template <class Graph, class DistanceMatrix, class P, class T, class R> bool johnson_all_pairs_shortest_paths(Graph& g, DistanceMatrix& D, const bgl_named_params<P, T, R>& params = all defaults)
This algorithm finds the shortest distance between every pair of vertices in the graph. The algorithm returns false if there is a negative weight cycle in the graph and true otherwise. The distance between each pair of vertices is stored in the distance matrix D. This is one of the more time intensive graph algorithms, having a time complexity of O(V E log V).
boost/graph/johnson_all_pairs_shortest.hpp
A directed or undirected graph. The graph type must be a model of Vertex List Graph, Edge List Graph, and Incidence Graph.OUT: DistanceMatrix& D
The length of the shortest path between each pair of vertices u,v in the graph is stored in D[u][v].
The weight or ``length'' of each edge in the graph. The type WeightMap must be a model of Readable Property Map. The edge descriptor type of the graph needs to be usable as the key type for the weight map. The value type for the map must be Addable with the value type of the distance map.UTIL: weight_map2(WeightMap2 w2_map)
Default: get(edge_weight, g)
The algorithm requires storage for modified edge weights. The type WeightMap2 must be a model of Read/Write Property Map. The edge descriptor type of the graph needs to be usable as the key type for the weight map. The value type for the map must be Addable with the value type of the distance map.IN: vertex_index_map(VertexIndexMap i_map)
Default: get(edge_weight2, g)
This maps each vertex to an integer in the range [0, num_vertices(g)). This is necessary for efficient updates of the heap data structure in the internal call to Dijkstra's algorithm. The type VertexIndexMap must be a model of Readable Property Map. The value type of the map must be an integer type. The vertex descriptor type of the graph needs to be usable as the key type of the map.UTIL/OUT: distance_map(DistanceMap d_map)
Default: get(vertex_index, g)
The shortest path weight from the source vertex s to each vertex in the graph g is recorded in this property map. The shortest path weight is the sum of the edge weights along the shortest path. The type DistanceMap must be a model of \concept{ReadWritePropertyMap}. The vertex descriptor type of the graph needs to be usable as the key type of the distance map. The value type of the distance map must be Less Than Comparable.IN: distance_compare(CompareFunction cmp)
Default: iterator_property_map created from a std::vector of the WeightMap's value type of size num_vertices(g) and using the i_map for the index map.
This function is use to compare distances to determine which vertex is closer to the source vertex. The CompareFunction type must be a model of \stlconcept{BinaryPredicate} and have argument types that match the value type of the DistanceMap property map.IN: distance_combine(CombineFunction cmb)
Default: std::less<D> with D=typename property_traits<DistanceMap>::value_type
This function is used to combine distances to compute the distance of a path. The CombineFunction type must be a model of Binary Function. The first argument type of the binary function must match the value type of the DistanceMap property map and the second argument type must match the value type of the WeightMap property map. The result type must be the same type as the distance value type.IN: distance_inf(InfinityGenerator inf)
Default: std::plus<D> with D=typename property_traits<DistanceMap>::value_type
This function is used to initialize the distance for each vertex before the start of the algorithm. The InfinityGenerator type must model the Generator concept. The result type of the generator must be convertible to the value type of the DistanceMap. The default infinity generator uses std::numeric_limits::max().IN: distance_zero(ZeroGenerator zero)
Default: detail::generate_infinity<D> with D=typename property_traits<DistanceMap>::value_type
This function is used to initialize the distance for the source vertex before the start of the algorithm. The ZeroGenerator type must model the Generatorconcept. The result type of the generator must be convertible to the value type of the DistanceMap.UTIL/OUT: color_map(ColorMap c_map)
Default: detail::generate_zero<D> with D=typename property_traits<DistanceMap>::value_type
This is used during the execution of the algorithm to mark the vertices. The vertices start out white and become gray when they are inserted in the queue. They then turn black when they are removed from the queue. At the end of the algorithm, vertices reachable from the source vertex will have been colored black. All other vertices will still be white. The type ColorMap must be a model of Read/Write Property Map. A vertex descriptor must be usable as the key type of the map, and the value type of the map must be a model of Color Value.
Default: an iterator_property_map created from a std::vector of default_color_type of size num_vertices(g) and using the i_map for the index map.
The file example/johnson.cpp applies
Johnson's algorithm for all-pairs shortest paths to the example graph
from page 568 of the CLR [8].
Copyright © 2000 | Jeremy Siek, Univ.of Notre Dame (jsiek@lsc.nd.edu) |