X-Git-Url: https://www.fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=9a811bba9ae5095b625cd7589c0bfdd024d2c298;hb=34022d5e987cf13ff6db31a6d7263e9266a8b1c0;hp=c7e6b986eacf0298c8f89da985156d94dbb97d43;hpb=468580db238e44d27dcc91f6313511bf9a054c81;p=mtp.git
diff --git a/mtp_graph.cc b/mtp_graph.cc
index c7e6b98..9a811bb 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -1,196 +1,287 @@
-///////////////////////////////////////////////////////////////////////////
-// 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 . //
-// //
-// Written by and Copyright (C) Francois Fleuret //
-// Contact for comments & bug reports //
-///////////////////////////////////////////////////////////////////////////
+/*
+ * mtp is the ``Multi Tracked Paths'', an implementation of the
+ * k-shortest paths algorithm for multi-target tracking.
+ *
+ * Copyright (c) 2012 Idiap Research Institute, http://www.idiap.ch/
+ * Written by Francois Fleuret
+ *
+ * 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 .
+ *
+ */
#include "mtp_graph.h"
#include
#include
+#include
using namespace std;
class Edge {
public:
int id, occupied;
- scalar_t length, work_length;
- Vertex *terminal_vertex;
- Edge *next, *pred;
+ scalar_t length, positivized_length;
+ Vertex *origin_vertex, *terminal_vertex;
+
+ // These are the links in the origin_vertex leaving edge list
+ Edge *next_leaving_edge, *pred_leaving_edge;
+
+ inline void invert();
};
class Vertex {
public:
- int id, iteration;
- Edge *root_edge;
+ int id;
+ Edge *leaving_edges;
scalar_t distance_from_source;
- Vertex *pred_vertex;
- Edge *pred_edge;
+ Edge *pred_edge_toward_source;
- Vertex() { root_edge = 0; }
+ int iteration; // Used in find_shortest_path to know if we already
+ // added this vertex to the front
+ Vertex();
+ inline void add_leaving_edge(Edge *e);
+ inline void del_leaving_edge(Edge *e);
+};
- inline void add_edge(Edge *e) {
- e->next = root_edge;
- e->pred = 0;
- if(root_edge) { root_edge->pred = e; }
- root_edge = e;
- }
+//////////////////////////////////////////////////////////////////////
- inline void del_edge(Edge *e) {
- if(e == root_edge) { root_edge = e->next; }
- if(e->pred) { e->pred->next = e->next; }
- if(e->next) { e->next->pred = e->pred; }
- }
-};
+void Edge::invert() {
+ length = - length;
+ positivized_length = 0;
+ origin_vertex->del_leaving_edge(this);
+ terminal_vertex->add_leaving_edge(this);
+ Vertex *t = terminal_vertex;
+ terminal_vertex = origin_vertex;
+ origin_vertex = t;
+}
-void MTPGraph::print() {
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- cout << n << " -> " << e->terminal_vertex->id << " " << e->length;
- if(e->occupied) {
- cout << " *";
- }
- cout << endl;
- }
- }
+//////////////////////////////////////////////////////////////////////
+
+Vertex::Vertex() {
+ leaving_edges = 0;
}
-void MTPGraph::print_dot() {
- cout << "digraph {" << endl;
- cout << " node[shape=circle];" << endl;
- for(int n = 0; n < _nb_vertices; n++) {
- int a = vertices[n].id;
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- int b = e->terminal_vertex->id;
- if(e->occupied) {
- cout << " " << b << " -> " << a << " [style=bold,color=black,label=\"" << -e->length << "\"];" << endl;
- } else {
- cout << " " << a << " -> " << b << " [color=gray,label=\"" << e->length << "\"];" << endl;
- }
- }
+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_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;
}
- cout << "}" << endl;
}
+//////////////////////////////////////////////////////////////////////
+
MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
- int *from, int *to,
- int src, int snk) {
+ int *vertex_from, int *vertex_to,
+ int source, int sink) {
_nb_vertices = nb_vertices;
_nb_edges = nb_edges;
- edges = new Edge[_nb_edges];
- vertices = new Vertex[_nb_vertices];
+ _edges = new Edge[_nb_edges];
+ _vertices = new Vertex[_nb_vertices];
_front = new Vertex *[_nb_vertices];
_new_front = new Vertex *[_nb_vertices];
- _source = &vertices[src];
