def test_collapse_degree_2_vtxs():
g = igraph.Graph(directed=True)
# a square with a diagonal + tail
g.add_vertices(5)
# the square
g.add_edges([
(0, 1),
(1, 2),
(2, 3),
(3, 0),
])
# the diagonal
g.add_edges([(0, 2)])
# the tail
g.add_edges([(1, 4)])
g.es["weight"] = range(6)
# so now vertex 3 is just a thru-node
eq_(len(g.vs), 5)
eq_(len(g.es), 6)
eq_(len(g.vs.select(_degree_eq=1)), 1)
eq_(len(g.vs.select(_degree_eq=2)), 1)
eq_(len(g.vs.select(_degree_eq=3)), 3)
ret = gt.collapse_degree_2_vtxs(g)
eq_(ret, 1)
# Now it is clean
eq_(len(g.vs), 4)
eq_(len(g.es), 5)
eq_(len(g.vs.select(_degree_eq=1)), 1)
eq_(len(g.vs.select(_degree_eq=2)), 0)
eq_(len(g.vs.select(_degree_eq=3)), 3)
def test_collapse_degree_2_vtxs_bollard():
# We should not remove nodes are source/sink only.
g = igraph.Graph(directed=True)
# two boxes
g.add_vertices(6)
# the outer rectange
g.add_edges([
(1, 0),
(0, 5),
(2, 1),
(2, 3),
(3, 4),
(4, 5),
])
# the center line
g.add_edges([(4, 1)])
eq_(g.vs[0].indegree(), 1)
eq_(g.vs[0].outdegree(), 1)
eq_(g.vs[5].indegree(), 2)
eq_(g.vs[5].outdegree(), 0)
eq_(g.vs[1].indegree(), 2)
eq_(g.vs[1].outdegree(), 1)
eq_(g.vs[2].indegree(), 0)
eq_(g.vs[2].outdegree(), 2)
eq_(g.vs[3].indegree(), 1)
eq_(g.vs[3].outdegree(), 1)
eq_(g.vs[4].indegree(), 1)
eq_(g.vs[4].outdegree(), 2)
# so now vertex 0 and 3 are thru-ways
# vertex 5 and 2 are bollards
eq_(len(g.vs), 6)
eq_(len(g.es), 7)
g.es["weight"] = range(7)
assert(gt.is_bollard(g.vs[2]))
assert(gt.is_bollard(g.vs[5]))
assert(not gt.is_bollard(g.vs[1]))
assert(not gt.is_bollard(g.vs[3]))
ret = gt.collapse_degree_2_vtxs(g)
# deleted 4
eq_(ret, 2)
# Now it is clean
eq_(len(g.vs), 4)
print [es.tuple for es in g.es]
eq_(len(g.es), 5)
eq_(len(g.vs.select(_degree_eq=2, _indegree_gt=0, _outdegree_gt=0)), 0)
def test_collapse_degree_2_vtxs_bollard():
# We should not remove nodes are source/sink only.
g = igraph.Graph(directed=True)
# two boxes
g.add_vertices(6)
# the outer rectange
g.add_edges([
(1, 0),
(0, 5),
(2, 1),
(2, 3),
(3, 4),
(4, 5),
])
# the center line
g.add_edges([(4, 1)])
eq_(g.vs[0].indegree(), 1)
eq_(g.vs[0].outdegree(), 1)
eq_(g.vs[5].indegree(), 2)
eq_(g.vs[5].outdegree(), 0)
eq_(g.vs[1].indegree(), 2)
eq_(g.vs[1].outdegree(), 1)
eq_(g.vs[2].indegree(), 0)
eq_(g.vs[2].outdegree(), 2)
eq_(g.vs[3].indegree(), 1)
eq_(g.vs[3].outdegree(), 1)
eq_(g.vs[4].indegree(), 1)
eq_(g.vs[4].outdegree(), 2)
# so now vertex 0 and 3 are thru-ways
# vertex 5 and 2 are bollards
eq_(len(g.vs), 6)
eq_(len(g.es), 7)
g.es["weight"] = range(7)
assert(gt.is_bollard(g.vs[2]))
assert(gt.is_bollard(g.vs[5]))
assert(not gt.is_bollard(g.vs[1]))
assert(not gt.is_bollard(g.vs[3]))
ret = gt.collapse_degree_2_vtxs(g)
# deleted 4
eq_(ret, 2)
# Now it is clean
eq_(len(g.vs), 4)
print [es.tuple for es in g.es]
def main(args):
parser = argparse.ArgumentParser()
parser.add_argument('output',
metavar='graph.pickle',
help='Ouput graph file')
parser.add_argument(
'--connection',
default='postgresql://*****:*****@localhost/osrm',
help='Postgres connection string. Default %(default)s')
parser.add_argument('--prune',
action='store_true',
help='Collapse redundant edges, prune tails')
parser.add_argument('--verbose',
action='store_true',
