def FindDisjunctGraphs (dbname):
db = OSMDB(dbname)
#should really be done before simplifying and splitting
#fuse_nodes(db)
c = db.cursor()
c.execute("DROP table if exists graph_nodes")
c.execute("DROP table if exists graph_edges")
c.execute("CREATE table graph_nodes (graph_num INTEGER, node_id TEXT, WKT_GEOMETRY TEXT)")
c.execute("CREATE table graph_edges (graph_num INTEGER, edge_id TEXT, WKT_GEOMETRY TEXT)")
c.execute("CREATE index graph_nodes_id_indx ON graph_nodes(node_id)")
c.execute("CREATE index graph_edges_id_indx ON graph_edges(edge_id)")
c.close()
g = Graph()
t0 = time.time()
vertices = {}
print "load vertices into memory"
for row in db.execute("SELECT DISTINCT start_nd from edges"):
g.add_vertex(str(row[0]))
vertices[str(row[0])] = 0
#print str(row[0])
for row in db.execute("SELECT DISTINCT end_nd from edges"):
g.add_vertex(str(row[0]))
vertices[str(row[0])] = 0
#k = vertices.keys()
#k.sort()
#print k, len(k)
print "load edges into memory"
for start_nd, end_nd in db.execute("SELECT start_nd, end_nd from edges"):
g.add_edge(start_nd, end_nd, Link())
g.add_edge(end_nd, start_nd, Link())
#print start_nd, end_nd
db.conn.commit()
t1 = time.time()
print "populating graph took: %f"%(t1-t0)
t0 = t1
print len(vertices)
iteration = 1
c = db.cursor()
while True:
#c.execute("SELECT id from nodes where id not in (SELECT node_id from graph_nodes) LIMIT 1")
try:
vertex, dummy = vertices.popitem()
#print vertex
except:
break
spt = g.shortest_path_tree(vertex, None, State(1,0))
print spt.size
for v in spt.vertices:
lat, lon = c.execute("SELECT lat, lon from nodes where id=?", (v.label, )).next()
c.execute("INSERT into graph_nodes VALUES (?, ?, ?)", (iteration, v.label, "POINT(%f %f)" % (lon, lat)))
for e in v.outgoing: # this gives a wierd maze graph, should do for all edges outside loop.
lat1, lon1 = c.execute("SELECT lat, lon from nodes where id=?", (e.from_v.label, )).next()
lat2, lon2 = c.execute("SELECT lat, lon from nodes where id=?", (e.to_v.label, )).next()
c.execute("INSERT into graph_edges VALUES (?, ?, ?)",
(iteration, e.from_v.label + '->' + e.to_v.label, "LINESTRING(%f %f, %f %f)" % (lon1, lat1, lon2, lat2)))
#print v.label
vertices.pop(v.label, None)
g.remove_vertex(v.label, True, True)
#print v.label
spt.destroy()
t1 = time.time()
print "pass %s took: %f nvertices %d"%(iteration, t1-t0, len(vertices))
t0 = t1
iteration += 1
c.close()
db.conn.commit()
g.destroy()
# audit
for gnum, count in db.execute("SELECT graph_num, count(*) FROM graph_nodes GROUP BY graph_num"):
print "FOUND: %s=%s" % (gnum, count)
