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212 lines
8.0 KiB
C++
212 lines
8.0 KiB
C++
// (C) Copyright Andrew Sutton 2007
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//
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0 (See accompanying file
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// LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_GRAPH_GEODESIC_DISTANCE_HPP
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#define BOOST_GRAPH_GEODESIC_DISTANCE_HPP
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#include <boost/graph/detail/geodesic.hpp>
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#include <boost/graph/exterior_property.hpp>
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#include <boost/concept/assert.hpp>
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namespace boost
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{
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template <typename Graph,
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typename DistanceType,
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typename ResultType,
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typename Divides = std::divides<ResultType> >
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struct mean_geodesic_measure
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: public geodesic_measure<Graph, DistanceType, ResultType>
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{
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typedef geodesic_measure<Graph, DistanceType, ResultType> base_type;
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typedef typename base_type::distance_type distance_type;
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typedef typename base_type::result_type result_type;
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result_type operator ()(distance_type d, const Graph& g)
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{
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BOOST_CONCEPT_ASSERT(( VertexListGraphConcept<Graph> ));
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BOOST_CONCEPT_ASSERT(( NumericValueConcept<DistanceType> ));
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BOOST_CONCEPT_ASSERT(( NumericValueConcept<ResultType> ));
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BOOST_CONCEPT_ASSERT(( AdaptableBinaryFunctionConcept<Divides,ResultType,ResultType,ResultType> ));
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return (d == base_type::infinite_distance())
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? base_type::infinite_result()
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: div(result_type(d), result_type(num_vertices(g) - 1));
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}
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Divides div;
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};
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template <typename Graph, typename DistanceMap>
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inline mean_geodesic_measure<Graph, typename property_traits<DistanceMap>::value_type, double>
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measure_mean_geodesic(const Graph&, DistanceMap)
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{
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return mean_geodesic_measure<Graph, typename property_traits<DistanceMap>::value_type, double>();
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}
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template <typename T, typename Graph, typename DistanceMap>
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inline mean_geodesic_measure<Graph, typename property_traits<DistanceMap>::value_type, T>
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measure_mean_geodesic(const Graph&, DistanceMap)
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{
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return mean_geodesic_measure<Graph, typename property_traits<DistanceMap>::value_type, T>();
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}
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// This is a little different because it's expected that the result type
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// should (must?) be the same as the distance type. There's a type of
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// transitivity in this thinking... If the average of distances has type
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// X then the average of x's should also be type X. Is there a case where this
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// is not true?
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//
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// This type is a little under-genericized... It needs generic parameters
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// for addition and division.
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template <typename Graph, typename DistanceType>
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struct mean_graph_distance_measure
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: public geodesic_measure<Graph, DistanceType, DistanceType>
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{
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typedef geodesic_measure<Graph, DistanceType, DistanceType> base_type;
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typedef typename base_type::distance_type distance_type;
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typedef typename base_type::result_type result_type;
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inline result_type operator ()(distance_type d, const Graph& g)
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{
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BOOST_CONCEPT_ASSERT(( VertexListGraphConcept<Graph> ));
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BOOST_CONCEPT_ASSERT(( NumericValueConcept<DistanceType> ));
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if(d == base_type::infinite_distance()) {
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return base_type::infinite_result();
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}
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else {
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return d / result_type(num_vertices(g));
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}
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}
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};
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template <typename Graph, typename DistanceMap>
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inline mean_graph_distance_measure<Graph, typename property_traits<DistanceMap>::value_type>
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measure_graph_mean_geodesic(const Graph&, DistanceMap)
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{
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typedef typename property_traits<DistanceMap>::value_type T;
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return mean_graph_distance_measure<Graph, T>();
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}
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template <typename Graph,
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typename DistanceMap,
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typename Measure,
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typename Combinator>
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inline typename Measure::result_type
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mean_geodesic(const Graph& g,
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DistanceMap dist,
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Measure measure,
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Combinator combine)
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{
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BOOST_CONCEPT_ASSERT(( DistanceMeasureConcept<Measure,Graph> ));
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typedef typename Measure::distance_type Distance;