help='Increase logging level')
args = parser.parse_args()
logging.basicConfig(
level=logging.INFO if args.verbose else logging.WARNING)
log.info("Creating DB engine")
engine = create_engine(args.connection, echo=False)
log.info("Creating DB session")
Session = sessionmaker(bind=engine)
session = Session()
g = build_graph(session)
if args.prune:
log.info("Collapsing unidirectional strings")
pruned = graphtools.collapse_degree_2_vtxs(g)
log.info("Removed %i thru-nodes", pruned)
log.info("Collapsing bidirectional strings")
pruned = graphtools.collapse_bidirectional_streets(g)
log.info("Removed %i thru-nodes", pruned)
log.info("Snipping tails")
snipped = graphtools.delete_degree_1_vtxs(g)
log.info("Removed %i tails", snipped)
loners = graphtools.delete_degree_0_vtxs(g)
log.info("Removed %i loner-nodes (should be zero)", loners)
redundancies = graphtools.identify_rendudant_nodes(g)
log.info("Marked %i nodes as redundant", redundancies)
log.info("Saving graph to %s", args.output)
g.save(args.output)
def test_collapse_degree_2_vtxs_complex():
g = igraph.Graph(directed=True)
# two boxes
g.add_vertices(6)
# the outer rectange
g.add_edges([
(0, 1),
(1, 2),
(2, 3),
(3, 4),
(4, 5),
(5, 0),
])
# the center line
g.add_edges([(1, 4)])
# This makes it so all collapsed edges
# have conserved flow.
g.es["weight"] = [
3,
4,
4,
4,
3,
3,
2
]
eq_(g.es[g.get_eid(1, 4)]["weight"], 2)
eq_(g.es[g.get_eid(0, 1)]["weight"], 3)
eq_(g.es[g.get_eid(1, 2)]["weight"], 4)
# so now vertex 5-0 and 2-3 are thru-ways
eq_(len(g.vs), 6)
eq_(len(g.es), 7)
ret = gt.collapse_degree_2_vtxs(g)
# deleted 4
eq_(ret, 4)
# Now it is clean
eq_(len(g.vs), 2)
eq_(len(g.es), 3)
eq_(len(g.vs.select(_degree_eq=2)), 0)
# Edge weights should be respected
eq_(g.es["weight"], [2, 3, 4])
def main(args):
parser = argparse.ArgumentParser()
parser.add_argument('output', metavar='graph.pickle',
help='Ouput graph file')
parser.add_argument(
'--connection',
default='postgresql://*****:*****@localhost/osrm',
help='Postgres connection string. Default %(default)s'
)
parser.add_argument('--prune', action='store_true',
help='Collapse redundant edges, prune tails')
parser.add_argument('--verbose', action='store_true',
help='Increase logging level')
args = parser.parse_args()
logging.basicConfig(
level=logging.INFO if args.verbose else logging.WARNING)
log.info("Creating DB engine")
engine = create_engine(args.connection, echo=False)
log.info("Creating DB session")
Session = sessionmaker(bind=engine)
session = Session()
g = build_graph(session)
if args.prune:
log.info("Collapsing unidirectional strings")
pruned = graphtools.collapse_degree_2_vtxs(g)
log.info("Removed %i thru-nodes", pruned)
log.info("Collapsing bidirectional strings")
pruned = graphtools.collapse_bidirectional_streets(g)
log.info("Removed %i thru-nodes", pruned)
log.info("Snipping tails")
snipped = graphtools.delete_degree_1_vtxs(g)
log.info("Removed %i tails", snipped)
loners = graphtools.delete_degree_0_vtxs(g)
log.info("Removed %i loner-nodes (should be zero)", loners)
redundancies = graphtools.identify_rendudant_nodes(g)
log.info("Marked %i nodes as redundant", redundancies)
log.info("Saving graph to %s", args.output)
g.save(args.output)