/usr/include/opengm/inference/auxiliary/planar_graph.hxx is in libopengm-dev 2.3.6-2.
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#ifndef OPENGM_PLANAR_GRAPH_HXX
#define OPENGM_PLANAR_GRAPH_HXX
#include <iostream>
#include <vector>
#include <stack>
#include <list>
#include "opengm/opengm.hxx"
//TODO: Fix include path
#include <planarity.src-patched/graph.h>
#include <planarity.src-patched/listcoll.h>
#include <planarity.src-patched/stack.h>
#include <planarity.src-patched/appconst.h>
#include <blossom5.src-patched/PerfectMatching.h>
#include <blossom5.src-patched/PMimplementation.h>
#include <blossom5.src-patched/MinCost/MinCost.h>
namespace opengm {
namespace external {
namespace planargraph {
typedef double DataType;
//////////////////////////////////////////////////////
// PlanarGraph components
//////////////////////////////////////////////////////
struct Node
{
Node() : weight(0.0), adj(0) {};
// Node weight
// Unused (0.0) for dual edges
// do zrobienia: make node class a template class and only use weight in reweighted_planar_max_cut
DataType weight;
// List of indices of the dual edges
std::list<size_t> adj;
};
struct Edge
{
Edge()
: tail(0), head(0), weight(0.0), left_face(-1), right_face(-1) {};
// Indices of tail and head node
size_t tail;
size_t head;
// Edge weight
DataType weight;
// Indices of left and right face (as seen from head to tail).
// -1 if unassigned
int left_face;
int right_face;
};
struct Face
{
Face() : edges(0), dual_nodes(0) {};
// List of edges surrounding the face. Is in sorted order (s.t. the
// edges form an orbit) after calling planarize()
std::list<size_t> edges;
// List of the dual nodes_ (forming a clique) belonging to this face
std::list<size_t> dual_nodes;
};
//////////////////////////////////////////////////////
// PlanarGraph class definition
//////////////////////////////////////////////////////
class PlanarGraph
{
public:
PlanarGraph();
PlanarGraph(size_t n, bool debug);
~PlanarGraph();
size_t num_nodes() const { return nodes_.size(); };
size_t num_edges() const { return edges.size(); };
size_t num_faces() const { return faces.size(); };
size_t add_node();
long int find_edge(size_t u, size_t v) const;
size_t add_edge(size_t u, size_t v, DataType w);
void add_edge_weight(size_t e, DataType w);
void print();
void planarize();
void construct_dual();
void get_labeling(std::vector<int> & x) const;
void calculate_maxcut();
std::vector<bool> get_cut() const;
std::vector<int> get_labeling_from_cut(const std::vector<bool>& cut) const;
double cost_of_cut(const std::vector<int>& x) const;
double cost_of_cut() const;
protected:
long int get_dest(size_t v, size_t e) const;
long int get_following_edge(size_t v, size_t e) const;
void clear_faces();
size_t compute_dual_num_edges() const;
std::vector<Node> nodes_;
std::vector<Edge> edges;
std::vector<Face> faces;
//std::unique_ptr<PerfectMatching> Dual_;
PerfectMatching* Dual_;
bool debug_;
};
//////////////////////////////////////////////////////
// Basic functionality
//////////////////////////////////////////////////////
//
PlanarGraph::PlanarGraph()
: nodes_(0), edges (0), faces(0), Dual_(NULL), debug_(false)
// : nodes_(0), edges (0), faces(0), Dual_(nullptr), debug_(debug)
{
nodes_.reserve(0);
edges.reserve(0);
}
PlanarGraph::PlanarGraph(size_t n, bool debug = false)
: nodes_(0), edges (0), faces(0), Dual_(NULL), debug_(debug)
// : nodes_(0), edges (0), faces(0), Dual_(nullptr), debug_(debug)
{
nodes_.reserve(n);
edges.reserve(3*n);
}
PlanarGraph::~PlanarGraph(){
if(Dual_ != NULL)
delete Dual_;
}
// Adds a new node with weight w to the graph
size_t PlanarGraph::add_node()
{
// Create new node object (in place) and set its weight
size_t v = nodes_.size();
nodes_.resize(v+1);
// Return index of the new node
return v;
}
// Adds new edge with weight w between nodes_ u and v
size_t PlanarGraph::add_edge(size_t u, size_t v, DataType w)
{
// Check that u and v are valid node indices
OPENGM_ASSERT(u >= 0 && u<nodes_.size());
OPENGM_ASSERT(v >= 0 && v<nodes_.size());
// Create new edge object (in place) and set properties
size_t e = edges.size();
edges.resize(e+1);
edges[e].tail = u;
edges[e].head = v;
edges[e].weight = w;
// Add edge index to both nodes_' adjacency lists
nodes_[u].adj.push_back(e);
nodes_[v].adj.push_back(e);
// Return index of the new edge
return e;
}
// Adds weight w to the existing edge e
void PlanarGraph::add_edge_weight(size_t e, DataType w)
{
// Check the e is a valid edge index
OPENGM_ASSERT(e >= 0 && e < edges.size());
edges[e].weight = w;
}
// Returns index of the edge connecting nodes_ u and v
// -1 if such an edge does not exist
long int PlanarGraph::find_edge(size_t u, size_t v) const
{
// Search u's adjacency list for an edge connecting it to v.
