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317 lines
11 KiB
C++
317 lines
11 KiB
C++
//=======================================================================
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// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
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// Copyright 2004, 2005 Trustees of Indiana University
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// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek,
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// Doug Gregor, D. Kevin McGrath
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//=======================================================================//
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#ifndef BOOST_GRAPH_KING_HPP
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#define BOOST_GRAPH_KING_HPP
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#include <boost/config.hpp>
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#include <boost/graph/detail/sparse_ordering.hpp>
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#include <boost/graph/graph_utility.hpp>
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/*
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King Algorithm for matrix reordering
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*/
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namespace boost {
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namespace detail {
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template<typename OutputIterator, typename Buffer, typename Compare,
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typename PseudoDegreeMap, typename VecMap, typename VertexIndexMap>
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class bfs_king_visitor:public default_bfs_visitor
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{
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public:
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bfs_king_visitor(OutputIterator *iter, Buffer *b, Compare compare,
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PseudoDegreeMap deg, std::vector<int> loc, VecMap color,
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VertexIndexMap vertices):
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permutation(iter), Qptr(b), degree(deg), comp(compare),
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Qlocation(loc), colors(color), vertex_map(vertices) { }
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template <typename Vertex, typename Graph>
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void finish_vertex(Vertex, Graph& g) {
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typename graph_traits<Graph>::out_edge_iterator ei, ei_end;
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Vertex v, w;
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typedef typename std::deque<Vertex>::reverse_iterator reverse_iterator;
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reverse_iterator rend = Qptr->rend()-index_begin;
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reverse_iterator rbegin = Qptr->rbegin();
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//heap the vertices already there
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std::make_heap(rbegin, rend, boost::bind<bool>(comp, _2, _1));
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unsigned i = 0;
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for(i = index_begin; i != Qptr->size(); ++i){
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colors[get(vertex_map, (*Qptr)[i])] = 1;
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Qlocation[get(vertex_map, (*Qptr)[i])] = i;
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}
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i = 0;
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for( ; rbegin != rend; rend--){
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percolate_down<Vertex>(i);
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w = (*Qptr)[index_begin+i];
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for (boost::tie(ei, ei_end) = out_edges(w, g); ei != ei_end; ++ei) {
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v = target(*ei, g);
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put(degree, v, get(degree, v) - 1);
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if (colors[get(vertex_map, v)] == 1) {
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percolate_up<Vertex>(get(vertex_map, v), i);
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}
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}
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colors[get(vertex_map, w)] = 0;
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i++;
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}
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}
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template <typename Vertex, typename Graph>
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void examine_vertex(Vertex u, const Graph&) {
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*(*permutation)++ = u;
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index_begin = Qptr->size();
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}
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protected:
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//this function replaces pop_heap, and tracks state information
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template <typename Vertex>
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void percolate_down(int offset){
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int heap_last = index_begin + offset;
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int heap_first = Qptr->size() - 1;
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//pop_heap functionality:
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//swap first, last
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std::swap((*Qptr)[heap_last], (*Qptr)[heap_first]);
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//swap in the location queue
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std::swap(Qlocation[heap_first], Qlocation[heap_last]);
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//set drifter, children
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int drifter = heap_first;
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int drifter_heap = Qptr->size() - drifter;
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int right_child_heap = drifter_heap * 2 + 1;
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int right_child = Qptr->size() - right_child_heap;
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int left_child_heap = drifter_heap * 2;
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int left_child = Qptr->size() - left_child_heap;
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//check that we are staying in the heap
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bool valid = (right_child < heap_last) ? false : true;
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//pick smallest child of drifter, and keep in mind there might only be left child
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int smallest_child = (valid && get(degree, (*Qptr)[left_child]) > get(degree,(*Qptr)[right_child])) ?
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right_child : left_child;
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while(valid && smallest_child < heap_last && comp((*Qptr)[drifter], (*Qptr)[smallest_child])){
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//if smallest child smaller than drifter, swap them
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std::swap((*Qptr)[smallest_child], (*Qptr)[drifter]);
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std::swap(Qlocation[drifter], Qlocation[smallest_child]);
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//update the values, run again, as necessary
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drifter = smallest_child;
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drifter_heap = Qptr->size() - drifter;
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right_child_heap = drifter_heap * 2 + 1;
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right_child = Qptr->size() - right_child_heap;
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left_child_heap = drifter_heap * 2;
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left_child = Qptr->size() - left_child_heap;
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valid = (right_child < heap_last) ? false : true;
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smallest_child = (valid && get(degree, (*Qptr)[left_child]) > get(degree,(*Qptr)[right_child])) ?
