92 lines
2.8 KiB
C++
92 lines
2.8 KiB
C++
/**
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* @file EliminationTree.h
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* @brief
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* @author Frank Dellaert
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* @created Oct 13, 2010
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*/
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#pragma once
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#include <list>
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#include <string>
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#include <utility>
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#include <boost/pool/pool_alloc.hpp>
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#include <gtsam/inference/VariableIndex.h>
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#include <gtsam/inference/BayesNet.h>
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#include <gtsam/inference/FactorGraph.h>
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class EliminationTreeTester; // for unit tests, see testEliminationTree
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namespace gtsam {
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/**
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* An elimination tree is a data structure used intermediately during
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* elimination, and it can be used to save work between multiple eliminations.
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*/
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template<class FACTOR>
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class EliminationTree: public Testable<EliminationTree<FACTOR> > {
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public:
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typedef typename FACTOR::shared_ptr sharedFactor;
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typedef boost::shared_ptr<EliminationTree<FACTOR> > shared_ptr;
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typedef gtsam::BayesNet<typename FACTOR::Conditional> BayesNet;
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private:
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typedef std::list<sharedFactor, boost::fast_pool_allocator<sharedFactor> > Factors;
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typedef std::list<shared_ptr, boost::fast_pool_allocator<shared_ptr> > SubTrees;
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typedef std::vector<typename FACTOR::Conditional::shared_ptr> Conditionals;
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Index key_; /** index associated with root */
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Factors factors_; /** factors associated with root */
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SubTrees subTrees_; /** sub-trees */
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/** default constructor, private, as you should use Create below */
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EliminationTree(Index key = 0) : key_(key) {}
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/** add a factor, for Create use only */
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void add(const sharedFactor& factor) { factors_.push_back(factor); }
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/** add a subtree, for Create use only */
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void add(const shared_ptr& child) { subTrees_.push_back(child); }
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/**
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* Static internal function to build a vector of parent pointers using the
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* algorithm of Gilbert et al., 2001, BIT.
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*/
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static std::vector<Index> ComputeParents(const VariableIndex& structure);
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/**
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* Recursive routine that eliminates the factors arranged in an elimination tree
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*/
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sharedFactor eliminate_(Conditionals& conditionals) const;
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// Allow access to constructor and add methods for testing purposes
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friend class ::EliminationTreeTester;
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public:
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/**
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* Named constructor to build the elimination tree of a factor graph using
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* pre-computed column structure.
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*/
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template<class DERIVEDFACTOR>
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static shared_ptr Create(const FactorGraph<DERIVEDFACTOR>& factorGraph, const VariableIndex& structure);
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/** Named constructor to build the elimination tree of a factor graph */
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template<class DERIVEDFACTOR>
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static shared_ptr Create(const FactorGraph<DERIVEDFACTOR>& factorGraph);
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/** Print the tree to cout */
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void print(const std::string& name = "EliminationTree: ") const;
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/** Test whether the tree is equal to another */
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bool equals(const EliminationTree& other, double tol = 1e-9) const;
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/** Eliminate the factors to a Bayes Net */
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typename BayesNet::shared_ptr eliminate() const;
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};
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}
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