X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;ds=inline;f=mtp_graph.cc;h=052de17884763a1a32747e149b0f047e3ee23f20;hb=c7d5cdf1982dacc5451f79599041b2e95524d3f7;hp=4608b82f428fe252c96aec1fbf6656f753f3238b;hpb=6afe91234d7807ce82b96a071087decb2f7aead3;p=mtp.git
diff --git a/mtp_graph.cc b/mtp_graph.cc
index 4608b82..052de17 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -1,20 +1,26 @@
-///////////////////////////////////////////////////////////////////////////
-// 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"
@@ -43,9 +49,11 @@ public:
scalar_t distance_from_source;
Edge *pred_edge_toward_source;
- int iteration; // Used in find_shortest_path to know if we already
- // added this vertex to the front
+ int last_change; // Used to mark which edges have already been
+ // processed in some methods
+
Vertex();
+
inline void add_leaving_edge(Edge *e);
inline void del_leaving_edge(Edge *e);
};
@@ -54,7 +62,7 @@ public:
void Edge::invert() {
length = - length;
- positivized_length = 0;
+ positivized_length = - positivized_length;
origin_vertex->del_leaving_edge(this);
terminal_vertex->add_leaving_edge(this);
Vertex *t = terminal_vertex;
@@ -90,7 +98,7 @@ void Vertex::del_leaving_edge(Edge *e) {
//////////////////////////////////////////////////////////////////////
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;
@@ -103,16 +111,16 @@ MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
_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_leaving_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;
@@ -147,22 +155,22 @@ void MTPGraph::print(ostream *os) {
void MTPGraph::print_dot(ostream *os) {
(*os) << "digraph {" << endl;
- // (*os) << " node [shape=circle];" << endl;
- (*os) << " edge [color=gray]" << endl;
+ (*os) << " rankdir=\"LR\";" << 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;
+ // << ";"
+ // << endl;
+ (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ << " [";
if(e->occupied) {
- (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
- << " [style=bold,color=black,label=\"" << e->length << "\"];" << endl;
- } else {
- (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
- << " [label=\"" << e->length << "\"];" << endl;
+ (*os) << "style=bold,color=black,";
}
+ (*os) << "label=\"" << e->length << "\"];" << endl;
}
(*os) << "}" << endl;
}
@@ -198,32 +206,83 @@ void MTPGraph::force_positivized_lengths() {
#endif
}
-// This method does not change the edge occupation. It update
-// distance_from_source and pred_edge_toward_source.
+int MTPGraph::is_dag() {
+ Vertex *v;
+ Edge *e;
+
+ // We put everybody in the front
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].last_change = -1;
+ _front[k] = &_vertices[k];
+ }
+
+ int iteration = 0;
+ int front_size = _nb_vertices, pred_front_size;
+
+ do {
+ // 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) {
+ e->terminal_vertex->last_change = iteration;
+ }
+ }
+
+ pred_front_size = front_size;
+ front_size = 0;
+
+ // We remove all the vertices without incoming edge
+ for(int f = 0; f < pred_front_size; f++) {
+ v = _front[f];
+ if(v->last_change == iteration) {
+ _front[front_size++] = v;
+ }
+ }
+
+ iteration++;
+ } while(front_size < pred_front_size);
+
+ return front_size == 0;
+}
+
+// This method does not change the edge occupation. It only set
+// properly for every vertex the fields 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 v = 0; v < _nb_vertices; v++) {
- _vertices[v].distance_from_source = FLT_MAX;
- _vertices[v].pred_edge_toward_source = 0;
- _vertices[v].iteration = 0;
+#ifdef DEBUG
+ if(is_dag()) {
+ cout << "find_shortest_path: DAG -> ok" << endl;
+ } else {
+ for(int e = 0; e < _nb_edges; e++) {
+ if(_edges[e].positivized_length < 0) abort();
+ }
+ cout << "find_shortest_path: All positivized_length are positive -> ok" << endl;
+ }
+#endif
+
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].distance_from_source = FLT_MAX;
+ _vertices[k].pred_edge_toward_source = 0;
+ _vertices[k].last_change = -1;
}
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;
- iteration++;
+ new_front_size = 0;
- for(int f = 0; f < _front_size; f++) {
+ for(int f = 0; f < front_size; f++) {
v = _front[f];
for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
d = v->distance_from_source + e->positivized_length;
@@ -231,22 +290,20 @@ void MTPGraph::find_shortest_path() {
if(d < tv->distance_from_source) {
tv->distance_from_source = d;
tv->pred_edge_toward_source = e;
- if(tv->iteration < iteration) {
- _new_front[_new_front_size++] = tv;
- tv->iteration = iteration;
+ if(tv->last_change < iteration) {
+ _new_front[new_front_size++] = tv;
+ tv->last_change = iteration;
}
}
}
}
- tmp_front = _new_front;
- _new_front = _front;
- _front = tmp_front;
+ tmp_front = _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);
+ front_size = new_front_size;
+
+ iteration++;
+ } while(front_size > 0);
}
void MTPGraph::find_best_paths(scalar_t *lengths) {
@@ -260,8 +317,9 @@ void MTPGraph::find_best_paths(scalar_t *lengths) {
_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.
+ // We call find_shortest_path here to set properly the distances to
+ // the source, so that we can make all the edge lengths positive at
+ // the first iteration.
find_shortest_path();
do {
@@ -271,9 +329,10 @@ void MTPGraph::find_best_paths(scalar_t *lengths) {
total_length = 0.0;
- // Do we reach the _sink?
+ // Do we reach the sink?
if(_sink->pred_edge_toward_source) {
- // If yes, compute the length of the best path
+ // If yes, compute the length of the best path according to the
+ // original edge lengths
v = _sink;
while(v->pred_edge_toward_source) {
total_length += v->pred_edge_toward_source->length;