- _sink = &vertices[snk];
+ _source = &_vertices[source];
+ _sink = &_vertices[sink];
- for(int v = 0; v < _nb_vertices; v++) {
- vertices[v].id = v;
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].id = k;
}
for(int e = 0; e < nb_edges; e++) {
- vertices[from[e]].add_edge(&edges[e]);
- edges[e].occupied = 0;
- edges[e].id = e;
- edges[e].terminal_vertex = &vertices[to[e]];
+ _vertices[vertex_from[e]].add_leaving_edge(_edges + e);
+ _edges[e].occupied = 0;
+ _edges[e].id = e;
+ _edges[e].origin_vertex = _vertices + vertex_from[e];
+ _edges[e].terminal_vertex = _vertices + vertex_to[e];
}
+ paths = 0;
+ nb_paths = 0;
}
MTPGraph::~MTPGraph() {
- delete[] vertices;
- delete[] edges;
+ delete[] _vertices;
+ delete[] _edges;
delete[] _front;
delete[] _new_front;
+ for(int p = 0; p < nb_paths; p++) delete paths[p];
+ delete[] paths;
}
-void MTPGraph::initialize_work_lengths() {
- scalar_t length_min = 0;
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- length_min = min(e->length, length_min);
- }
- }
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- e->work_length = e->length - length_min;
+//////////////////////////////////////////////////////////////////////
+
+void MTPGraph::print(ostream *os) {
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ (*os) << e->origin_vertex->id
+ << " -> "
+ << e->terminal_vertex->id
+ << " "
+ << e->length;
+ if(e->occupied) {
+ (*os) << " *";
}
+ (*os) << endl;
}
}
-void MTPGraph::update_work_lengths() {
- for(int n = 0; n < _nb_vertices; n++) {
- scalar_t d = vertices[n].distance_from_source;
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- e->work_length += d - e->terminal_vertex->distance_from_source;
+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;
+ 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) {
+ (*os) << "style=bold,color=black,";
}
+ (*os) << "label=\"" << e->length << "\"];" << endl;
}
+ (*os) << "}" << endl;
}
-void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
- Vertex **tmp_front;
- int tmp_front_size;
- Vertex *v, *tv;
- scalar_t d;
+//////////////////////////////////////////////////////////////////////
+
+void MTPGraph::update_positivized_lengths() {
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ 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].root_edge; e; e = e->next) {
- if(e->work_length < 0) {
+ for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
+ if(e->positivized_length < 0) {
#ifdef VERBOSE
- residual_error -= e->work_length;
+ residual_error -= e->positivized_length;
+ max_error = max(max_error, - e->positivized_length);
#endif
- e->work_length = 0.0;
+ e->positivized_length = 0.0;
}
}
}
#ifdef VERBOSE
- cerr << "residual_error " << residual_error << endl;
+ cerr << "residual_error " << residual_error << " max_error " << residual_error << endl;
#endif
+}
+
+int MTPGraph::is_dag() {
+ Vertex *v, *tv;
+ Edge *e;
+
+ // We put everybody in the front
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].iteration = 0;
+ _front[k] = &_vertices[k];
+ }
+
+ int front_size = _nb_vertices, nb_with_incoming;
+ int iteration = 0;
+ int new_front_size, pred_front_size;
+
+ do {
+ iteration++;
+ nb_with_incoming = 0;
- for(int v = 0; v < _nb_vertices; v++) {
- vertices[v].distance_from_source = FLT_MAX;
- vertices[v].pred_vertex = 0;
- vertices[v].pred_edge = 0;
- vertices[v].iteration = 0;
+ // We set the iteration field of all vertex with incoming edges to
+ // the current iteration value
+ 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;
+ tv->iteration = iteration;
+ }
+ }
+
+ new_front_size = 0;
+ // We remove all vertex without incoming edge
+ for(int f = 0; f < front_size; f++) {
+ v = _front[f];
+ if(v->iteration == iteration) {
+ _front[new_front_size++] = v;
+ }
+ }
+
+ pred_front_size = front_size;
+ front_size = new_front_size;
+ } while(front_size < pred_front_size);
+
+ return front_size == 0;
+}
+
+// This method does not change the edge occupation. It update
+// distance_from_source and pred_edge_toward_source.
