ceph/src/boost/libs/graph/doc/sorted_erdos_renyi_gen.html

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   9       Authors: Jeremiah Willcock
  10                Douglas Gregor
  11                Andrew Lumsdaine
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  13 <Head>
  14   <Title>Boost Graph Library: Erd&ouml;s-Renyi Generator</Title>
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  31
  32 <tt>sorted_erdos_renyi_iterator</tt>
  33
  34 <br>
  35
  36 <PRE>
  37 template&lt;typename RandomGenerator, typename Graph&gt;
  38 class sorted_erdos_renyi_iterator
  39 {
  40 public:
  41   typedef std::input_iterator_tag iterator_category;
  42   typedef std::pair&lt;vertices_size_type, vertices_size_type&gt; value_type;
  43   typedef const value_type&amp; reference;
  44   typedef const value_type* pointer;
  45   typedef void difference_type;
  46
  47   sorted_erdos_renyi_iterator();
  48   sorted_erdos_renyi_iterator(RandomGenerator&amp; gen, vertices_size_type n,
  49                               double probability = 0.0, bool allow_self_loops = false);
  50
  51   // Iterator operations
  52   reference operator*() const;
  53   pointer operator-&gt;() const;
  54   sorted_erdos_renyi_iterator&amp; operator++();
  55   sorted_erdos_renyi_iterator operator++(int);
  56   bool operator==(const sorted_erdos_renyi_iterator&amp; other) const;
  57   bool operator!=(const sorted_erdos_renyi_iterator&amp; other) const;
  58 };
  59 </PRE>
  60
  61 <p> This class template implements a generator for Erd&ouml;s-Renyi
  62 graphs, suitable for initializing an <a
  63 href="adjacency_list.html"><tt>adjacency_list</tt></a> or other graph
  64 structure with iterator-based initialization. An Erd&ouml;s-Renyi
  65 graph <em>G = (n, p)</em> is a graph with <em>n</em> vertices
  66 such that the probability of having an edge <em>(u, v)</em> in <em>G</em>
  67 is <em>p</em> for any vertices <em>u</em> and <em>v</em>. Typically,
  68 there are no self-loops, but the generator can optionally introduce
  69 self-loops with probability <em>p</em>.</p>
  70
  71 <p>Erd&ouml;s-Renyi graphs typically exhibit very little
  72 structure. For this reason, they are rarely useful in modeling
  73 real-world problems. However, they are often used when determining
  74 the theoretical complexity of complex graph algorithms.</p>
  75
  76 <h3>Where Defined</h3>
  77
  78 <a href="../../../boost/graph/erdos_renyi_generator.hpp"><tt>boost/graph/erdos_renyi_generator.hpp</tt></a>
  79
  80 <h3>Constructors</h3>
  81
  82 <a name="default-constructor"/>
  83 <pre>sorted_erdos_renyi_iterator();</pre>
  84 <blockquote>
  85 Constructs a past-the-end iterator.
  86 </blockquote>
  87
  88 <pre>
  89 sorted_erdos_renyi_iterator(RandomGenerator&amp; gen, vertices_size_type n,
  90                             double probability = 0.0, bool allow_self_loops = false);
  91 </pre>
  92 <blockquote>
  93 Constructs an Erd&ouml;s-Renyi generator iterator that creates a
  94 graph with <tt>n</tt> vertices and a given <tt>probability</tt> of the
  95 total number of edges that a simple graph may have.
  96 Random vertices and edges are selected using the
  97 random number generator <tt>gen</tt>. Self-loops are permitted only when
  98 <tt>allow_self_loops</tt> is <tt>true</tt>.
  99 </blockquote>
 100
 101 <H3>Example</H3>
 102
 103 <pre>
 104 #include &lt;boost/graph/adjacency_list.hpp&gt;
 105 #include &lt;boost/graph/erdos_renyi_generator.hpp&gt;
 106 #include &lt;boost/random/linear_congruential.hpp&gt;
 107
 108 typedef boost::adjacency_list&lt;&gt; Graph;
 109 typedef boost::sorted_erdos_renyi_iterator&lt;boost::minstd_rand, Graph&gt; ERGen;
 110
 111 int main()
 112 {
 113   boost::minstd_rand gen;
 114   // Create graph with 100 nodes and edges with probability 0.05
 115   Graph g(ERGen(gen, 100, 0.05), ERGen(), 100);
 116   return 0;
 117 }
 118 </pre>
 119
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 122 <TABLE>
 123 <TR valign=top>
 124 <TD nowrap>Copyright &copy; 2005</TD><TD>
 125 Jeremiah Willcock, Indiana University (<script language="Javascript">address("cs.indiana.edu", "jewillco")</script>)<br>
 126
 127 <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>
 128   <A HREF="http://www.osl.iu.edu/~lums">Andrew Lumsdaine</A>,
 129 Indiana University (<script language="Javascript">address("osl.iu.edu", "lums")</script>)
 130 </TD></TR></TABLE>
 131
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