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graphutil.cpp
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graphutil.cpp
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//=======================================================================
// Copyright 2015 - 2020 Jeff Linahan
//
// Distributed under 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)
//=======================================================================
#include "graphutil.h"
#include "BFSVisitorData.h"
#include "strutil.h"
#include <boost/graph/make_biconnected_planar.hpp>
#include <boost/graph/make_maximal_planar.hpp>
#include <boost/algorithm/string.hpp>
#include <boost/lexical_cast.hpp>
#include <iostream>
#include <fstream>
using namespace std;
using namespace boost;
int levi_civita(uint i, uint j, uint k)
{
if( i == j || j == k || k == i ) return 0;
if( i == 1 && j == 2 && k == 3 ) return 1;
if( i == 2 && j == 3 && k == 1 ) return 1;
if( i == 3 && j == 1 && k == 2 ) return 1;
return -1;
}
void init_vert_propmap(Graph& g)
{
auto prop_map = get(vertex_index, g); // writing to this property map has side effects in the graph
VertIter vi, vend;
uint i = 0;
for( tie(vi, vend) = vertices(g); vi != vend; ++vi ){
#ifdef GRAPH_TYPE_VEC
abort();
#else
prop_map[*vi] = i;
#endif
cout << "prop map " << *vi << " == " << i << '\n';
++i;
}
}
vertex_t get_common_ancestor(vector<vertex_t> const& ancestors_v, vector<vertex_t> const& ancestors_w)
{
for( uint i = 0; i < ancestors_v.size(); ++i ){
for( uint j = 0; j < ancestors_w.size(); ++j ){
if( ancestors_v[i] == ancestors_w[j] ) return ancestors_v[i];
}
}
return Graph::null_vertex();
}
// return set of vertices neighboring v in graph g
set<vertex_t> get_neighbors(vertex_t v, Graph const& g)
{
set<vertex_t> neighbors;
OutEdgeIter e_cur, e_end;
for( tie(e_cur, e_end) = out_edges(v, g); e_cur != e_end; ++e_cur ){
auto n = target(*e_cur, g);
neighbors.insert(n);
//cout << " vertex " << vmap.vert2uint[v] << " has neighbor " << vmap.vert2uint[n] << '\n';
}
return neighbors;
}
// get set intersection of a and b
set<vertex_t> get_intersection(set<vertex_t> const& a, set<vertex_t> const& b)
{
set<vertex_t> c;
set_intersection(STLALL(a), STLALL(b), inserter(c, c.begin()));
//for( auto& i : c ) cout << " set intersection: " << vmap.vert2uint[i] << '\n';
return c;
}
/* Given an edge e and a cycle of vertices, determine whether e is in inside, outside, or on the cycle.
An embedding is needed to establish what is inside and outside.
e may be anywhere on the graph.
common_vert_on_cycle should be a tree vertex that both of e's incident vertices share as an ancestor */
InsideOutOn is_edge_inside_outside_or_on_cycle(edge_t e, vertex_t common_vert_on_cycle, vector<vertex_t> const& cycle, Graph const& g, Embedding const& em)
{
cout << "------------------ is edge inside outside or on cycle -----------------\n";
cout << "is edge inside outside or on cycle? " << to_string(e, g) << '\n';
//cout << "edge: " << vmap.vert2uint[source(e, g)] << ' ' << vmap.vert2uint[target(e, g)] << '\n';
//cout << "cycle: ";
//for( uint i = 0; i < cycle.size(); ++i ) cout << vmap.vert2uint[cycle[i]] << ' ';
//cout << '\n';
auto src = source(e, g);
auto tar = target(e, g);
if( on_cycle(e, cycle, g) ){
cout << "edge is on cycle\n";
return ON;
}
//cout << " testing if edge " << vmap.vert2uint[src] << ", " << vmap.vert2uint[tar] << " is inside or outside the cycle\n";
//cout << " common_vert_on_cycle: " << vmap.vert2uint[common_vert_on_cycle] << '\n';
auto it = find(STLALL(cycle), common_vert_on_cycle);
if( it == cycle.end() ){ cout << " common_vert_on_cycle needs to appear in cycle\n"; BOOST_ASSERT(0); }
BOOST_ASSERT(*it == common_vert_on_cycle);
auto before_common = it == cycle.begin() ? cycle.end ()-1 : it-1;
auto after_common = it+1 == cycle.end () ? cycle.begin() : it+1;
auto other_end_of_common = source(e, g) == common_vert_on_cycle ? target(e, g) : source(e, g);
/*cout << '\n';
cout << " it: " << vmap.vert2uint[*it] << '\n';
cout << " v: " << vmap.vert2uint[common_vert_on_cycle] << '\n';
cout << " before: " << vmap.vert2uint[*before_common] << '\n';
cout << " after: " << vmap.vert2uint[*after_common] << '\n';
cout << " other: " << vmap.vert2uint[other_end_of_common] << '\n';*/
vector<uint> permu;
set<vertex_t> seenbefore;
for( auto& edge : em[*it] ){ // why does this contain duplicates?
auto src = source(edge, g);
auto tar = target(edge, g);
if( src != common_vert_on_cycle ) swap(src, tar);
BOOST_ASSERT(src == common_vert_on_cycle);
//cout << " tar: " << vmap.vert2uint[tar] << '\n';
if( seenbefore.find(tar) != seenbefore.end() ) continue;
seenbefore.insert(tar);
// this can't be an if-else ladder because sometimes other, before, and after equal each other and we wouldn't have 3 permutations
if( tar == other_end_of_common ) permu.push_back(1);
if( tar == *before_common ) permu.push_back(2);
if( tar == *after_common ) permu.push_back(3);
}
BOOST_ASSERT(permu.size() == 3);
return levi_civita(permu[0], permu[1], permu[2]) == 1 ?
