DecisionTree.h

Go to the documentation of this file.

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

 * 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/Assignment.h>
#include <boost/function.hpp>
#include <iostream>
#include <vector>
#include <map>

namespace gtsam {

  template<typename L, typename Y>
  class DecisionTree {

  public:

    typedef boost::function<Y(const Y&)> Unary;
    typedef boost::function<Y(const Y&, const Y&)> Binary;

    typedef std::pair<L,size_t> LabelC;

    class Leaf;
    class Choice;

    class Node {
    public:
      typedef boost::shared_ptr<const Node> Ptr;

#ifdef DT_DEBUG_MEMORY
      static int nrNodes;
#endif

      // Constructor
      Node() {
#ifdef DT_DEBUG_MEMORY
      std::cout << ++nrNodes << " constructed " << id() << std::endl; std::cout.flush();
#endif
      }

      // Destructor
      virtual ~Node() {
#ifdef DT_DEBUG_MEMORY
      std::cout << --nrNodes << " destructed " << id() << std::endl; std::cout.flush();
#endif
      }

      // Unique ID for dot files
      const void* id() const { return this; }

      // everything else is virtual, no documentation here as internal
      virtual void print(const std::string& s = "") const = 0;
      virtual void dot(std::ostream& os, bool showZero) const = 0;
      virtual bool sameLeaf(const Leaf& q) const = 0;
      virtual bool sameLeaf(const Node& q) const = 0;
      virtual bool equals(const Node& other, double tol = 1e-9) const = 0;
      virtual const Y& operator()(const Assignment<L>& x) const = 0;
      virtual Ptr apply(const Unary& op) const = 0;
      virtual Ptr apply_f_op_g(const Node&, const Binary&) const = 0;
      virtual Ptr apply_g_op_fL(const Leaf&, const Binary&) const = 0;
      virtual Ptr apply_g_op_fC(const Choice&, const Binary&) const = 0;
      virtual Ptr choose(const L& label, size_t index) const = 0;
      virtual bool isLeaf() const = 0;
    };
  public:

    typedef typename Node::Ptr NodePtr;

    /* a DecisionTree just contains the root */
    NodePtr root_;

  protected:

    template<typename It, typename ValueIt>
    NodePtr create(It begin, It end, ValueIt beginY, ValueIt endY) const;

    template<typename M, typename X> NodePtr
    convert(const typename DecisionTree<M, X>::NodePtr& f, const std::map<M,
        L>& map, boost::function<Y(const X&)> op);

    DecisionTree();

  public:


    DecisionTree(const Y& y);

    DecisionTree(const L& label, const Y& y1, const Y& y2);

    DecisionTree(const LabelC& label, const Y& y1, const Y& y2);

    DecisionTree(const std::vector<LabelC>& labelCs, const std::vector<Y>& ys);

    DecisionTree(const std::vector<LabelC>& labelCs, const std::string& table);

    template<typename Iterator>
    DecisionTree(Iterator begin, Iterator end, const L& label);

    DecisionTree(const L& label, //
        const DecisionTree& f0, const DecisionTree& f1);

    template<typename M, typename X>
    DecisionTree(const DecisionTree<M, X>& other,
        const std::map<M, L>& map, boost::function<Y(const X&)> op);


    void print(const std::string& s = "DecisionTree") const;

    // Testable
    bool equals(const DecisionTree& other, double tol = 1e-9) const;


    virtual ~DecisionTree() {
    }

    bool operator==(const DecisionTree& q) const;

    const Y& operator()(const Assignment<L>& x) const;

    DecisionTree apply(const Unary& op) const;

    DecisionTree apply(const DecisionTree& g, const Binary& op) const;

    DecisionTree choose(const L& label, size_t index) const {
      NodePtr newRoot = root_->choose(label, index);
      return DecisionTree(newRoot);
    }

    DecisionTree combine(const L& label, size_t cardinality, const Binary& op) const;

    DecisionTree combine(const LabelC& labelC, const Binary& op) const {
      return combine(labelC.first, labelC.second, op);
    }

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

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


    // internal use only
    DecisionTree(const NodePtr& root);

    // internal use only
    template<typename Iterator> NodePtr
    compose(Iterator begin, Iterator end, const L& label) const;


  }; // DecisionTree

  template<typename Y, typename L>
  DecisionTree<L, Y> apply(const DecisionTree<L, Y>& f,
      const typename DecisionTree<L, Y>::Unary& op) {
    return f.apply(op);
  }

  template<typename Y, typename L>
  DecisionTree<L, Y> apply(const DecisionTree<L, Y>& f,
      const DecisionTree<L, Y>& g,
      const typename DecisionTree<L, Y>::Binary& op) {
    return f.apply(g, op);
  }

} // namespace gtsam