+void MTPGraph::find_shortest_path() {
+ Vertex **tmp_front;
+ int tmp_front_size;
+ Vertex *v, *tv;
+ Edge *e;
+ scalar_t d;
+
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].distance_from_source = FLT_MAX;
+ _vertices[k].pred_edge_toward_source = 0;
+ _vertices[k].iteration = 0;
}
int iteration = 0;
- int _front_size = 0, _new_front_size;
- _front[_front_size++] = _source;
+ int front_size = 0, new_front_size;
+ _front[front_size++] = _source;
_source->distance_from_source = 0;
do {
- _new_front_size = 0;
+ new_front_size = 0;
iteration++;
- for(int f = 0; f < _front_size; f++) {
+
+ for(int f = 0; f < front_size; f++) {
v = _front[f];
- for(Edge *e = v->root_edge; e; e = e->next) {
- d = v->distance_from_source + e->work_length;
+ for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
+ d = v->distance_from_source + e->positivized_length;
tv = e->terminal_vertex;
if(d < tv->distance_from_source) {
tv->distance_from_source = d;
- tv->pred_vertex = v;
- tv->pred_edge = e;
+ tv->pred_edge_toward_source = e;
if(tv->iteration < iteration) {
- _new_front[_new_front_size++] = tv;
+ _new_front[new_front_size++] = tv;
tv->iteration = iteration;
}
}
@@ -201,54 +292,130 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
_new_front = _front;
_front = tmp_front;
- tmp_front_size = _new_front_size;
- _new_front_size = _front_size;
- _front_size = tmp_front_size;
- } while(_front_size > 0);
+ tmp_front_size = new_front_size;
+ new_front_size = front_size;
+ front_size = tmp_front_size;
+ } 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].length = lengths[e];
+ _edges[e].occupied = 0;
+ _edges[e].positivized_length = _edges[e].length;
}
- initialize_work_lengths();
+ // Let's be a bit paranoid
+ ASSERT(is_dag());
+
+ // We use one iteration of find_shortest_path simply to propagate
+ // the distance to make all the edge lengths positive.
+ find_shortest_path();
do {
+ update_positivized_lengths();
+ force_positivized_lengths();
+ find_shortest_path();
+
total_length = 0.0;
- find_shortest_path(_front, _new_front);
- update_work_lengths();
// Do we reach the _sink?
- if(_sink->pred_edge) {
-
+ if(_sink->pred_edge_toward_source) {
// If yes, compute the length of the best path
- for(Vertex *v = _sink; v->pred_edge; v = v->pred_vertex) {
- total_length += v->pred_edge->length;
+ v = _sink;
+ 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
+ cerr << "Found a path of length " << total_length << endl;
+#endif
// Invert all the edges along the best path
- for(Vertex *v = _sink; v->pred_edge; v = v->pred_vertex) {
- Edge *e = v->pred_edge;
- e->terminal_vertex = v->pred_vertex;
+ v = _sink;
+ while(v->pred_edge_toward_source) {
+ e = v->pred_edge_toward_source;
+ v = e->origin_vertex;
+ e->invert();
+ // This is the only place where we change the occupations of
+ // edges
e->occupied = 1 - e->occupied;
- e->length = - e->length;
- e->work_length = - e->work_length;
- v->pred_vertex->del_edge(e);
- v->add_edge(e);
}
}
}
+
} while(total_length < 0.0);
- for(int n = 0; n < _nb_vertices; n++) {
- Vertex *v = &vertices[n];
- for(Edge *e = v->root_edge; e; e = e->next) {
- result_edge_occupation[e->id] = e->occupied;
+ // 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->invert(); }
+ }
+}
+
+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];
+ delete[] paths;
+
+ nb_paths = 0;
+ for(e = _source->leaving_edges; e; e = e->next_leaving_edge) {
+ if(e->occupied) { nb_paths++; }
+ }
+
+ paths = new Path *[nb_paths];
+
+ int p = 0;
+ for(e = _source->leaving_edges; e; e = e->next_leaving_edge) {
+ if(e->occupied) {
+ int l = retrieve_one_path(e, 0);
+ paths[p] = new Path(l);
+ retrieve_one_path(e, paths[p]);
+ p++;
}
}
}