INSIDE :
OUTSIDE;
}
// scan edges around all vertices of cycle and add up edge costs
CycleCost compute_cycle_cost(vector<vertex_t> const& cycle, Graph const& g, BFSVisitorData const& vis_data, EmbedStruct const& em)
{
CycleCost cc;
for( auto& v : cycle ){
cout << " scanning cycle vert " << v << '\n';
for( auto e = out_edges(v, g); e.first != e.second; ++e.first ){
if( vis_data.is_tree_edge(*e.first) ){
if( !on_cycle(*e.first, cycle, g) ){
uint cost = vis_data.edge_cost(*e.first, cycle, g);
//uint vert_id = vmap.vert2uint[v];
//cout << " scanning incident tree edge " << vert_id << " cost: " << cost << '\n';
auto insideout = is_edge_inside_outside_or_on_cycle(*e.first, v, cycle, g, em.em);
BOOST_ASSERT(insideout != ON);
bool is_inside = (insideout == INSIDE);
(is_inside ? cc.inside : cc.outside) += cost;
}
}
}
}
return cc;
}
// Make all faces of graph G into triangles by adding scanning the boundary and adding (nontree) edges as necessary
EmbedStruct make_max_planar(Graph& g)
{
EdgeIndex i = reset_edge_index(g);
EmbedStruct em(&g);
BOOST_ASSERT(em.test_planar());
make_biconnected_planar(g, em.em, i);
reset_edge_index(g);
BOOST_ASSERT(em.test_planar());
make_maximal_planar(g, em.em);
reset_edge_index(g);
BOOST_ASSERT(em.test_planar());
return em;
}
void reset_vertex_indices(Graph& g)
{
VertIter vi, vend;
uint i = 0;
for( tie(vi, vend) = vertices(g); vi != vend; ++vi, ++i ){
put(vertex_index, g, *vi, i);
}
}
EdgeIndex reset_edge_index(Graph const& g)
{
EdgeIndex edgedesc_to_uint;
EdgesSizeType edge_num = 0;
EdgeIter ei, ei_end;
for( tie(ei, ei_end) = edges(g); ei != ei_end; ++ei ){
edgedesc_to_uint[*ei] = edge_num++;
}
return edgedesc_to_uint;
}
struct CantContractVertexWithSelf
{
};
// replace a and b with a single vertex that has edges to all of their neighbors
vertex_t contract_vertices(vertex_t a, vertex_t b, Graph& g)
{
if( a == b ) throw CantContractVertexWithSelf();
auto be = adjacent_vertices(b, g);
for( auto beit = be.first; beit != be.second; ++beit ) if( *beit != a ) add_edge(a, *beit, g);
remove_vertex(b, g);
return a;
}
void kill_vertex(vertex_t v, Graph& g)
{
//cout << "killing vertex " << i << '\n';
clear_vertex(v, g);
remove_vertex(v, g);
}
struct FileNotFound {};
Graph load_graph(string const& fname)
{
ifstream in(fname);
if( !in ){
cerr << "file \"in\" not found!\n";
throw FileNotFound();
}
string str;
vector<pair<uint, uint>> file_edges;
int max_v = -1;
while( getline(in, str) ){
uint colon = str.find(",");
string stra = str.substr(0, colon); trim(stra);
string strb = str.substr(colon+1 ); trim(strb);
int a = lexical_cast<int>(stra);
int b = lexical_cast<int>(strb);
max_v = max(max(max_v, a), b);
file_edges.push_back({a, b});
}
Graph g(max_v+1);
map<uint, vertex_t> uint_to_vert;
VertIter vi, vi_end;
uint i = 0;
for( tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi ){
//put(vertex_index, g, *vi, i);
uint_to_vert[i] = *vi;
++i;
}
for( pair<uint, uint>& e : file_edges ){
auto src = uint_to_vert[e.first];
auto tar = uint_to_vert[e.second];
add_edge(src, tar, g);
}
return g;
}
bool vertex_exists(vertex_t x, Graph const& g)
{
VertIter vi, vi_end;
for( tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi) {
if( *vi == x ) return true;
}
return false;
}
bool edge_exists(edge_t e, Graph const& g)
{
EdgeIter ei, ei_end;
for( tie(ei, ei_end) = edges(g); ei != ei_end; ++ei ){
if( *ei == e ) return true;
}
return false;
}
bool assert_verts(GraphCR g, BFSVisitorData const& vis_data)
{
VertIter vei, vend;
for( tie(vei, vend) = vertices(g); vei != vend; ++vei ){
vertex_t v = *vei;
if( !vis_data.verts.contains(v) ){
cout << "graphutils.cpp: ignoring bad vertex : " << v << '\n';
return false;
}
}
return true;
}