X-Git-Url: https://www.fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=95dc4510af14e4cd8888e943209c8f808235d7dd;hb=79a4a9ab164a667ecb551078e1cd773e2140e3c2;hp=ee6da31de61df9abe9705b41a895763b612ccd00;hpb=8df7c7e77366cb95e9e8e963af9319d9cbac1934;p=mtp.git

diff --git a/mtp_graph.cc b/mtp_graph.cc
index ee6da31..95dc451 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -26,22 +26,24 @@ using namespace std;
 class Edge {
 public:
   int id, occupied;
-  scalar_t length, work_length;
+  scalar_t length, positivized_length;
   Vertex *origin_vertex, *terminal_vertex;
 
   // These are the links in the origin_vertex leaving edge list
-  Edge *next, *pred;
+  Edge *next_leaving_edge, *pred_leaving_edge;
 
   inline void revert();
 };
 
 class Vertex {
 public:
-  int id, iteration;
-  Edge *root_edge;
+  int id;
+  Edge *leaving_edges;
   scalar_t distance_from_source;
   Edge *best_pred_edge_to_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);
@@ -51,7 +53,7 @@ public:
 
 void Edge::revert() {
   length = - length;
-  work_length = 0;
+  positivized_length = 0;
   origin_vertex->del_edge(this);
   terminal_vertex->add_edge(this);
   Vertex *t = terminal_vertex;
@@ -62,20 +64,20 @@ void Edge::revert() {
 //////////////////////////////////////////////////////////////////////
 
 Vertex::Vertex() {
-  root_edge = 0;
+  leaving_edges = 0;
 }
 
 void Vertex::add_edge(Edge *e) {
-  e->next = root_edge;
-  e->pred = 0;
-  if(root_edge) { root_edge->pred = e; }
-  root_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 == root_edge) { root_edge = e->next; }
-  if(e->pred) { e->pred->next = e->next; }
-  if(e->next) { e->next->pred = e->pred; }
+  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; }
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -146,38 +148,38 @@ MTPGraph::~MTPGraph() {
   delete[] _new_front;
 }
 
-void MTPGraph::initialize_work_lengths_with_min() {
+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].root_edge; e; e = e->next) {
+    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].root_edge; e; e = e->next) {
-      e->work_length = e->length - length_min;
+    for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
+      e->positivized_length = e->length - length_min;
     }
   }
 }
 
-void MTPGraph::update_work_lengths() {
+void MTPGraph::update_positivized_lengths() {
   for(int k = 0; k < _nb_edges; k++) {
     Edge *e = _edges + k;
-    e->work_length += e->terminal_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
+    e->positivized_length += e->terminal_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
   }
 }
 
-void MTPGraph::force_positive_work_lengths() {
+void MTPGraph::force_positivized_lengths() {
 #ifdef VERBOSE
   scalar_t residual_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;
 #endif
-        e->work_length = 0.0;
+        e->positivized_length = 0.0;
       }
     }
   }
@@ -192,6 +194,7 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
   Vertex **tmp_front;
   int tmp_front_size;
   Vertex *v, *tv;
+  Edge *e;
   scalar_t d;
 
   for(int v = 0; v < _nb_vertices; v++) {
@@ -211,8 +214,8 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
     iteration++;
     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;
@@ -242,21 +245,21 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
 
   for(int e = 0; e < _nb_edges; e++) {
     _edges[e].length = lengths[e];
-    _edges[e].work_length = _edges[e].length;
+    _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_work_lengths();
+  update_positivized_lengths();
 
   // #warning
-  // initialize_work_lengths_with_min();
+  // initialize_positivized_lengths_with_min();
 
   do {
-    force_positive_work_lengths();
+    force_positivized_lengths();
     find_shortest_path(_front, _new_front);
-    update_work_lengths();
+    update_positivized_lengths();
 
     total_length = 0.0;
 
@@ -279,6 +282,8 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
           e = v->best_pred_edge_to_source;
           v = e->origin_vertex;
           e->revert();
+          // This is the only place where we change the occupations of
+          // edges
           e->occupied = 1 - e->occupied;
         }
       }