-///////////////////////////////////////////////////////////////////////////
-// This program is free software: you can redistribute it and/or modify //
-// it under the terms of the version 3 of the GNU General Public License //
-// as published by the Free Software Foundation. //
-// //
-// This program is distributed in the hope that it will be useful, but //
-// WITHOUT ANY WARRANTY; without even the implied warranty of //
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU //
-// General Public License for more details. //
-// //
-// You should have received a copy of the GNU General Public License //
-// along with this program. If not, see <http://www.gnu.org/licenses/>. //
-// //
-// Written by and Copyright (C) Francois Fleuret //
-// Contact <francois.fleuret@idiap.ch> for comments & bug reports //
-///////////////////////////////////////////////////////////////////////////
+/*
+ * mtp is the ``Multi Tracked Path'', an implementation of the
+ * k-shortest path algorithm for multi-target tracking.
+ *
+ * Copyright (c) 2012 Idiap Research Institute, http://www.idiap.ch/
+ * Written by Francois Fleuret <francois.fleuret@idiap.ch>
+ *
+ * This file is part of mtp.
+ *
+ * mtp is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * mtp is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with selector. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
#include "mtp_graph.h"
#include <iostream>
#include <float.h>
+#include <stdlib.h>
using namespace std;
// These are the links in the origin_vertex leaving edge list
Edge *next_leaving_edge, *pred_leaving_edge;
- inline void revert();
+ inline void invert();
};
class Vertex {
int id;
Edge *leaving_edges;
scalar_t distance_from_source;
- Edge *best_pred_edge_to_source;
+ Edge *pred_edge_toward_source;
int iteration; // Used in find_shortest_path to know if we already
// added this vertex to the front
Vertex();
- inline void add_edge(Edge *e);
- inline void del_edge(Edge *e);
+ inline void add_leaving_edge(Edge *e);
+ inline void del_leaving_edge(Edge *e);
};
//////////////////////////////////////////////////////////////////////
-void Edge::revert() {
+void Edge::invert() {
length = - length;
positivized_length = 0;
- origin_vertex->del_edge(this);
- terminal_vertex->add_edge(this);
+ origin_vertex->del_leaving_edge(this);
+ terminal_vertex->add_leaving_edge(this);
Vertex *t = terminal_vertex;
terminal_vertex = origin_vertex;
origin_vertex = t;
leaving_edges = 0;
}
-void Vertex::add_edge(Edge *e) {
+void Vertex::add_leaving_edge(Edge *e) {
e->next_leaving_edge = leaving_edges;
e->pred_leaving_edge = 0;
if(leaving_edges) { leaving_edges->pred_leaving_edge = e; }
leaving_edges = e;
}
-void Vertex::del_edge(Edge *e) {
- if(e == leaving_edges) { leaving_edges = e->next_leaving_edge; }
- if(e->pred_leaving_edge) { e->pred_leaving_edge->next_leaving_edge = e->next_leaving_edge; }
- if(e->next_leaving_edge) { e->next_leaving_edge->pred_leaving_edge = e->pred_leaving_edge; }
+void Vertex::del_leaving_edge(Edge *e) {
+ if(e == leaving_edges) {
+ leaving_edges = e->next_leaving_edge;
+ }
+ if(e->pred_leaving_edge) {
+ e->pred_leaving_edge->next_leaving_edge = e->next_leaving_edge;
+ }
+ if(e->next_leaving_edge) {
+ e->next_leaving_edge->pred_leaving_edge = e->pred_leaving_edge;
+ }
}
//////////////////////////////////////////////////////////////////////
MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
- int *from, int *to,
+ int *vertex_from, int *vertex_to,
int source, int sink) {
_nb_vertices = nb_vertices;
_nb_edges = nb_edges;
}
for(int e = 0; e < nb_edges; e++) {
- _vertices[from[e]].add_edge(_edges + e);
+ _vertices[vertex_from[e]].add_leaving_edge(_edges + e);
_edges[e].occupied = 0;
_edges[e].id = e;
- _edges[e].origin_vertex = _vertices + from[e];
- _edges[e].terminal_vertex = _vertices + to[e];
+ _edges[e].origin_vertex = _vertices + vertex_from[e];
+ _edges[e].terminal_vertex = _vertices + vertex_to[e];
}
paths = 0;
//////////////////////////////////////////////////////////////////////
-void MTPGraph::print() {
+void MTPGraph::print(ostream *os) {
