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// Copyright 2004, 2005 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)
// Authors: Nick Edmonds
// Andrew Lumsdaine
#ifndef BOOST_GRAPH_SSCA_GENERATOR_HPP
#define BOOST_GRAPH_SSCA_GENERATOR_HPP
#include <iterator>
#include <utility>
#include <vector>
#include <queue>
#include <boost/config.hpp>
#include <boost/random/uniform_int.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/type_traits/is_base_and_derived.hpp>
#include <boost/type_traits/is_same.hpp>
enum Direction {FORWARD = 1, BACKWARD = 2, BOTH = FORWARD | BACKWARD};
namespace boost {
// This generator generates graphs according to the method specified
// in SSCA 1.1. Current versions of SSCA use R-MAT graphs
template<typename RandomGenerator, typename Graph>
class ssca_iterator
{
typedef typename graph_traits<Graph>::directed_category directed_category;
typedef typename graph_traits<Graph>::vertices_size_type
vertices_size_type;
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;
// No argument constructor, set to terminating condition
ssca_iterator()
: gen(), verticesRemaining(0) { }
// Initialize for edge generation
ssca_iterator(RandomGenerator& gen, vertices_size_type totVertices,
vertices_size_type maxCliqueSize, double probUnidirectional,
int maxParallelEdges, double probIntercliqueEdges)
: gen(&gen), totVertices(totVertices), maxCliqueSize(maxCliqueSize),
probUnidirectional(probUnidirectional), maxParallelEdges(maxParallelEdges),
probIntercliqueEdges(probIntercliqueEdges), currentClique(0),
verticesRemaining(totVertices)
{
cliqueNum = std::vector<int>(totVertices, -1);
current = std::make_pair(0,0);
}
reference operator*() const { return current; }
pointer operator->() const { return ¤t; }
ssca_iterator& operator++()
{
BOOST_USING_STD_MIN();
while (values.empty() && verticesRemaining > 0) { // If there are no values left, generate a new clique
uniform_int<vertices_size_type> clique_size(1, maxCliqueSize);
uniform_int<vertices_size_type> rand_vertex(0, totVertices-1);
uniform_int<int> num_parallel_edges(1, maxParallelEdges);
uniform_int<short> direction(0,1);
uniform_01<RandomGenerator> prob(*gen);
std::vector<vertices_size_type> cliqueVertices;
cliqueVertices.clear();
vertices_size_type size = min BOOST_PREVENT_MACRO_SUBSTITUTION (clique_size(*gen), verticesRemaining);
while (cliqueVertices.size() < size) {
vertices_size_type v = rand_vertex(*gen);
if (cliqueNum[v] == -1) {
cliqueNum[v] = currentClique;
cliqueVertices.push_back(v);
verticesRemaining--;
}
} // Nick: This is inefficient when only a few vertices remain...
// I should probably just select the remaining vertices
// in order when only a certain fraction remain.
typename std::vector<vertices_size_type>::iterator first, second;
for (first = cliqueVertices.begin(); first != cliqueVertices.end(); ++first)
for (second = first+1; second != cliqueVertices.end(); ++second) {
Direction d;
int edges;
d = prob() < probUnidirectional ? (direction(*gen) == 0 ? FORWARD : BACKWARD) : BOTH;
if (d & FORWARD) {
edges = num_parallel_edges(*gen);
for (int i = 0; i < edges; ++i)
values.push(std::make_pair(*first, *second));
}
if (d & BACKWARD) {
edges = num_parallel_edges(*gen);
for (int i = 0; i < edges; ++i)
values.push(std::make_pair(*second, *first));
}
}
if (verticesRemaining == 0) {
// Generate interclique edges
for (vertices_size_type i = 0; i < totVertices; ++i) {
double p = probIntercliqueEdges;
for (vertices_size_type d = 2; d < totVertices/2; d *= 2, p/= 2) {
vertices_size_type j = (i+d) % totVertices;
if (cliqueNum[j] != cliqueNum[i] && prob() < p) {
int edges = num_parallel_edges(*gen);
for (int i = 0; i < edges; ++i)
values.push(std::make_pair(i, j));
}
}
}
}
currentClique++;
}
if (!values.empty()) { // If we're not done return a value
current = values.front();
values.pop();
}
return *this;
}
ssca_iterator operator++(int)
{
ssca_iterator temp(*this);
++(*this);
return temp;
}
bool operator==(const ssca_iterator& other) const
{
return verticesRemaining == other.verticesRemaining && values.empty() && other.values.empty();
}
bool operator!=(const ssca_iterator& other) const
{ return !(*this == other); }
private:
// Parameters
RandomGenerator* gen;
vertices_size_type totVertices;
vertices_size_type maxCliqueSize;
double probUnidirectional;
int maxParallelEdges;
double probIntercliqueEdges;
// Internal data structures
std::vector<int> cliqueNum;
std::queue<value_type> values;
int currentClique;
vertices_size_type verticesRemaining;
value_type current;
};
} // end namespace boost
#endif // BOOST_GRAPH_SSCA_GENERATOR_HPP
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