densitytreenode.hpp

dysii是一款非常出色的滤波函数库

#ifndef INDII_ML_AUX_DENSITYTREENODE_HPP
#define INDII_ML_AUX_DENSITYTREENODE_HPP

#include "vector.hpp"
#include "matrix.hpp"

namespace indii {
  namespace ml {
    namespace aux {
/**
 * Node of a density tree.
 *
 * @author Lawrence Murray <[e-mail]>
 * @version $Rev: 401 $
 * @date $Date: 2008-03-05 13:54:28 +0000 (Wed, 05 Mar 2008) $
 *
 * A node has a weight \f$w\f$, volume \f$v\f$ and density \f$\delta\f$,
 * related by the identity \f$w = \delta v\f$.
 *
 * @section DensityTreeInternal_serialization Serialization
 *
 * This class supports serialization through the Boost.Serialization
 * library.
 */
class DensityTreeNode {
public:
  /**
   * Default constructor.
   *
   * This should generally only be used when the object is to be
   * restored from a serialization.
   */
  DensityTreeNode();

  /**
   * Constructor.
   *
   * @param lower Lower bound on the hyper-rectangle of the node.
   * @param upper Upper bound on the hyper-rectangle of the node.
   * @param weight \f$w\f$; weight of the node.
   * @param volume \f$v\f$; volume of the node.
   *
   * The density across the node will be calculated as
   * \f$\delta = w/v\f$.
   */
  DensityTreeNode(const vector& lower, const vector& upper,
      const double weight, const double volume);

  /**
   * Destructor.
   */
  virtual ~DensityTreeNode();

  /**
   * Get the weight of the node.
   *
   * @return \f$w\f$; the weight of the node.
   */
  double getWeight() const;

  /**
   * Get the volume of the node.
   *
   * @return \f$v\f$; the volume of the node.
   */
  double getVolume() const;

  /**
   * Get the density of the node.
   *
   * @return \f$\delta\f$; the density of the node.
   */
  double getDensity() const;
  
  /**
   * Provide contribution to the expectation sum.
   *
   * @return Contribution to the expectation sum.
   */
  virtual vector sumExpectation() = 0;

  /**
   * Provide contribution to the covariance sum.
   *
   * @return Contribution to the expectation sum.
   */
  virtual symmetric_matrix sumCovariance() = 0;

  /**
   * Sample from the tree.
   *
   * @param u Random number between 0 and the total weight of the node.
   *
   * @return A sample from the tree.
   */
  virtual vector sample(const double u) = 0;

  /**
   * Calculate the density at a given point.
   *
   * @param x \f$\mathbf{x}\f$; point at which to evaluate the
   * density.
   *
   * @return \f$p(\mathbf{x})\f$; the density at \f$\mathbf{x}\f$.
   */
  virtual double densityAt(const vector& x) = 0;

  /**
   * Get lower bound on the hyper-rectangle of the node.
   *
   * @return Lower bound on the hyper-rectangle of the node.
   */
  const vector& getLower() const;

  /**
   * Get upper bound on the hyper-rectangle of the node.
   *
   * @return Upper bound on the hyper-rectangle of the node.
   */
 const vector& getUpper() const;

private:
  /**
   * Weight of the node.
   */
  double weight;
   
  /**
   * Volume of the node.
   */
  double volume;
  
  /**
   * Density of the node.
   */
  double density;

  /**
   * Lower bound on the hyper-rectangle of the node.
   */
  vector lower;
  
  /**
   * Upper bound on the hyper-rectangle of the node.
   */
  vector upper;

  /**
   * Serialize, or restore from serialization.
   */
  template<class Archive>
  void serialize(Archive& ar, const unsigned int version);

  /*
   * Boost.Serialization requirements.
   */
  friend class boost::serialization::access;

};

    }
  }
}

template<class Archive>
void indii::ml::aux::DensityTreeNode::serialize(Archive& ar,
    const unsigned int version) {
  ar & weight;
  ar & volume;
  ar & density;
  ar & lower;
  ar & upper;
  
  /* post-condition */
  assert (weight > 0.0);
  assert (volume > 0.0);
  assert (density > 0.0);
  assert (lower.size() == upper.size());
}

inline double indii::ml::aux::DensityTreeNode::getWeight() const {
  return weight;
}

inline double indii::ml::aux::DensityTreeNode::getVolume() const {
  return volume;
}

inline double indii::ml::aux::DensityTreeNode::getDensity() const {
  return density;
}

inline const indii::ml::aux::vector& indii::ml::aux::DensityTreeNode::getLower()
    const {
  return lower;
}

inline const indii::ml::aux::vector& indii::ml::aux::DensityTreeNode::getUpper()
    const {
  return upper;
}

#endif