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
- cout << e->origin_vertex->id
+ (*os) << e->origin_vertex->id
<< " -> "
<< e->terminal_vertex->id
<< " "
<< e->length;
if(e->occupied) {
- cout << " *";
+ (*os) << " *";
}
- cout << endl;
+ (*os) << endl;
}
}
-void MTPGraph::print_dot() {
- cout << "digraph {" << endl;
- cout << " node[shape=circle];" << endl;
+void MTPGraph::print_dot(ostream *os) {
+ (*os) << "digraph {" << endl;
+ (*os) << " node [shape=circle,width=0.75,fixedsize=true];" << endl;
+ (*os) << " edge [color=gray,arrowhead=open]" << endl;
+ (*os) << " " << _source->id << " [peripheries=2];" << endl;
+ (*os) << " " << _sink->id << " [peripheries=2];" << endl;
+ // (*os) << " " << _source->id << " [style=bold,color=red];" << endl;
+ // (*os) << " " << _sink->id << " [style=bold,color=green];" << endl;
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
+ // (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ // << ";"
+ // << endl;
+ (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ << " [";
if(e->occupied) {
- cout << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
- << " [style=bold,color=black,label=\"" << -e->length << "\"];" << endl;
- } else {
- cout << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
- << " [color=gray,label=\"" << e->length << "\"];" << endl;
+ (*os) << "style=bold,color=black,";
}
+ (*os) << "label=\"" << e->length << "\"];" << endl;
}
- cout << "}" << endl;
+ (*os) << "}" << endl;
}
//////////////////////////////////////////////////////////////////////
-void MTPGraph::initialize_positivized_lengths_with_min() {
- scalar_t length_min = 0;
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
- length_min = min(e->length, length_min);
- }
- }
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
- e->positivized_length = e->length - length_min;
- }
- }
-}
-
void MTPGraph::update_positivized_lengths() {
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
- e->positivized_length += e->terminal_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
+ e->positivized_length +=
+ e->origin_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
}
}
void MTPGraph::force_positivized_lengths() {
#ifdef VERBOSE
scalar_t residual_error = 0.0;
+ scalar_t max_error = 0.0;
#endif
for(int n = 0; n < _nb_vertices; n++) {
for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
if(e->positivized_length < 0) {
#ifdef VERBOSE
residual_error -= e->positivized_length;
+ max_error = max(max_error, - e->positivized_length);
#endif
e->positivized_length = 0.0;
}
}
}
#ifdef VERBOSE
- cerr << "residual_error " << residual_error << endl;
+ cerr << "residual_error " << residual_error << " max_error " << residual_error << endl;
#endif
}
// This method does not change the edge occupation. It update
-// distance_from_source and best_pred_edge_to_source.
-void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
+// distance_from_source and pred_edge_toward_source.
+void MTPGraph::find_shortest_path() {
Vertex **tmp_front;
int tmp_front_size;
Vertex *v, *tv;
for(int v = 0; v < _nb_vertices; v++) {
_vertices[v].distance_from_source = FLT_MAX;
- _vertices[v].best_pred_edge_to_source = 0;
+ _vertices[v].pred_edge_toward_source = 0;
_vertices[v].iteration = 0;
}
do {
_new_front_size = 0;
iteration++;
+
for(int f = 0; f < _front_size; f++) {
v = _front[f];
for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
tv = e->terminal_vertex;
if(d < tv->distance_from_source) {
tv->distance_from_source = d;
- tv->best_pred_edge_to_source = e;
+ tv->pred_edge_toward_source = e;
if(tv->iteration < iteration) {
_new_front[_new_front_size++] = tv;
tv->iteration = iteration;
} while(_front_size > 0);
}
-void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
+void MTPGraph::find_best_paths(scalar_t *lengths) {
scalar_t total_length;
Vertex *v;
Edge *e;
for(int e = 0; e < _nb_edges; e++) {
_edges[e].length = lengths[e];
+ _edges[e].occupied = 0;
_edges[e].positivized_length = _edges[e].length;
}
// We use one iteration of find_shortest_path simply to propagate
// the distance to make all the edge lengths positive.
