DecisionTreeFactor.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 <gtsam/discrete/AlgebraicDecisionTree.h>
#include <gtsam/discrete/DiscreteFactor.h>
#include <gtsam/discrete/DiscreteKey.h>
#include <gtsam/inference/Ordering.h>

#include <algorithm>
#include <memory>
#include <map>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

namespace gtsam {

  class DiscreteConditional;
  class HybridValues;

  class GTSAM_EXPORT DecisionTreeFactor : public DiscreteFactor,
                                          public AlgebraicDecisionTree<Key> {
   public:
    // typedefs needed to play nice with gtsam
    typedef DecisionTreeFactor This;
    typedef DiscreteFactor Base;  
    typedef std::shared_ptr<DecisionTreeFactor> shared_ptr;
    typedef AlgebraicDecisionTree<Key> ADT;

   protected:
    std::map<Key, size_t> cardinalities_;

   public:

    DecisionTreeFactor();

    DecisionTreeFactor(const DiscreteKeys& keys, const ADT& potentials);

    DecisionTreeFactor(const DiscreteKeys& keys,
                      const std::vector<double>& table);

    DecisionTreeFactor(const DiscreteKeys& keys, const std::string& table);

    template <class SOURCE>
    DecisionTreeFactor(const DiscreteKey& key, SOURCE table)
        : DecisionTreeFactor(DiscreteKeys{key}, table) {}

    DecisionTreeFactor(const DiscreteKey& key, const std::vector<double>& row)
        : DecisionTreeFactor(DiscreteKeys{key}, row) {}

    explicit DecisionTreeFactor(const DiscreteConditional& c);


    bool equals(const DiscreteFactor& other, double tol = 1e-9) const override;

    // print
    void print(
        const std::string& s = "DecisionTreeFactor:\n",
        const KeyFormatter& formatter = DefaultKeyFormatter) const override;


    double evaluate(const DiscreteValues& values) const  {
      return ADT::operator()(values);
    }

    double operator()(const DiscreteValues& values) const override {
      return ADT::operator()(values);
    }

    double error(const DiscreteValues& values) const;

    DecisionTreeFactor operator*(const DecisionTreeFactor& f) const override {
      return apply(f, ADT::Ring::mul);
    }

    static double safe_div(const double& a, const double& b);

    size_t cardinality(Key j) const { return cardinalities_.at(j); }

    DecisionTreeFactor operator/(const DecisionTreeFactor& f) const {
      return apply(f, safe_div);
    }

    DecisionTreeFactor toDecisionTreeFactor() const override { return *this; }

    shared_ptr sum(size_t nrFrontals) const {
      return combine(nrFrontals, ADT::Ring::add);
    }

    shared_ptr sum(const Ordering& keys) const {
      return combine(keys, ADT::Ring::add);
    }

    shared_ptr max(size_t nrFrontals) const {
      return combine(nrFrontals, ADT::Ring::max);
    }

    shared_ptr max(const Ordering& keys) const {
      return combine(keys, ADT::Ring::max);
    }


    DecisionTreeFactor apply(const DecisionTreeFactor& f, ADT::Binary op) const;

    shared_ptr combine(size_t nrFrontals, ADT::Binary op) const;

    shared_ptr combine(const Ordering& keys, ADT::Binary op) const;

    std::vector<std::pair<DiscreteValues, double>> enumerate() const;

    DiscreteKeys discreteKeys() const;

    DecisionTreeFactor prune(size_t maxNrAssignments) const;


    void dot(std::ostream& os,
            const KeyFormatter& keyFormatter = DefaultKeyFormatter,
            bool showZero = true) const;

    void dot(const std::string& name,
            const KeyFormatter& keyFormatter = DefaultKeyFormatter,
            bool showZero = true) const;

    std::string dot(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
                    bool showZero = true) const;

    std::string markdown(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
                        const Names& names = {}) const override;

    std::string html(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
                    const Names& names = {}) const override;


  double error(const HybridValues& values) const override;


   private:
#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION

    friend class boost::serialization::access;
    template <class ARCHIVE>
    void serialize(ARCHIVE& ar, const unsigned int /*version*/) {
      ar& BOOST_SERIALIZATION_BASE_OBJECT_NVP(Base);
      ar& BOOST_SERIALIZATION_BASE_OBJECT_NVP(ADT);
      ar& BOOST_SERIALIZATION_NVP(cardinalities_);
    }
#endif
  };

// traits
template <>
struct traits<DecisionTreeFactor> : public Testable<DecisionTreeFactor> {};
}  // namespace gtsam