Bidirectional Dijkstra - Family of functions - pgRouting Manual (3.4)

Synopsis

Based on Dijkstra’s algorithm, the bidirectional search finds a shortest path a starting vertex to an ending vertex.

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.

  • A negative value on a cost column is interpreted as the edge does not exist.

• Values are returned when there is a path.

• When there is no path:

  • When the starting vertex and ending vertex are the same.

    • The aggregate cost of the non included values \((v, v)\) is \(0\)

  • When the starting vertex and ending vertex are the different and there is no path:

    • The aggregate cost the non included values \((u, v)\) is \(\infty\)

• For optimization purposes, any duplicated value in the starting vertices or on the ending vertices are ignored.

• 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

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