template<typename RandomGenerator, typename Graph> class erdos_renyi_iterator { public: typedef std::input_iterator_tag iterator_category; typedef std::pair<vertices_size_type, vertices_size_type> value_type; typedef const value_type& reference; typedef const value_type* pointer; typedef void difference_type; erdos_renyi_iterator(); erdos_renyi_iterator(RandomGenerator& gen, vertices_size_type n, double probability = 0.0, bool allow_self_loops = false); // Iterator operations reference operator*() const; pointer operator->() const; erdos_renyi_iterator& operator++(); erdos_renyi_iterator operator++(int); bool operator==(const erdos_renyi_iterator& other) const; bool operator!=(const erdos_renyi_iterator& other) const; };
This class template implements a generator for Erdöos-Renyi graphs, suitable for initializing an adjacency_list or other graph structure with iterator-based initialization. An Erdöos-Renyi graph G = (n, p) is a graph with n vertices that. The probability of having an edge (u, v) in G is p for any vertices u and v. Typically, there are no self-loops, but the generator can optionally introduce self-loops with probability p.
Erdös-Renyi graphs typically exhibit very little structure. For this reason, they are rarely useful in modeling real-world problems. However, they are often used when determining the theoretical complexity of complex graph algorithms.
erdos_renyi_iterator();
Constructs a past-the-end iterator.
erdos_renyi_iterator(RandomGenerator& gen, vertices_size_type n, double probability = 0.0, bool allow_self_loops = false);
Constructs an Erdös-Renyi generator iterator that creates a graph with n vertices and edges with probability probability. Probabilities are drawn from the random number generator gen. Self-loops are permitted only when allow_self_loops is true.
#include <boost/graph/adjacency_list.hpp> #include <boost/graph/erdos_renyi_generator.hpp> #include <boost/random/linear_congruential.hpp> typedef boost::adjacency_list<> Graph; typedef boost::erdos_renyi_iterator<boost::minstd_rand, Graph> ERGen; int main() { boost::minstd_rand gen; // Create graph with 100 nodes and edges with probability 0.05 Graph g(ERGen(gen, 100, 0.05), ERGen(), 100); return 0; }
Copyright © 2005 |
Doug Gregor, Indiana University () Andrew Lumsdaine, Indiana University () |