EliminateableFactorGraph.h

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/* ----------------------------------------------------------------------------

 * GTSAM Copyright 2010, Georgia Tech Research Corporation,
 * Atlanta, Georgia 30332-0415
 * All Rights Reserved
 * Authors: Frank Dellaert, et al. (see THANKS for the full author list)

 * See LICENSE for the license information

 * -------------------------------------------------------------------------- */

#pragma once

#include <boost/shared_ptr.hpp>
#include <boost/function.hpp>
#include <boost/variant.hpp>
#include <boost/optional.hpp>

#include <gtsam/inference/Ordering.h>
#include <gtsam/inference/VariableIndex.h>

namespace gtsam {

  template<class GRAPH>
  struct EliminationTraits
  {
    // Template for deriving:
    // typedef MyFactor FactorType;                   ///< Type of factors in factor graph (e.g. GaussianFactor)
    // typedef MyFactorGraphType FactorGraphType;     ///< Type of the factor graph (e.g. GaussianFactorGraph)
    // typedef MyConditional ConditionalType;         ///< Type of conditionals from elimination (e.g. GaussianConditional)
    // typedef MyBayesNet BayesNetType;               ///< Type of Bayes net from sequential elimination (e.g. GaussianBayesNet)
    // typedef MyEliminationTree EliminationTreeType; ///< Type of elimination tree (e.g. GaussianEliminationTree)
    // typedef MyBayesTree BayesTreeType;             ///< Type of Bayes tree (e.g. GaussianBayesTree)
    // typedef MyJunctionTree JunctionTreeType;       ///< Type of Junction tree (e.g. GaussianJunctionTree)
    // static pair<shared_ptr<ConditionalType>, shared_ptr<FactorType>
    //   DefaultEliminate(
    //   const MyFactorGraph& factors, const Ordering& keys); ///< The default dense elimination function
  };


  template<class FACTORGRAPH>
  class EliminateableFactorGraph
  {
  private:
    typedef EliminateableFactorGraph<FACTORGRAPH> This; 
    typedef FACTORGRAPH FactorGraphType; 
    // Base factor type stored in this graph (private because derived classes will get this from
    // their FactorGraph base class)
    typedef typename EliminationTraits<FactorGraphType>::FactorType _FactorType;

  public:
    typedef EliminationTraits<FactorGraphType> EliminationTraitsType;

    typedef typename EliminationTraitsType::ConditionalType ConditionalType;

    typedef typename EliminationTraitsType::BayesNetType BayesNetType;

    typedef typename EliminationTraitsType::EliminationTreeType EliminationTreeType;

    typedef typename EliminationTraitsType::BayesTreeType BayesTreeType;

    typedef typename EliminationTraitsType::JunctionTreeType JunctionTreeType;

    typedef std::pair<boost::shared_ptr<ConditionalType>, boost::shared_ptr<_FactorType> > EliminationResult;

    typedef boost::function<EliminationResult(const FactorGraphType&, const Ordering&)> Eliminate;

    typedef boost::optional<const Ordering&> OptionalOrdering;

    typedef boost::optional<const VariableIndex&> OptionalVariableIndex;

    boost::shared_ptr<BayesNetType> eliminateSequential(
      OptionalOrdering ordering = boost::none,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

    boost::shared_ptr<BayesTreeType> eliminateMultifrontal(
      OptionalOrdering ordering = boost::none,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

    std::pair<boost::shared_ptr<BayesNetType>, boost::shared_ptr<FactorGraphType> >
      eliminatePartialSequential(
      const Ordering& ordering,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

    std::pair<boost::shared_ptr<BayesNetType>, boost::shared_ptr<FactorGraphType> >
      eliminatePartialSequential(
      const std::vector<Key>& variables,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

    std::pair<boost::shared_ptr<BayesTreeType>, boost::shared_ptr<FactorGraphType> >
      eliminatePartialMultifrontal(
      const Ordering& ordering,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;
    
    std::pair<boost::shared_ptr<BayesTreeType>, boost::shared_ptr<FactorGraphType> >
      eliminatePartialMultifrontal(
      const std::vector<Key>& variables,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

    boost::shared_ptr<BayesNetType> marginalMultifrontalBayesNet(
      boost::variant<const Ordering&, const std::vector<Key>&> variables,
      OptionalOrdering marginalizedVariableOrdering = boost::none,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

    boost::shared_ptr<BayesTreeType> marginalMultifrontalBayesTree(
      boost::variant<const Ordering&, const std::vector<Key>&> variables,
      OptionalOrdering marginalizedVariableOrdering = boost::none,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

    boost::shared_ptr<FactorGraphType> marginal(
      const std::vector<Key>& variables,
      const Eliminate& function = EliminationTraitsType::DefaultEliminate,
      OptionalVariableIndex variableIndex = boost::none) const;

  private:

    // Access the derived factor graph class
    const FactorGraphType& asDerived() const { return static_cast<const FactorGraphType&>(*this); }

    // Access the derived factor graph class
    FactorGraphType& asDerived() { return static_cast<FactorGraphType&>(*this); }
  };

}