for(size_t e=0; e<nodes_[u].adj.size(); ++e)
{
if( edges[e].tail==v || edges[e].head==v )
{
return e;
}
}
// Return -1 if the loop did not find one.
return -1;
}
// Returns index of the destination node of Edge e as seen from node v
// -1 if e is not incident on v
long int PlanarGraph::get_dest(size_t v, size_t e) const
{
if(v == edges[e].tail)
return edges[e].head;
else if (v == edges[e].head)
return edges[e].tail;
else
return -1;
}
// Simple command line output of the graph for debugging
void PlanarGraph::print()
{
if(debug_)
std::cout << "PlanarGraph with " << num_nodes() << " nodes_, "
<< num_edges() << " edges and " << num_faces() << " faces.\n";
for(size_t u = 0; u<nodes_.size(); ++u)
{
// Print current node's id and weight
if(debug_)
std::cout << u << "\t[" << nodes_[u].weight << "]:\t";
// For all edges in current node's adjacency list
for(std::list<size_t>::iterator it = nodes_[u].adj.begin();
it != nodes_[u].adj.end(); ++it)
{
// Get the destination of the current edge
// Print destination id and weight of the edge
size_t v = get_dest(u, *it);
if(debug_)
std::cout << v << " (" << edges[*it].weight << "), ";
}
if(debug_)
std::cout << "\n";
}
}
//////////////////////////////////////////////////////
// Construction of planar embedding
//////////////////////////////////////////////////////
// Returns the index of the edge that succeeds e in v's adjacency list
// -1 if e is not incident on v
long int PlanarGraph::get_following_edge(size_t v, size_t e) const
{
// Iterate to e in v's adjacency list
std::list<size_t>::const_iterator it = nodes_[v].adj.begin();
while((*it != e) && (it != nodes_[v].adj.end()))
++it;
if(it==nodes_[v].adj.end()) // e is not in v's adj list
{
return -1;
}
else // e is in v's adj list
{
++it; // Make one more step
if(it==nodes_[v].adj.end()) // e is the last element in v's adj list
return nodes_[v].adj.front();
else
return *it;
}
}
void PlanarGraph::clear_faces()
{
// Pop all elements from the graph's list of faces
while(!faces.empty())
{
faces.pop_back();
}
// Set the face indices of all edges to -1
for(std::vector<Edge>::iterator it = edges.begin(); it != edges.end(); ++it)
{
it->left_face = -1;
it->right_face = -1;
}
}
size_t PlanarGraph::compute_dual_num_edges() const
{
// number of dual edges if the number of original edges ( = cross edges ) + clique edges in each face
size_t dual_num_edges = num_edges();
for(size_t f=0; f<faces.size(); ++f) {
const size_t face_size = faces[f].edges.size();
dual_num_edges += (face_size * (face_size - 1))/2;
}
return dual_num_edges;
}
// Planarizes the graph, i.e.
// - Sorts the adjacency lists of all nodes_ to form a rotation system
// - Constructs faces and sets face/edge relations (see definitions of
// struct Edge and struct Face)
void PlanarGraph::planarize()
{
// ToDo
// Assert that the graph is biconnected
// Reserve space for faces (how much?)
//// Copy graph in planarity code graph data structure.
graphP g = gp_New();
gp_InitGraph(g, num_nodes());
for(std::vector<Edge>::iterator it=edges.begin(); it!=edges.end(); ++it)
{
gp_AddEdge(g, it->tail, 0, it->head, 0);
}
// Invoke code that sorts the adjacency lists
if (gp_Embed(g, EMBEDFLAGS_PLANAR) == OK) {
gp_SortVertices(g);
} else {
throw("PlanarGraph not planar\n");
}
//// Repopulate edges in the embedding order
for (size_t i = 0; i < g->N; ++i)
{
size_t u = i;
size_t j = g->G[i].link[1];
while (j >= g->N)
{
OPENGM_ASSERT(i != g->G[j].v); // What does this OPENGM_ASSERT do?
