210 lines
7.1 KiB
C++
210 lines
7.1 KiB
C++
/* ----------------------------------------------------------------------------
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* GTSAM Copyright 2010, Georgia Tech Research Corporation,
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* Atlanta, Georgia 30332-0415
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* All Rights Reserved
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* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
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* See LICENSE for the license information
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* -------------------------------------------------------------------------- */
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/**
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* @file VariableIndex.h
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* @brief
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* @author Richard Roberts
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* @created Sep 12, 2010
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*/
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#pragma once
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#include <gtsam/base/types.h>
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#include <gtsam/base/FastList.h>
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#include <gtsam/inference/Permutation.h>
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#include <vector>
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#include <iostream>
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#include <boost/shared_ptr.hpp>
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#include <boost/foreach.hpp>
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namespace gtsam {
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class Inference;
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/**
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* The VariableIndex class computes and stores the block column structure of a
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* factor graph. The factor graph stores a collection of factors, each of
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* which involves a set of variables. In contrast, the VariableIndex is built
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* from a factor graph prior to elimination, and stores the list of factors
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* that involve each variable. This information is stored as a vector of
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* lists of factor indices.
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*/
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class VariableIndex {
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public:
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typedef boost::shared_ptr<VariableIndex> shared_ptr;
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typedef FastList<size_t> Factors;
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typedef Factors::iterator Factor_iterator;
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typedef Factors::const_iterator Factor_const_iterator;
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protected:
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std::vector<Factors> indexUnpermuted_;
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Permuted<std::vector<Factors>, Factors&> index_; // Permuted view of indexUnpermuted.
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size_t nFactors_; // Number of factors in the original factor graph.
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size_t nEntries_; // Sum of involved variable counts of each factor.
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public:
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/** Default constructor, creates an empty VariableIndex */
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VariableIndex() : index_(indexUnpermuted_), nFactors_(0), nEntries_(0) {}
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/**
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* Create a VariableIndex that computes and stores the block column structure
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* of a factor graph. This constructor is used when the number of variables
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* is known beforehand.
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*/
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template<class FactorGraph> VariableIndex(const FactorGraph& factorGraph, Index nVariables);
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/**
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* Create a VariableIndex that computes and stores the block column structure
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* of a factor graph.
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*/
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template<class FactorGraph> VariableIndex(const FactorGraph& factorGraph);
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/**
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* The number of variable entries. This is one greater than the variable
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* with the highest index.
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*/
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Index size() const { return index_.size(); }
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/** The number of factors in the original factor graph */
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size_t nFactors() const { return nFactors_; }
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/** The number of nonzero blocks, i.e. the number of variable-factor entries */
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size_t nEntries() const { return nEntries_; }
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/** Access a list of factors by variable */
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const Factors& operator[](Index variable) const { checkVar(variable); return index_[variable]; }
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/** Access a list of factors by variable */
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Factors& operator[](Index variable) { checkVar(variable); return index_[variable]; }
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/**
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* Apply a variable permutation. Does not rearrange data, just permutes
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* future lookups by variable.
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*/
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void permute(const Permutation& permutation);
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/**
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* Augment the variable index with new factors. This can be used when
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* solving problems incrementally.
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*/
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template<class FactorGraph> void augment(const FactorGraph& factorGraph);
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/** Test for equality (for unit tests and debug assertions). */
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bool equals(const VariableIndex& other, double tol=0.0) const;
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/** Print the variable index (for unit tests and debugging). */
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void print(const std::string& str = "VariableIndex: ") const;
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protected:
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VariableIndex(size_t nVars) : indexUnpermuted_(nVars), index_(indexUnpermuted_), nFactors_(0), nEntries_(0) {}
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void checkVar(Index variable) const { assert(variable < index_.size()); }
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template<class FactorGraph> void fill(const FactorGraph& factorGraph);
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Factor_iterator factorsBegin(Index variable) { checkVar(variable); return index_[variable].begin(); }
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Factor_const_iterator factorsBegin(Index variable) const { checkVar(variable); return index_[variable].begin(); }
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Factor_iterator factorsEnd(Index variable) { checkVar(variable); return index_[variable].end(); }
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Factor_const_iterator factorsEnd(Index variable) const { checkVar(variable); return index_[variable].end(); }
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};
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/* ************************************************************************* */
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template<class FactorGraph>
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void VariableIndex::fill(const FactorGraph& factorGraph) {
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// Build index mapping from variable id to factor index
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for(size_t fi=0; fi<factorGraph.size(); ++fi)
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if(factorGraph[fi]) {
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BOOST_FOREACH(const Index key, factorGraph[fi]->keys()) {
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if(key < index_.size()) {
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index_[key].push_back(fi);
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++ nEntries_;
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}
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}
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++ nFactors_;
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}
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}
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/* ************************************************************************* */
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template<class FactorGraph>
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VariableIndex::VariableIndex(const FactorGraph& factorGraph) :
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index_(indexUnpermuted_), nFactors_(0), nEntries_(0) {
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// If the factor graph is empty, return an empty index because inside this
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// if block we assume at least one factor.
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if(factorGraph.size() > 0) {
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// Find highest-numbered variable
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Index maxVar = 0;
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BOOST_FOREACH(const typename FactorGraph::sharedFactor& factor, factorGraph) {
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if(factor) {
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BOOST_FOREACH(const Index key, factor->keys()) {
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if(key > maxVar)
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maxVar = key;
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}
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}
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}
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// Allocate array
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index_.container().resize(maxVar+1);
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index_.permutation() = Permutation::Identity(maxVar+1);
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fill(factorGraph);
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}
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}
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/* ************************************************************************* */
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template<class FactorGraph>
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VariableIndex::VariableIndex(const FactorGraph& factorGraph, Index nVariables) :
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indexUnpermuted_(nVariables), index_(indexUnpermuted_), nFactors_(0), nEntries_(0) {
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fill(factorGraph);
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}
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/* ************************************************************************* */
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template<class FactorGraph>
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void VariableIndex::augment(const FactorGraph& factorGraph) {
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// If the factor graph is empty, return an empty index because inside this
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// if block we assume at least one factor.
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if(factorGraph.size() > 0) {
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// Find highest-numbered variable
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Index maxVar = 0;
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BOOST_FOREACH(const typename FactorGraph::sharedFactor& factor, factorGraph) {
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if(factor) {
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BOOST_FOREACH(const Index key, factor->keys()) {
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if(key > maxVar)
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maxVar = key;
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}
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}
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}
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// Allocate index
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Index originalSize = index_.size();
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index_.container().resize(std::max(index_.size(), maxVar+1));
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index_.permutation().resize(index_.container().size());
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for(Index var=originalSize; var<index_.permutation().size(); ++var)
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index_.permutation()[var] = var;
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// Augment index mapping from variable id to factor index
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size_t orignFactors = nFactors_;
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for(size_t fi=0; fi<factorGraph.size(); ++fi)
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if(factorGraph[fi]) {
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BOOST_FOREACH(const Index key, factorGraph[fi]->keys()) {
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index_[key].push_back(orignFactors + fi);
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++ nEntries_;
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}
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++ nFactors_;
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}
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}
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}
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}
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