Module org.jgrapht.core
Package org.jgrapht.alg.shortestpath

Class IntVertexDijkstraShortestPath<E>

java.lang.Object
org.jgrapht.alg.shortestpath.IntVertexDijkstraShortestPath<E>
Type Parameters:
E - the graph edge type
All Implemented Interfaces:
ShortestPathAlgorithm<Integer,E>
public final class IntVertexDijkstraShortestPath<E> extends Object
Dijkstra Shortest Path implementation specialized for graphs with integer vertices.

This class avoids using hash tables when the vertices are numbered from $0$ to $n-1$ where $n$ is the number of vertices of the graph. If vertices are not in this range, then they are mapped in this range using an open addressing hash table (linear probing).

This implementation should be faster than our more generic one which is DijkstraShortestPath since it avoids the extensive use of hash tables.

By default a 4-ary heap is used. The user is free to use a custom heap implementation during construction time. Regarding the choice of heap, it is generally known that it depends on the particular workload. For more details and experiments which can help someone make the choice, read the following paper: Larkin, Daniel H., Siddhartha Sen, and Robert E. Tarjan. "A back-to-basics empirical study of priority queues." 2014 Proceedings of the Sixteenth Workshop on Algorithm Engineering and Experiments (ALENEX). Society for Industrial and Applied Mathematics, 2014.

Author:
Dimitrios Michail

  • Field Details

    • 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:

    • 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:

    • 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:

    • graph

      protected final Graph<Integer,E> graph
      The underlying graph.

  • Constructor Details

    • IntVertexDijkstraShortestPath

      public IntVertexDijkstraShortestPath(Graph<Integer,E> graph)
      Constructs a new instance of the algorithm for a given graph.
      Parameters:
      graph - the graph

    • IntVertexDijkstraShortestPath

      public IntVertexDijkstraShortestPath(Graph<Integer,E> graph, Supplier<org.jheaps.AddressableHeap<Double,Integer>> heapSupplier)
      Constructs a new instance of the algorithm for a given graph.
      Parameters:
      graph - the graph
      heapSupplier - supplier of the preferable heap implementation

  • Method Details

    • findPathBetween

      public static <E> GraphPath<Integer,E> findPathBetween(Graph<Integer,E> graph, Integer source, Integer sink)
      Find a path between two vertices. For a more advanced search (e.g. using another heap), use the constructor instead.
      Type Parameters:
      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<Integer,E> getPath(Integer source, Integer 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

    • getPaths

      public ShortestPathAlgorithm.SingleSourcePaths<Integer,E> getPaths(Integer source)
      Compute all shortest paths starting from a single source vertex.

      Note that in the case of Dijkstra's algorithm it is more efficient to compute all single-source shortest paths using this method than repeatedly invoking getPath(Integer, Integer) for the same source but different sink vertex.

      Specified by:
      getPaths in interface ShortestPathAlgorithm<Integer,E>
      Parameters:
      source - the source vertex
      Returns:
      the shortest paths

    • getPathWeight

      public double getPathWeight(Integer source, Integer 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<Integer,E> createEmptyPath(Integer source, Integer 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