From 9d6402aad470e5603b1a6be8a3202710ae1483dd Mon Sep 17 00:00:00 2001
From: DennisOSRM <luxen@kit.edu>
Date: Fri, 20 Apr 2012 18:34:49 +0200
Subject: [PATCH] Contract trivial degree two ways.

---
 Contractor/EdgeBasedGraphFactory.cpp | 55 +++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/Contractor/EdgeBasedGraphFactory.cpp b/Contractor/EdgeBasedGraphFactory.cpp
index bfa09d84d..31e248433 100644
--- a/Contractor/EdgeBasedGraphFactory.cpp
+++ b/Contractor/EdgeBasedGraphFactory.cpp
@@ -25,6 +25,7 @@
 #include <boost/property_tree/ini_parser.hpp>
 
 #include "../Util/OpenMPReplacement.h"
+#include "../DataStructures/Percent.h"
 #include "EdgeBasedGraphFactory.h"
 
 template<>
@@ -197,12 +198,63 @@ void EdgeBasedGraphFactory::Run() {
     Percent p(_nodeBasedGraph->GetNumberOfNodes());
     int numberOfSkippedTurns(0);
     int nodeBasedEdgeCounter(0);
+    int triviallySkippedEdges(0);
+    
+    std::vector<std::pair<NodeID, NodeID> > edgesToRemove;
+    std::vector<_NodeBasedEdge > edgesToInsert;
+
+    //loop over graph and remove all trivially contractable edges.
+    for(_NodeBasedDynamicGraph::NodeIterator u = 0; u < _nodeBasedGraph->GetNumberOfNodes(); ++u ) {
+        for(_NodeBasedDynamicGraph::EdgeIterator e1 = _nodeBasedGraph->BeginEdges(u); e1 < _nodeBasedGraph->EndEdges(u); ++e1) {
+            _NodeBasedDynamicGraph::NodeIterator v = _nodeBasedGraph->GetTarget(e1);
+            const _NodeBasedDynamicGraph::EdgeData edgeData1 = _nodeBasedGraph->GetEdgeData(e1);
+            for(_NodeBasedDynamicGraph::EdgeIterator e2 = _nodeBasedGraph->BeginEdges(v); e2 < _nodeBasedGraph->EndEdges(v); ++e2) {
+                //TODO: Nur vorwärts-kanten und bei ungerichteten kanten nur eine richtung einfügen. Vorsicht!
+                const _NodeBasedDynamicGraph::EdgeData edgeData2 = _nodeBasedGraph->GetEdgeData(e2);
+                _NodeBasedDynamicGraph::NodeIterator w = _nodeBasedGraph->GetTarget(e2);
+                double testAngle = GetAngleBetweenTwoEdges(inputNodeInfoList[u], inputNodeInfoList[v], inputNodeInfoList[w]);
+                if((testAngle > 179 && testAngle < 181) && _nodeBasedGraph->GetOutDegree(v) <= 2 && edgeData1.nameID == edgeData2.nameID &&
+                        edgeData1.backward == edgeData2.backward && edgeData1.isAccessRestricted == edgeData2.isAccessRestricted) {
+
+                    //remove edges (u,v), (v,w)
+                    edgesToRemove.push_back(std::make_pair(u,v));
+                    edgesToRemove.push_back(std::make_pair(v,w));
+
+                    //add edge (v,w) with combined distance
+                    _NodeBasedEdge newEdge;
+                    newEdge.source = u; newEdge.target = w;
+                    newEdge.data = edgeData1; newEdge.data.distance += edgeData2.distance;
+                    ++triviallySkippedEdges;
+                    edgesToInsert.push_back(newEdge);
+                }
+            }
+        }
+    }
+
+    INFO("Inserting " << edgesToInsert.size() << " contracted edges");
+
+    Percent percent(edgesToInsert.size());
+    for(unsigned i = 0; i < 10; ++i) {
+        _nodeBasedGraph->DeleteEdge(edgesToRemove[2*i].first, edgesToRemove[2*i].second);
+        _nodeBasedGraph->DeleteEdge(edgesToRemove[2*i+1].first, edgesToRemove[2*i+1].second);
+
+        INFO("->delete edge (" << edgesToRemove[2*i].first << "," << edgesToRemove[2*i].second << ")");
+        INFO("->delete edge (" << edgesToRemove[2*i+1].first << "," << edgesToRemove[2*i+1].second << ")");
+
+        _NodeBasedEdge edge = edgesToInsert[i];
+        INFO("  inserted edge (" << edge.source << "," << edge.target << ") " << i << "/" << edgesToInsert.size());
+        assert(edge.source < _nodeBasedGraph->GetNumberOfNodes());
+        assert(edge.target < _nodeBasedGraph->GetNumberOfNodes());
+        _nodeBasedGraph->InsertEdge(edge.source, edge.target, edge.data);
+        percent.printIncrement();
+    }
+
+    INFO("Generating Edge-based Nodes");
 
     //loop over all edges and generate new set of nodes.
     for(_NodeBasedDynamicGraph::NodeIterator u = 0; u < _nodeBasedGraph->GetNumberOfNodes(); ++u ) {
         for(_NodeBasedDynamicGraph::EdgeIterator e1 = _nodeBasedGraph->BeginEdges(u); e1 < _nodeBasedGraph->EndEdges(u); ++e1) {
             _NodeBasedDynamicGraph::NodeIterator v = _nodeBasedGraph->GetTarget(e1);
-
             if(_nodeBasedGraph->GetEdgeData(e1).type != SHRT_MAX) {
                 assert(e1 != UINT_MAX);
                 assert(u != UINT_MAX);
@@ -270,6 +322,7 @@ void EdgeBasedGraphFactory::Run() {
     INFO("Edge-based graph contains " << edgeBasedEdges.size()    << " edges, blowup is " << (double)edgeBasedEdges.size()/(double)nodeBasedEdgeCounter);
     INFO("Edge-based graph skipped "  << numberOfSkippedTurns     << " turns, defined by " << numberOfTurnRestrictions << " restrictions.");
     INFO("Generated " << edgeBasedNodes.size() << " edge based nodes");
+    INFO("Trivially contracted edges: " << triviallySkippedEdges);
 }
 
 short EdgeBasedGraphFactory::AnalyzeTurn(const NodeID u, const NodeID v, const NodeID w) const {