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right_child : left_child;
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}
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}
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// this is like percolate down, but we always compare against the
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// parent, as there is only a single choice
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template <typename Vertex>
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void percolate_up(int vertex, int offset){
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int child_location = Qlocation[vertex];
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int heap_child_location = Qptr->size() - child_location;
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int heap_parent_location = (int)(heap_child_location/2);
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unsigned parent_location = Qptr->size() - heap_parent_location;
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bool valid = (heap_parent_location != 0 && child_location > index_begin + offset &&
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parent_location < Qptr->size());
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while(valid && comp((*Qptr)[child_location], (*Qptr)[parent_location])){
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//swap in the heap
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std::swap((*Qptr)[child_location], (*Qptr)[parent_location]);
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//swap in the location queue
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std::swap(Qlocation[child_location], Qlocation[parent_location]);
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child_location = parent_location;
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heap_child_location = heap_parent_location;
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heap_parent_location = (int)(heap_child_location/2);
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parent_location = Qptr->size() - heap_parent_location;
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valid = (heap_parent_location != 0 && child_location > index_begin + offset);
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}
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}
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OutputIterator *permutation;
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int index_begin;
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Buffer *Qptr;
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PseudoDegreeMap degree;
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Compare comp;
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std::vector<int> Qlocation;
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VecMap colors;
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VertexIndexMap vertex_map;
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};
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} // namespace detail
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template<class Graph, class OutputIterator, class ColorMap, class DegreeMap,
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typename VertexIndexMap>
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OutputIterator
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king_ordering(const Graph& g,
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std::deque< typename graph_traits<Graph>::vertex_descriptor >
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vertex_queue,
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OutputIterator permutation,
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ColorMap color, DegreeMap degree,
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VertexIndexMap index_map)
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{
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typedef typename property_traits<DegreeMap>::value_type ds_type;
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typedef typename property_traits<ColorMap>::value_type ColorValue;
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typedef color_traits<ColorValue> Color;
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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typedef iterator_property_map<typename std::vector<ds_type>::iterator, VertexIndexMap, ds_type, ds_type&> PseudoDegreeMap;
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typedef indirect_cmp<PseudoDegreeMap, std::less<ds_type> > Compare;
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typedef typename boost::sparse::sparse_ordering_queue<Vertex> queue;
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typedef typename detail::bfs_king_visitor<OutputIterator, queue, Compare,
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PseudoDegreeMap, std::vector<int>, VertexIndexMap > Visitor;
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typedef typename graph_traits<Graph>::vertices_size_type
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vertices_size_type;
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std::vector<ds_type> pseudo_degree_vec(num_vertices(g));
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PseudoDegreeMap pseudo_degree(pseudo_degree_vec.begin(), index_map);
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typename graph_traits<Graph>::vertex_iterator ui, ui_end;
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queue Q;
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// Copy degree to pseudo_degree
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// initialize the color map
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for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui){
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put(pseudo_degree, *ui, get(degree, *ui));
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put(color, *ui, Color::white());
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}
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Compare comp(pseudo_degree);
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std::vector<int> colors(num_vertices(g));
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for(vertices_size_type i = 0; i < num_vertices(g); i++)
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colors[i] = 0;
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std::vector<int> loc(num_vertices(g));
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//create the visitor
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Visitor vis(&permutation, &Q, comp, pseudo_degree, loc, colors, index_map);
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while( !vertex_queue.empty() ) {
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Vertex s = vertex_queue.front();
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vertex_queue.pop_front();
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//call BFS with visitor
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breadth_first_visit(g, s, Q, vis, color);
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}
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return permutation;
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}
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// This is the case where only a single starting vertex is supplied.
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template <class Graph, class OutputIterator,
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class ColorMap, class DegreeMap, typename VertexIndexMap>
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OutputIterator
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king_ordering(const Graph& g,
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typename graph_traits<Graph>::vertex_descriptor s,
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OutputIterator permutation,
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ColorMap color, DegreeMap degree, VertexIndexMap index_map)
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{
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std::deque< typename graph_traits<Graph>::vertex_descriptor > vertex_queue;
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vertex_queue.push_front( s );
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return king_ordering(g, vertex_queue, permutation, color, degree,
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index_map);
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}
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template < class Graph, class OutputIterator,
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class ColorMap, class DegreeMap, class VertexIndexMap>
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OutputIterator
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king_ordering(const Graph& G, OutputIterator permutation,
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ColorMap color, DegreeMap degree, VertexIndexMap index_map)
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{
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if (has_no_vertices(G))
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return permutation;
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typedef typename boost::graph_traits<Graph>::vertex_descriptor Vertex;
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typedef typename property_traits<ColorMap>::value_type ColorValue;
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typedef color_traits<ColorValue> Color;
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std::deque<Vertex> vertex_queue;
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// Mark everything white
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BGL_FORALL_VERTICES_T(v, G, Graph) put(color, v, Color::white());
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// Find one vertex from each connected component
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BGL_FORALL_VERTICES_T(v, G, Graph) {
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if (get(color, v) == Color::white()) {
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depth_first_visit(G, v, dfs_visitor<>(), color);
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vertex_queue.push_back(v);
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}
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}
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// Find starting nodes for all vertices
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// TBD: How to do this with a directed graph?
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for (typename std::deque<Vertex>::iterator i = vertex_queue.begin();
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i != vertex_queue.end(); ++i)
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*i = find_starting_node(G, *i, color, degree);
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return king_ordering(G, vertex_queue, permutation, color, degree,
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index_map);
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}
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template<typename Graph, typename OutputIterator, typename VertexIndexMap>
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OutputIterator
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king_ordering(const Graph& G, OutputIterator permutation,
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VertexIndexMap index_map)
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{
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if (has_no_vertices(G))
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return permutation;
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std::vector<default_color_type> colors(num_vertices(G));
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return king_ordering(G, permutation,
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make_iterator_property_map(&colors[0], index_map,
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colors[0]),
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make_out_degree_map(G), index_map);
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}
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template<typename Graph, typename OutputIterator>
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inline OutputIterator
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king_ordering(const Graph& G, OutputIterator permutation)
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{ return king_ordering(G, permutation, get(vertex_index, G)); }
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} // namespace boost
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#endif // BOOST_GRAPH_KING_HPP
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