- find_shortest_path(_front, _new_front);
- update_positivized_lengths();
-
- // #warning
- // initialize_positivized_lengths_with_min();
+ find_shortest_path();
do {
- force_positivized_lengths();
- find_shortest_path(_front, _new_front);
update_positivized_lengths();
+ force_positivized_lengths();
+ find_shortest_path();
total_length = 0.0;
// Do we reach the _sink?
- if(_sink->best_pred_edge_to_source) {
+ if(_sink->pred_edge_toward_source) {
// If yes, compute the length of the best path
v = _sink;
- while(v->best_pred_edge_to_source) {
- total_length += v->best_pred_edge_to_source->length;
- v = v->best_pred_edge_to_source->origin_vertex;
+ while(v->pred_edge_toward_source) {
+ total_length += v->pred_edge_toward_source->length;
+ v = v->pred_edge_toward_source->origin_vertex;
}
// If that length is negative
if(total_length < 0.0) {
#ifdef VERBOSE
- cout << "Found a path of length " << total_length << endl;
+ cerr << "Found a path of length " << total_length << endl;
#endif
// Invert all the edges along the best path
v = _sink;
- while(v->best_pred_edge_to_source) {
- e = v->best_pred_edge_to_source;
+ while(v->pred_edge_toward_source) {
+ e = v->pred_edge_toward_source;
v = e->origin_vertex;
- e->revert();
+ e->invert();
// This is the only place where we change the occupations of
// edges
e->occupied = 1 - e->occupied;
} while(total_length < 0.0);
+ // Put back the graph in its original state (i.e. invert edges which
+ // have been inverted in the process)
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
- if(e->occupied) { e->revert(); }
- result_edge_occupation[k] = e->occupied;
+ if(e->occupied) { e->invert(); }
}
}
-void MTPGraph::retrieve_paths() {
+int MTPGraph::retrieve_one_path(Edge *e, Path *path) {
+ Edge *f, *next = 0;
+ int l = 0;
+
+ if(path) {
+ path->nodes[l++] = e->origin_vertex->id;
+ path->length = e->length;
+ } else l++;
+
+ while(e->terminal_vertex != _sink) {
+ if(path) {
+ path->nodes[l++] = e->terminal_vertex->id;
+ path->length += e->length;
+ } else l++;
+ int nb_choices = 0;
+ for(f = e->terminal_vertex->leaving_edges; f; f = f->next_leaving_edge) {
+ if(f->occupied) { nb_choices++; next = f; }
+ if(nb_choices == 0) {
+ cerr << "retrieve_one_path: Non-sink end point." << endl;
+ abort();
+ }
+ if(nb_choices > 1) {
+ cerr << "retrieve_one_path: Non node-disjoint paths." << endl;
+ abort();
+ }
+ }
+ e = next;
+ }
+
+ if(path) {
+ path->nodes[l++] = e->terminal_vertex->id;
+ path->length += e->length;
+ } else l++;
+
+ return l;
+}
+
+void MTPGraph::retrieve_disjoint_paths() {
Edge *e;
for(int p = 0; p < nb_paths; p++) delete paths[p];
int p = 0;
for(e = _source->leaving_edges; e; e = e->next_leaving_edge) {
if(e->occupied) {
- paths[p] = new Path();
+ int l = retrieve_one_path(e, 0);
+ paths[p] = new Path(l);
+ retrieve_one_path(e, paths[p]);
p++;
}
}
-
- cout << "NB_PATHS " << nb_paths << endl;
}