OPENGM_ASSERT(g->G[j].v < g->N);
size_t v = g->G[j].v;
// Find the edge connecting u and v
std::list<size_t>::iterator it = nodes_[u].adj.begin();
while(edges[*it].tail != v && edges[*it].head != v && it != nodes_[u].adj.end())
++it;
size_t e = *it;
OPENGM_ASSERT(it != nodes_[i].adj.end());
// Remove the edge from its current position, and insert at the back
nodes_[u].adj.erase(it);
nodes_[u].adj.push_back(e);
j = g->G[j].link[1];
}
}
//// Clear faces
clear_faces();
//// Construct faces
// do zrobienia: code for following the orbit starting from left and right face is mostly duplication: clean up!
for(size_t e = 0; e < edges.size(); ++e) // Loop over all edges
{
// Check if the right face of e has already been dealt with.
// If not, construct it!
//enum class face_type {left,right};
typedef int face_type;
const face_type face_type_left = 1;
const face_type face_type_right = 2;
if(edges[e].right_face == -1)
{
// Create new face object
const size_t f = faces.size();
faces.resize(f+1);
// Assign e <-> f
faces[f].edges.push_back(e);
edges[e].right_face = f;
// Follow the orbit in FORWARD direction (i.e. starting with e's head)
size_t v = edges[e].head; // Next node
size_t ee = e;
//size_t ee = get_following_edge(v, e); // Next edge
face_type ee_face;
do {
// Get next node and edge
ee = get_following_edge(v, ee);
v = get_dest(v, ee);
// Set f as face of ee, left or right depends on the formal direction of ee
if(v==edges[ee].tail) {
edges[ee].left_face = f;
ee_face = face_type_left;
}
if(v==edges[ee].head) {
edges[ee].right_face = f;
ee_face = face_type_right;
}
faces[f].edges.push_back(ee); // a face can have the same edge in the left and right. do zeobienia: this must be reflected in the faces data structure as well.
} while(! (ee == e && ee_face == face_type_right) ); // If ee==e and we are on the same side again, we went the full circle
}
// Check if the left face of e has already been dealt with.
// If not, construct it!
// to do: remove duplicate code by switching left for right and vice versa
if(edges[e].left_face == -1)
{
// Create new face object
const size_t f = faces.size();
faces.resize(f+1);
// Assign e <-> f
faces[f].edges.push_back(e);
edges[e].left_face = f;
// Follow the orbit in BACKWARD direction (i.e. starting with e's tail)
size_t v = edges[e].tail; // Next node
size_t ee = e;
//size_t ee = get_following_edge(v, e); // Next edge
face_type ee_face;
do {
// Get next node and edge
ee = get_following_edge(v, ee);
v = get_dest(v, ee);
// Set f as face of ee, left or right depends on the formal direction of ee
if(v==edges[ee].tail) {
edges[ee].left_face = f;
ee_face = face_type_left;
}
if(v==edges[ee].head) {
edges[ee].right_face = f;
ee_face = face_type_right;
}
faces[f].edges.push_back(ee); // a face can have the same edge in the left and right. do zeobienia: this must be reflected in the faces data structure as well.
} while(! (ee == e && ee_face == face_type_left) ); // If ee==e and we are on the same side again, we went the full circle
}
}
//// Checks and clean-up
// Check: Do all edges have a left and a right face?
for(std::vector<Edge>::iterator it=edges.begin(); it!=edges.end(); ++it)
{
OPENGM_ASSERT((*it).left_face != -1);
OPENGM_ASSERT((*it).right_face != -1);
}
// Check if genus = 0, i.e graph is planar
OPENGM_ASSERT(num_nodes()-num_edges()+num_faces() == 2);
// Delete planarity code graph
gp_Free(&g);
}
//////////////////////////////////////////////////////
// Construction of dual graph
//////////////////////////////////////////////////////
// Constructs the expanded dual of the graph. The primal graph needs to
// be planarized before.
