.. Copyright (C) 2004-2009 The Trustees of Indiana University.
   Use, modification and distribution is subject to the Boost Software
   License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   http://www.boost.org/LICENSE_1_0.txt)

===================================
|Logo| Unique R-MAT generator
===================================

::
 
  template<typename RandomGenerator, typename Graph>
  class unique_rmat_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;

    unique_rmat_iterator();
    unique_rmat_iterator(RandomGenerator& gen, vertices_size_type n, 
                  edges_size_type m, double a, double b, double c, 
                  double d, bool permute_vertices = true);
    // Iterator operations
    reference operator*() const;
    pointer operator->() const;
    unique_rmat_iterator& operator++();
    unique_rmat_iterator operator++(int);
    bool operator==(const unique_rmat_iterator& other) const;
    bool operator!=(const unique_rmat_iterator& other) const;
 };

This class template implements a generator for R-MAT graphs [CZF04]_,
suitable for initializing an adjacency_list or other graph structure
with iterator-based initialization. An R-MAT graph has a scale-free
distribution w.r.t. vertex degree and is implemented using
Recursive-MATrix partitioning.  The edge list produced by this iterator
is guaranteed not to contain parallel edges.

Where Defined
-------------
<``boost/graph/rmat_graph_generator.hpp``>

Constructors
------------

::

  unique_rmat_iterator();

Constructs a past-the-end iterator.

::

  unique_rmat_iterator(RandomGenerator& gen, vertices_size_type n, 
                       edges_size_type m, double a, double b, double c, 
                       double d, bool permute_vertices = true,
                       EdgePredicate ep = keep_all_edges());

Constructs an R-MAT generator iterator that creates a graph with ``n``
vertices and ``m`` edges.  ``a``, ``b``, ``c``, and ``d`` represent
the probability that a generated edge is placed of each of the 4
quadrants of the partitioned adjacency matrix.  Probabilities are
drawn from the random number generator ``gen``.  Vertex indices are
permuted to eliminate locality when ``permute_vertices`` is true.
``ep`` allows the user to specify which edges are retained, this is
useful in the case where the user wishes to refrain from storing
remote edges locally during generation to reduce memory consumption.

Example
-------

::

  #include <boost/graph/adjacency_list.hpp>
  #include <boost/graph/rmat_graph_generator.hpp>
  #include <boost/random/linear_congruential.hpp>

  typedef boost::adjacency_list<> Graph;
  typedef boost::unique_rmat_iterator<boost::minstd_rand, Graph> RMATGen;

  int main()
  {
    boost::minstd_rand gen;
    // Create graph with 100 nodes and 400 edges 
    Graph g(RMATGen(gen, 100, 400, 0.57, 0.19, 0.19, 0.05,), 
            RMATGen(), 100);
    return 0;
  }


Bibliography
------------

.. [CZF04] D Chakrabarti, Y Zhan, and C Faloutsos.  R-MAT: A Recursive
  Model for Graph Mining. In Proceedings of 4th International Conference
  on Data Mining, pages 442--446, 2004.

-----------------------------------------------------------------------------

Copyright (C) 2009 The Trustees of Indiana University.

Authors: Nick Edmonds and Andrew Lumsdaine

.. |Logo| image:: pbgl-logo.png
            :align: middle
            :alt: Parallel BGL
            :target: http://www.osl.iu.edu/research/pbgl