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Distance n = detail::combine_distances(g, dist, combine, Distance(0));
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return measure(n, g);
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}
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template <typename Graph,
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typename DistanceMap,
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typename Measure>
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inline typename Measure::result_type
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mean_geodesic(const Graph& g, DistanceMap dist, Measure measure)
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{
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BOOST_CONCEPT_ASSERT(( DistanceMeasureConcept<Measure,Graph> ));
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typedef typename Measure::distance_type Distance;
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return mean_geodesic(g, dist, measure, std::plus<Distance>());
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}
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template <typename Graph, typename DistanceMap>
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inline double
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mean_geodesic(const Graph& g, DistanceMap dist)
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{ return mean_geodesic(g, dist, measure_mean_geodesic(g, dist)); }
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template <typename T, typename Graph, typename DistanceMap>
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inline T
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mean_geodesic(const Graph& g, DistanceMap dist)
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{ return mean_geodesic(g, dist, measure_mean_geodesic<T>(g, dist)); }
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template <typename Graph,
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typename DistanceMatrixMap,
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typename GeodesicMap,
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typename Measure>
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inline typename property_traits<GeodesicMap>::value_type
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all_mean_geodesics(const Graph& g,
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DistanceMatrixMap dist,
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GeodesicMap geo,
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Measure measure)
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{
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BOOST_CONCEPT_ASSERT(( VertexListGraphConcept<Graph> ));
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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typedef typename graph_traits<Graph>::vertex_iterator VertexIterator;
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BOOST_CONCEPT_ASSERT(( ReadablePropertyMapConcept<DistanceMatrixMap,Vertex> ));
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typedef typename property_traits<DistanceMatrixMap>::value_type DistanceMap;
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BOOST_CONCEPT_ASSERT(( DistanceMeasureConcept<Measure,Graph> ));
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typedef typename Measure::result_type Result;
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BOOST_CONCEPT_ASSERT(( WritablePropertyMapConcept<GeodesicMap,Vertex> ));
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BOOST_CONCEPT_ASSERT(( NumericValueConcept<Result> ));
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// NOTE: We could compute the mean geodesic here by performing additional
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// computations (i.e., adding and dividing). However, I don't really feel
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// like fully genericizing the entire operation yet so I'm not going to.
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Result inf = numeric_values<Result>::infinity();
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Result sum = numeric_values<Result>::zero();
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VertexIterator i, end;
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for(boost::tie(i, end) = vertices(g); i != end; ++i) {
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DistanceMap dm = get(dist, *i);
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Result r = mean_geodesic(g, dm, measure);
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put(geo, *i, r);
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// compute the sum along with geodesics
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if(r == inf) {
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sum = inf;
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}
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else if(sum != inf) {
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sum += r;
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}
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}
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// return the average of averages.
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return sum / Result(num_vertices(g));
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}
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template <typename Graph, typename DistanceMatrixMap, typename GeodesicMap>
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inline typename property_traits<GeodesicMap>::value_type
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all_mean_geodesics(const Graph& g, DistanceMatrixMap dist, GeodesicMap geo)
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{
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BOOST_CONCEPT_ASSERT(( GraphConcept<Graph> ));
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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BOOST_CONCEPT_ASSERT(( ReadablePropertyMapConcept<DistanceMatrixMap,Vertex> ));
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typedef typename property_traits<DistanceMatrixMap>::value_type DistanceMap;
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BOOST_CONCEPT_ASSERT(( WritablePropertyMapConcept<GeodesicMap,Vertex> ));
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typedef typename property_traits<GeodesicMap>::value_type Result;
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return all_mean_geodesics(g, dist, geo, measure_mean_geodesic<Result>(g, DistanceMap()));
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}
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template <typename Graph, typename GeodesicMap, typename Measure>
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inline typename Measure::result_type
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small_world_distance(const Graph& g, GeodesicMap geo, Measure measure)
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{
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BOOST_CONCEPT_ASSERT(( DistanceMeasureConcept<Measure,Graph> ));
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typedef typename Measure::result_type Result;
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Result sum = detail::combine_distances(g, geo, std::plus<Result>(), Result(0));
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return measure(sum, g);
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}
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template <typename Graph, typename GeodesicMap>
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inline typename property_traits<GeodesicMap>::value_type
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small_world_distance(const Graph& g, GeodesicMap geo)
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{ return small_world_distance(g, geo, measure_graph_mean_geodesic(g, geo)); }
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}
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#endif
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