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| Andrew Lumsdaine |
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| <Head> |
| <Title>Boost Graph Library: Small World Generator</Title> |
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| |
| <tt>small_world_iterator</tt> |
| |
| <br> |
| |
| <PRE> |
| template<typename RandomGenerator, typename Graph> |
| class small_world_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; |
| |
| small_world_iterator(); |
| small_world_iterator(RandomGenerator& gen, vertices_size_type n, |
| vertices_size_type k, double probability, |
| bool allow_self_loops = false); |
| // Iterator operations |
| reference operator*() const; |
| pointer operator->() const; |
| small_world_iterator& operator++(); |
| small_world_iterator operator++(int); |
| bool operator==(const small_world_iterator& other) const; |
| bool operator!=(const small_world_iterator& other) const; |
| }; |
| </PRE> |
| |
| <p> This class template implements a generator for small-world graphs, |
| suitable for initializing an <a |
| href="adjacency_list.html"><tt>adjacency_list</tt></a> or other graph |
| structure with iterator-based initialization. A small-world graph |
| consists of a ring graph (where each vertex is connected to its |
| <em>k</em> nearest neighbors). Edges in the graph are randomly |
| rewired to different vertices with a probability |
| <em>p</em>. Small-world graphs exhibit a high clustering coefficient |
| (because vertices are always connected to their closest neighbors), |
| but rewiring ensures a small diameter.</p> |
| |
| <h3>Where Defined</h3> |
| |
| <a href="../../../boost/graph/small_world_generator.hpp"><tt>boost/graph/small_world_generator.hpp</tt></a> |
| |
| <h3>Constructors</h3> |
| |
| <a name="default-constructor"/> |
| <pre>small_world_iterator();</pre> |
| <blockquote> |
| Constructs a past-the-end iterator. |
| </blockquote> |
| |
| <pre> |
| small_world_iterator(RandomGenerator& gen, vertices_size_type n, |
| vertices_size_type k, double probability, |
| bool allow_self_loops = false); |
| </pre> |
| <blockquote> |
| Constructs a small-world generator iterator that creates a |
| graph with <tt>n</tt> vertices, each connected to its <tt>k</tt> |
| nearest neighbors. Probabilities are drawn from the |
| random number generator <tt>gen</tt>. Self-loops are permitted only |
| when <tt>allow_self_loops</tt> is <tt>true</tt>. |
| </blockquote> |
| |
| <H3>Example</H3> |
| |
| <pre> |
| #include <boost/graph/adjacency_list.hpp> |
| #include <boost/graph/small_world_generator.hpp> |
| #include <boost/random/linear_congruential.hpp> |
| |
| typedef boost::adjacency_list<> Graph; |
| typedef boost::small_world_iterator<boost::minstd_rand, Graph> SWGen; |
| |
| int main() |
| { |
| boost::minstd_rand gen; |
| // Create graph with 100 nodes |
| Graph g(SWGen(gen, 100, 6, 0.03), SWGen(), 100); |
| return 0; |
| } |
| </pre> |
| |
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| <TABLE> |
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| <TD nowrap>Copyright © 2005</TD><TD> |
| <A HREF="http://www.boost.org/people/doug_gregor.html">Doug Gregor</A>, Indiana University (<script language="Javascript">address("cs.indiana.edu", "dgregor")</script>)<br> |
| <A HREF="http://www.osl.iu.edu/~lums">Andrew Lumsdaine</A>, |
| Indiana University (<script language="Javascript">address("osl.iu.edu", "lums")</script>) |
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