void PlanarGraph::construct_dual()
{
// Allocate dual graph in PerfectMatching data structure
// Todo: Reasonable number of max dual edges
Dual_ = new PerfectMatching(2*num_edges(), compute_dual_num_edges());
// Dual_ = std::unique_ptr<PerfectMatching>(new PerfectMatching(2*num_edges(), compute_dual_num_edges()));
PerfectMatching::Options Dual_options;
Dual_options.verbose = false;
Dual_->options = Dual_options;
// insert all cross edges corresponding to the original edges
// note: cross edges directly correspond to the original edges
size_t counter = 0;
for(size_t e = 0; e < edges.size(); ++e)
{
// For the current edge of G, add dual nodes_ for its two faces
const size_t u = counter;
const size_t v = counter + 1;
counter += 2;
// Add the dual cross edge of e, connecting u and v
// Weight is the negative of e's weight
Dual_->AddEdge(u, v, edges[e].weight);
}
// insert clique edges connecting all dual nodes inside a face
counter = 0;
for(size_t e = 0; e < edges.size(); ++e)
{
size_t u = counter;
size_t v = counter + 1;
counter += 2;
// "Integrate" u into the left face of e
size_t f = edges[e].left_face;
for(std::list<size_t>::iterator it = faces[f].dual_nodes.begin(); it != faces[f].dual_nodes.end(); ++it)
{
Dual_->AddEdge(u, *it, 0.0);
}
faces[f].dual_nodes.push_back(u);
// "Integrate" v into the right face
f = edges[e].right_face;
for(std::list<size_t>::iterator it = faces[f].dual_nodes.begin(); it != faces[f].dual_nodes.end(); ++it)
{
Dual_->AddEdge(v, *it, 0.0);
}
faces[f].dual_nodes.push_back(v);
}
}
double PlanarGraph::cost_of_cut() const
{
double cost = 0.0;
for(size_t e = 0; e < num_edges(); ++e)
{
if(Dual_->GetSolution(e) == 0)
cost += edges[e].weight;
}
return cost;
}
double PlanarGraph::cost_of_cut(const std::vector<int>& x) const
{
// do zrobienia: check if x is a cut
double cost = 0.0;
for(size_t e = 0; e < num_edges(); ++e)
{
if(x[e] == 1)
cost += edges[e].weight;
}
return cost;
}
void PlanarGraph::calculate_maxcut()
{
//OPENGM_ASSERT(Dual_ != nullptr);
OPENGM_ASSERT(Dual_ != NULL);
Dual_->Solve();
}
std::vector<bool> PlanarGraph::get_cut() const
{
std::vector<bool> cut(num_edges(),false);
for(size_t e = 0; e < num_edges(); ++e)
{
if(Dual_->GetSolution(e) == 0) {
cut[e] = true;
} else if(Dual_->GetSolution(e) == 1) {
cut[e] = false;
} else {
throw std::logic_error("Perfect matching solver did not succeed");
}
}
return cut;
}
// Reads the labeling defined by a given cut into the vector x. Does
// not output the labels for the unary nodes_. A cut has to be given
std::vector<int> PlanarGraph::get_labeling_from_cut(const std::vector<bool>& cut) const
{
OPENGM_ASSERT(cut.size() == edges.size());
// Make labeling size num_nodes(), i.e. including unary nodes_. Set all
// labels to -1 (meaning unassigned)
std::vector<int> labeling(num_nodes());
for(size_t v = 0; v < num_nodes(); ++v)
labeling[v] = -1;
std::stack<size_t> s;
size_t visited_nodes=0;
for(size_t startnode=0; startnode< num_nodes(); ++startnode){
if(visited_nodes==num_nodes())
break;
if( labeling[startnode]!= -1)
continue;
labeling[startnode] = 0;
s.push(startnode);
while(!s.empty()) // As long as stack is not empty
{
// Take top element from stack
size_t u = s.top();
s.pop();
++visited_nodes;
// Go through all incident edges
for(std::list<size_t>::const_iterator it = nodes_[u].adj.begin(); it != nodes_[u].adj.end(); ++it)
{
size_t e = *it; // Edge and...
size_t v = get_dest(u, e); // its destination (i.e. the neighbor)
// If the neighbor has not yet been seen, put it on the
// stack and assign the respective label
if(labeling[v] == -1)
{
s.push(v);
if(cut[e])
labeling[v] = (labeling[u] + 1) % 2; // mapping 0->1 and 1->0
else
labeling[v] = labeling[u];
}
// Check for inconsistent cut when encountering a node again
if(labeling[v] != -1) // node already seen
{
if(cut[e]) {
OPENGM_ASSERT(labeling[v] + labeling[u] == 1);
} else {
OPENGM_ASSERT(labeling[v] == labeling[u]);
}
}
}
}
}
for(size_t v=0; v<labeling.size(); ++v) {
OPENGM_ASSERT(labeling[v] == 0 || labeling[v] == 1);
}
return labeling;
}
void PlanarGraph::get_labeling(std::vector<int> & x) const
{
std::vector<bool> cut = get_cut();
x = get_labeling_from_cut(cut);
}
} //namespace planargraph
} // namespace external
} // namespace opengm
#endif // OPENGM_PLANAR_GRAPH_HXX
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