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// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2015 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: sameeragarwal@google.com (Sameer Agarwal)
#ifndef CERES_INTERNAL_GRAPH_H_
#define CERES_INTERNAL_GRAPH_H_
#include <limits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include "ceres/internal/export.h"
#include "ceres/map_util.h"
#include "ceres/pair_hash.h"
#include "ceres/types.h"
#include "glog/logging.h"
namespace ceres {
namespace internal {
// A unweighted undirected graph templated over the vertex ids. Vertex
// should be hashable.
template <typename Vertex>
class CERES_NO_EXPORT Graph {
public:
// Add a vertex.
void AddVertex(const Vertex& vertex) {
if (vertices_.insert(vertex).second) {
edges_[vertex] = std::unordered_set<Vertex>();
}
}
bool RemoveVertex(const Vertex& vertex) {
if (vertices_.find(vertex) == vertices_.end()) {
return false;
}
vertices_.erase(vertex);
const std::unordered_set<Vertex>& sinks = edges_[vertex];
for (const Vertex& s : sinks) {
edges_[s].erase(vertex);
}
edges_.erase(vertex);
return true;
}
// Add an edge between the vertex1 and vertex2. Calling AddEdge on a
// pair of vertices which do not exist in the graph yet will result
// in undefined behavior.
//
// It is legal to call this method repeatedly for the same set of
// vertices.
void AddEdge(const Vertex& vertex1, const Vertex& vertex2) {
DCHECK(vertices_.find(vertex1) != vertices_.end());
DCHECK(vertices_.find(vertex2) != vertices_.end());
if (edges_[vertex1].insert(vertex2).second) {
edges_[vertex2].insert(vertex1);
}
}
// Calling Neighbors on a vertex not in the graph will result in
// undefined behaviour.
const std::unordered_set<Vertex>& Neighbors(const Vertex& vertex) const {
return FindOrDie(edges_, vertex);
}
const std::unordered_set<Vertex>& vertices() const { return vertices_; }
private:
std::unordered_set<Vertex> vertices_;
std::unordered_map<Vertex, std::unordered_set<Vertex>> edges_;
};
// A weighted undirected graph templated over the vertex ids. Vertex
// should be hashable and comparable.
template <typename Vertex>
class WeightedGraph {
public:
// Add a weighted vertex. If the vertex already exists in the graph,
// its weight is set to the new weight.
void AddVertex(const Vertex& vertex, double weight) {
if (vertices_.find(vertex) == vertices_.end()) {
vertices_.insert(vertex);
edges_[vertex] = std::unordered_set<Vertex>();
}
vertex_weights_[vertex] = weight;
}
// Uses weight = 1.0. If vertex already exists, its weight is set to
// 1.0.
void AddVertex(const Vertex& vertex) { AddVertex(vertex, 1.0); }
bool RemoveVertex(const Vertex& vertex) {
if (vertices_.find(vertex) == vertices_.end()) {
return false;
}
vertices_.erase(vertex);
vertex_weights_.erase(vertex);
const std::unordered_set<Vertex>& sinks = edges_[vertex];
for (const Vertex& s : sinks) {
if (vertex < s) {
edge_weights_.erase(std::make_pair(vertex, s));
} else {
edge_weights_.erase(std::make_pair(s, vertex));
}
edges_[s].erase(vertex);
}
edges_.erase(vertex);
return true;
}
// Add a weighted edge between the vertex1 and vertex2. Calling
// AddEdge on a pair of vertices which do not exist in the graph yet
// will result in undefined behavior.
//
// It is legal to call this method repeatedly for the same set of
// vertices.
void AddEdge(const Vertex& vertex1, const Vertex& vertex2, double weight) {
DCHECK(vertices_.find(vertex1) != vertices_.end());
DCHECK(vertices_.find(vertex2) != vertices_.end());
if (edges_[vertex1].insert(vertex2).second) {
edges_[vertex2].insert(vertex1);
}
if (vertex1 < vertex2) {
edge_weights_[std::make_pair(vertex1, vertex2)] = weight;
} else {
edge_weights_[std::make_pair(vertex2, vertex1)] = weight;
}
}
// Uses weight = 1.0.
void AddEdge(const Vertex& vertex1, const Vertex& vertex2) {
AddEdge(vertex1, vertex2, 1.0);
}
// Calling VertexWeight on a vertex not in the graph will result in
// undefined behavior.
double VertexWeight(const Vertex& vertex) const {
return FindOrDie(vertex_weights_, vertex);
}
// Calling EdgeWeight on a pair of vertices where either one of the
// vertices is not present in the graph will result in undefined
// behaviour. If there is no edge connecting vertex1 and vertex2,
// the edge weight is zero.
double EdgeWeight(const Vertex& vertex1, const Vertex& vertex2) const {
if (vertex1 < vertex2) {
return FindWithDefault(
edge_weights_, std::make_pair(vertex1, vertex2), 0.0);
} else {
return FindWithDefault(
edge_weights_, std::make_pair(vertex2, vertex1), 0.0);
}
}
// Calling Neighbors on a vertex not in the graph will result in
// undefined behaviour.
const std::unordered_set<Vertex>& Neighbors(const Vertex& vertex) const {
return FindOrDie(edges_, vertex);
}
const std::unordered_set<Vertex>& vertices() const { return vertices_; }
static double InvalidWeight() {
return std::numeric_limits<double>::quiet_NaN();
}
private:
std::unordered_set<Vertex> vertices_;
std::unordered_map<Vertex, double> vertex_weights_;
std::unordered_map<Vertex, std::unordered_set<Vertex>> edges_;
std::unordered_map<std::pair<Vertex, Vertex>, double, pair_hash>
edge_weights_;
};
} // namespace internal
} // namespace ceres
#endif // CERES_INTERNAL_GRAPH_H_
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