DecisionTree.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/Assignment.h>
 
#include <boost/function.hpp>
#include <functional>
#include <iostream>
#include <map>
#include <vector>
 
namespace gtsam {
 
  template<typename L, typename Y>
  class DecisionTree {
 
  public:
 
    typedef std::function<Y(const Y&)> Unary;
    typedef std::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, std::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, std::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