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  <Title>Boost Graph Library: Small World Generator</Title>
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<tt>small_world_iterator</tt>

<br>

<PRE>
template&lt;typename RandomGenerator, typename Graph&gt;
class small_world_iterator
{
public:
  typedef std::input_iterator_tag iterator_category;
  typedef std::pair&lt;vertices_size_type, vertices_size_type&gt; value_type;
  typedef const value_type&amp; reference;
  typedef const value_type* pointer;
  typedef void difference_type;

  small_world_iterator();
  small_world_iterator(RandomGenerator&amp; gen, vertices_size_type n,
                       vertices_size_type k, double probability,
                       bool allow_self_loops = false);
  // Iterator operations
  reference operator*() const;
  pointer operator-&gt;() const;
  small_world_iterator&amp; operator++();
  small_world_iterator operator++(int);
  bool operator==(const small_world_iterator&amp; other) const;
  bool operator!=(const small_world_iterator&amp; 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&amp; 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 &lt;boost/graph/adjacency_list.hpp&gt;
#include &lt;boost/graph/small_world_generator.hpp&gt;
#include &lt;boost/random/linear_congruential.hpp&gt;

typedef boost::adjacency_list&lt;&gt; Graph;
typedef boost::small_world_iterator&lt;boost::minstd_rand, Graph&gt; 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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<TD nowrap>Copyright &copy; 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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