 loops, best of 3: 16.6 µs per loop
sage: %timeit {i:-1 for i in range(100)}
100000 loops, best of 3: 11.7 µs per loop

not fuv in L -> fuv not in L.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

7856e11	trac #: Merged with 8.4.beta7
6acb781	trac #26282: implement reviewer's comments

[sagetrac-git]

Changed commit from 2dfc524 to 6acb781

[dcoudert]

comment:8

I have implemented all your comments.

[tscrim]

comment:9

Thanks. LGTM.

[tscrim]

Reviewer: Travis Scrimshaw

[dcoudert]

comment:10

Thank you !

[vbraun]

Changed branch from public/26282_avoid_comparison_of_vertex_labels to 6acb781