I have a directed graph and am using PgRouting's driving_distance function. My application needs it (or a related PostreSQL procedure) to return a full set of EDGES emanating out of the source, and not the just the VERTICES.
The Drivetime function (the essential "Dijkstra algorithm") returns the following columns:
CostToSource (from that vertex)
Edge_id (where edge.source = vertex_id )
Of course a vertex can have several edges associated with it and only one edge per vertex is returned in this table (for some reason).
Qu: Can anybody think of a way to relate the above information with the network so that I can get what I need, which is:
Related Pair ( Vertex_ID, Edge_ID)
CostToSource (From vertex_id)
Hint: the obvious problem with joining vertex_id to the "source" in the network table is that some of the links do not belong in the result set. Any link heading back to the source should be excluded.