Package org.jgrapht.alg.shortestpath

Class BidirectionalDijkstraShortestPath<V,​E>

  • Type Parameters:
    V - the graph vertex type
    E - the graph edge type
    All Implemented Interfaces:
    ShortestPathAlgorithm<V,​E>
    public final class BidirectionalDijkstraShortestPath<V,​E>
extends BaseBidirectionalShortestPathAlgorithm<V,​E>
    A bidirectional version of Dijkstra's algorithm.

    See the Wikipedia article for details and references about bidirectional search. This technique does not change the worst-case behavior of the algorithm but reduces, in some cases, the number of visited vertices in practice. This implementation alternatively constructs forward and reverse paths from the source and target vertices respectively.

    This iterator can use a custom heap implementation, which can specified during the construction time. Pairing heap is used by default

    Author:
    Dimitrios Michail
    See Also:
    DijkstraShortestPath

    • Field Detail

      • GRAPH_CONTAINS_A_NEGATIVE_WEIGHT_CYCLE

        protected static final String GRAPH_CONTAINS_A_NEGATIVE_WEIGHT_CYCLE
        Error message for reporting the existence of a negative-weight cycle.
        See Also:
        Constant Field Values

      • GRAPH_MUST_CONTAIN_THE_SOURCE_VERTEX

        protected static final String GRAPH_MUST_CONTAIN_THE_SOURCE_VERTEX
        Error message for reporting that a source vertex is missing.
        See Also:
        Constant Field Values

      • GRAPH_MUST_CONTAIN_THE_SINK_VERTEX

        protected static final String GRAPH_MUST_CONTAIN_THE_SINK_VERTEX
        Error message for reporting that a sink vertex is missing.
        See Also:
        Constant Field Values

      • graph

        protected final Graph<V,​E> graph
        The underlying graph.

    • Constructor Detail

      • BidirectionalDijkstraShortestPath

        public BidirectionalDijkstraShortestPath​(Graph<V,​E> graph)
        Constructs a new instance for a specified graph.
        Parameters:
        graph - the input graph

      • BidirectionalDijkstraShortestPath

        public BidirectionalDijkstraShortestPath​(Graph<V,​E> graph,
                                         Supplier<org.jheaps.AddressableHeap<Double,​Pair<V,​E>>> heapSupplier)
        Constructs a new instance for a specified graph. The constructed algorithm will use the heap supplied by the heapSupplier.
        Parameters:
        graph - the input graph
        heapSupplier - supplier of the preferable heap implementation

      • BidirectionalDijkstraShortestPath

        public BidirectionalDijkstraShortestPath​(Graph<V,​E> graph,
                                         double radius)
        Constructs a new instance for a specified graph.
        Parameters:
        graph - the input graph
        radius - limit on path length, or Double.POSITIVE_INFINITY for unbounded search

      • BidirectionalDijkstraShortestPath

        public BidirectionalDijkstraShortestPath​(Graph<V,​E> graph,
                                         double radius,
                                         Supplier<org.jheaps.AddressableHeap<Double,​Pair<V,​E>>> heapSupplier)
        Constructs a new instance for a specified graph. The constructed algorithm will use the heap supplied by the heapSupplier.
        Parameters:
        graph - the input graph
        radius - limit on path length, or Double.POSITIVE_INFINITY for unbounded search
        heapSupplier - supplier of the preferable heap implementation

    • Method Detail

      • findPathBetween

        public static <V,​E> GraphPath<V,​E> findPathBetween​(Graph<V,​E> graph,
                                                               V source,
                                                               V sink)
        Find a path between two vertices. For a more advanced search (e.g. limited by radius), use the constructor instead.
        Type Parameters:
        V - the graph vertex type
        E - the graph edge type
        Parameters:
        graph - the graph to be searched
        source - the vertex at which the path should start
        sink - the vertex at which the path should end
        Returns:
        a shortest path, or null if no path exists

      • getPath

        public GraphPath<V,​E> getPath​(V source,
                                    V sink)
        Description copied from interface: ShortestPathAlgorithm
        Get a shortest path from a source vertex to a sink vertex.
        Parameters:
        source - the source vertex
        sink - the target vertex
        Returns:
        a shortest path or null if no path exists

      • getPathWeight

        public double getPathWeight​(V source,
                            V sink)
        Get the weight of the shortest path from a source vertex to a sink vertex. Returns Double.POSITIVE_INFINITY if no path exists.
        Specified by:
        getPathWeight in interface ShortestPathAlgorithm<V,​E>
        Parameters:
        source - the source vertex
        sink - the sink vertex
        Returns:
        the weight of the shortest path from a source vertex to a sink vertex, or Double.POSITIVE_INFINITY if no path exists

      • createEmptyPath

        protected final GraphPath<V,​E> createEmptyPath​(V source,
                                                     V sink)
        Create an empty path. Returns null if the source vertex is different than the target vertex.
        Parameters:
        source - the source vertex
        sink - the sink vertex
        Returns:
        an empty path or null null if the source vertex is different than the target vertex