Bidirectional Dijkstra - Family of functions¶
pgr_bdDijkstra - Bidirectional Dijkstra algorithm for the shortest paths.
pgr_bdDijkstraCost - Bidirectional Dijkstra to calculate the cost of the shortest paths
pgr_bdDijkstraCostMatrix - Bidirectional Dijkstra algorithm to create a matrix of costs of the shortest paths.
Synopsis¶
Based on Dijkstra’s algorithm, the bidirectional search finds a shortest path
a starting vertex (start_vid) to an ending vertex (end_vid).
It runs two simultaneous searches: one forward from the source, and one backward from the target,
stopping when the two meet in the middle.
This implementation can be used with a directed graph and an undirected graph.
Characteristics¶
The main Characteristics are:
Process is done only on edges with positive costs.
Values are returned when there is a path.
When the starting vertex and ending vertex are the same, there is no path.
The agg_cost the non included values (v, v) is 0
When the starting vertex and ending vertex are the different and there is no path:
The agg_cost the non included values (u, v) is \(\infty\)
Running time (worse case scenario): \(O((V \log V + E))\)
For large graphs where there is a path bewtween the starting vertex and ending vertex:
It is expected to terminate faster than pgr_dijkstra
See Also¶
Indices and tables