Class DijkstraClosestFirstIterator<V,E>

java.lang.Object
org.jgrapht.alg.shortestpath.DijkstraClosestFirstIterator<V,E>
Type Parameters:
V - the graph vertex type
E - the graph edge type
All Implemented Interfaces:
Iterator<V>

class DijkstraClosestFirstIterator<V,E> extends Object implements Iterator<V>
A light-weight version of the closest-first iterator for a directed or undirected graphs. For this iterator to work correctly the graph must not be modified during iteration. Currently there are no means to ensure that, nor to fail-fast. The results of such modifications are undefined.

The metric for closest here is the weighted path length from a start vertex, i.e. Graph.getEdgeWeight(Edge) is summed to calculate path length. Negative edge weights will result in an IllegalArgumentException. Optionally, path length may be bounded by a finite radius. This iterator can use a custom heap implementation.

NOTE: This is an internal iterator for use in shortest paths algorithms. For an iterator that is suitable to return to the users see ClosestFirstIterator. This implementation is faster since it does not support graph traversal listeners nor disconnected components.

  • Field Details

    • graph

      private final Graph<V,E> graph
    • source

      private final V source
    • radius

      private final double radius
    • seen

      private final Map<V,org.jheaps.AddressableHeap.Handle<Double,Pair<V,E>>> seen
    • heap

      private org.jheaps.AddressableHeap<Double,Pair<V,E>> heap
  • Constructor Details

    • DijkstraClosestFirstIterator

      public DijkstraClosestFirstIterator(Graph<V,E> graph, V source)
      Creates a new iterator for the specified graph. Iteration will start at the specified start vertex and will be limited to the connected component that includes that vertex. This iterator will use pairing heap as a default heap implementation.
      Parameters:
      graph - the graph to be iterated.
      source - the source vertex
    • DijkstraClosestFirstIterator

      public DijkstraClosestFirstIterator(Graph<V,E> graph, V source, double radius)
      Creates a new radius-bounded iterator for the specified graph. Iteration will start at the specified start vertex and will be limited to the subset of the connected component which includes that vertex and is reachable via paths of weighted length less than or equal to the specified radius. This iterator will use pairing heap as a default heap implementation.
      Parameters:
      graph - the graph
      source - the source vertex
      radius - limit on weighted path length, or Double.POSITIVE_INFINITY for unbounded search
    • DijkstraClosestFirstIterator

      public DijkstraClosestFirstIterator(Graph<V,E> graph, V source, Supplier<org.jheaps.AddressableHeap<Double,Pair<V,E>>> heapSupplier)
      Creates a new iterator for the specified graph. Iteration will start at the specified start vertex and will be limited to the connected component that includes that vertex. This iterator will use heap supplied by the heapSupplier
      Parameters:
      graph - the graph to be iterated.
      source - the source vertex
      heapSupplier - supplier of the preferable heap implementation
    • DijkstraClosestFirstIterator

      public DijkstraClosestFirstIterator(Graph<V,E> graph, V source, double radius, Supplier<org.jheaps.AddressableHeap<Double,Pair<V,E>>> heapSupplier)
      Creates a new radius-bounded iterator for the specified graph. Iteration will start at the specified start vertex and will be limited to the subset of the connected component which includes that vertex and is reachable via paths of weighted length less than or equal to the specified radius. This iterator will use the heap supplied by heapSupplier
      Parameters:
      graph - the graph
      source - the source vertex
      radius - limit on weighted path length, or Double.POSITIVE_INFINITY for unbounded search
      heapSupplier - supplier of the preferable heap implementation
  • Method Details

    • hasNext

      public boolean hasNext()
      Specified by:
      hasNext in interface Iterator<V>
    • next

      public V next()
      Specified by:
      next in interface Iterator<V>
    • getPaths

      Return the paths computed by this iterator. Only the paths to vertices which are already returned by the iterator will be shortest paths. Additional paths to vertices which are not yet returned (settled) by the iterator might be included with the following properties: the distance will be an upper bound on the actual shortest path and the distance will be inside the radius of the search.
      Returns:
      the single source paths
    • getDistanceAndPredecessorMap

      public Map<V,Pair<Double,E>> getDistanceAndPredecessorMap()
      Return all paths using the traditional representation of the shortest path tree, which stores for each vertex (a) the distance of the path from the source vertex and (b) the last edge used to reach the vertex from the source vertex.

      Only the paths to vertices which are already returned by the iterator will be shortest paths. Additional paths to vertices which are not yet returned (settled) by the iterator might be included with the following properties: the distance will be an upper bound on the actual shortest path and the distance will be inside the radius of the search.

      Returns:
      a distance and predecessor map
    • updateDistance

      private void updateDistance(V v, E e, double distance)