1 // Ceres Solver - A fast non-linear least squares minimizer 2 // Copyright 2010, 2011, 2012 Google Inc. All rights reserved. 3 // http://code.google.com/p/ceres-solver/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are met: 7 // 8 // * Redistributions of source code must retain the above copyright notice, 9 // this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above copyright notice, 11 // this list of conditions and the following disclaimer in the documentation 12 // and/or other materials provided with the distribution. 13 // * Neither the name of Google Inc. nor the names of its contributors may be 14 // used to endorse or promote products derived from this software without 15 // specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 18 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 21 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 22 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 27 // POSSIBILITY OF SUCH DAMAGE. 28 // 29 // Author: sameeragarwal@google.com (Sameer Agarwal) 30 31 #ifndef CERES_INTERNAL_GRAPH_H_ 32 #define CERES_INTERNAL_GRAPH_H_ 33 34 #include <limits> 35 #include <utility> 36 #include "ceres/integral_types.h" 37 #include "ceres/map_util.h" 38 #include "ceres/collections_port.h" 39 #include "ceres/internal/macros.h" 40 #include "ceres/types.h" 41 #include "glog/logging.h" 42 43 namespace ceres { 44 namespace internal { 45 46 // A weighted undirected graph templated over the vertex ids. Vertex 47 // should be hashable and comparable. 48 template <typename Vertex> 49 class Graph { 50 public: Graph()51 Graph() {} 52 53 // Add a weighted vertex. If the vertex already exists in the graph, 54 // its weight is set to the new weight. AddVertex(const Vertex & vertex,double weight)55 void AddVertex(const Vertex& vertex, double weight) { 56 if (vertices_.find(vertex) == vertices_.end()) { 57 vertices_.insert(vertex); 58 edges_[vertex] = HashSet<Vertex>(); 59 } 60 vertex_weights_[vertex] = weight; 61 } 62 63 // Uses weight = 1.0. If vertex already exists, its weight is set to 64 // 1.0. AddVertex(const Vertex & vertex)65 void AddVertex(const Vertex& vertex) { 66 AddVertex(vertex, 1.0); 67 } 68 RemoveVertex(const Vertex & vertex)69 bool RemoveVertex(const Vertex& vertex) { 70 if (vertices_.find(vertex) == vertices_.end()) { 71 return false; 72 } 73 74 vertices_.erase(vertex); 75 vertex_weights_.erase(vertex); 76 const HashSet<Vertex>& sinks = edges_[vertex]; 77 for (typename HashSet<Vertex>::const_iterator it = sinks.begin(); 78 it != sinks.end(); ++it) { 79 if (vertex < *it) { 80 edge_weights_.erase(make_pair(vertex, *it)); 81 } else { 82 edge_weights_.erase(make_pair(*it, vertex)); 83 } 84 edges_[*it].erase(vertex); 85 } 86 87 edges_.erase(vertex); 88 return true; 89 } 90 91 // Add a weighted edge between the vertex1 and vertex2. Calling 92 // AddEdge on a pair of vertices which do not exist in the graph yet 93 // will result in undefined behavior. 94 // 95 // It is legal to call this method repeatedly for the same set of 96 // vertices. AddEdge(const Vertex & vertex1,const Vertex & vertex2,double weight)97 void AddEdge(const Vertex& vertex1, const Vertex& vertex2, double weight) { 98 DCHECK(vertices_.find(vertex1) != vertices_.end()); 99 DCHECK(vertices_.find(vertex2) != vertices_.end()); 100 101 if (edges_[vertex1].insert(vertex2).second) { 102 edges_[vertex2].insert(vertex1); 103 } 104 105 if (vertex1 < vertex2) { 106 edge_weights_[make_pair(vertex1, vertex2)] = weight; 107 } else { 108 edge_weights_[make_pair(vertex2, vertex1)] = weight; 109 } 110 } 111 112 // Uses weight = 1.0. AddEdge(const Vertex & vertex1,const Vertex & vertex2)113 void AddEdge(const Vertex& vertex1, const Vertex& vertex2) { 114 AddEdge(vertex1, vertex2, 1.0); 115 } 116 117 // Calling VertexWeight on a vertex not in the graph will result in 118 // undefined behavior. VertexWeight(const Vertex & vertex)119 double VertexWeight(const Vertex& vertex) const { 120 return FindOrDie(vertex_weights_, vertex); 121 } 122 123 // Calling EdgeWeight on a pair of vertices where either one of the 124 // vertices is not present in the graph will result in undefined 125 // behaviour. If there is no edge connecting vertex1 and vertex2, 126 // the edge weight is zero. EdgeWeight(const Vertex & vertex1,const Vertex & vertex2)127 double EdgeWeight(const Vertex& vertex1, const Vertex& vertex2) const { 128 if (vertex1 < vertex2) { 129 return FindWithDefault(edge_weights_, make_pair(vertex1, vertex2), 0.0); 130 } else { 131 return FindWithDefault(edge_weights_, make_pair(vertex2, vertex1), 0.0); 132 } 133 } 134 135 // Calling Neighbors on a vertex not in the graph will result in 136 // undefined behaviour. Neighbors(const Vertex & vertex)137 const HashSet<Vertex>& Neighbors(const Vertex& vertex) const { 138 return FindOrDie(edges_, vertex); 139 } 140 vertices()141 const HashSet<Vertex>& vertices() const { 142 return vertices_; 143 } 144 InvalidWeight()145 static double InvalidWeight() { 146 return std::numeric_limits<double>::quiet_NaN(); 147 }; 148 149 private: 150 HashSet<Vertex> vertices_; 151 HashMap<Vertex, double> vertex_weights_; 152 HashMap<Vertex, HashSet<Vertex> > edges_; 153 HashMap<pair<Vertex, Vertex>, double> edge_weights_; 154 155 CERES_DISALLOW_COPY_AND_ASSIGN(Graph); 156 }; 157 158 } // namespace internal 159 } // namespace ceres 160 161 #endif // CERES_INTERNAL_GRAPH_H_ 162