NICE_VisLearning/classifier/fpclassifier/randomforest/DTBOblique.h

/**
 * @file DTBOblique.h
 * @brief oblique decision tree
 * @author Sven Sickert
 * @date 10/15/2014

*/
#ifndef DTBOBLIQUEINCLUDE
#define DTBOBLIQUEINCLUDE

#include "core/vector/VectorT.h"
#include "core/vector/MatrixT.h"

#include "core/basics/Config.h"
#include "DecisionTreeBuilder.h"
#include "vislearning/cbaselib/CachedExample.h"


namespace OBJREC {

struct SplitInfo {
    double threshold;
    double informationGain;
    double entropyLeft;
    double entropyRight;
    double *distLeft;
    double *distRight;
    NICE::Vector params;
};

/** random oblique decision tree */
class DTBOblique : public DecisionTreeBuilder
{
  protected:

    /////////////////////////
    /////////////////////////
    // PROTECTED VARIABLES //
    /////////////////////////
    /////////////////////////

    /** Whether to use shannon entropy or not */
    bool useShannonEntropy;

    /** Whether to save indices in leaves or not */
    bool saveIndices;

    /** Whether to use one-vs-one or one-vs-all for multiclass scenarios */
    bool useOneVsOne;

    /** Amount of steps for complete search for best threshold */
    int splitSteps;

    /** Maximum allowed depth of a tree */
    int maxDepth;

    /* Minimum amount of features in a leaf node */
    int minExamples;

    /** Regularization type */
    int regularizationType;

    /** Minimum entropy to continue with splitting */
    double minimumEntropy;

    /** Minimum information gain to continue with splitting */
    double minimumInformationGain;

    /** Regularization parameter */
    double lambdaInit;

    /////////////////////////
    /////////////////////////
    //  PROTECTED METHODS  //
    /////////////////////////
    /////////////////////////

    /**
    * @brief get data matrix X and label vector y
    * @param fp feature pool
    * @param examples all examples of the training
    * @param examples_selection indeces of selected example subset
    * @param matX data matrix (amountExamples x amountParameters)
    * @param vecY label vector (amountExamples)
    */
    void getDataAndLabel(
            const FeaturePool &fp,
            const Examples &examples,
            const std::vector<int> & examples_selection,
            NICE::Matrix &matX,
            NICE::Vector &vecY );

    /**
     * @brief return a regularization matrix of size (dimParams)x(dimParams)
     * @param X data matrix
     * @param XTXreg return regularized X'*X
     * @param regOption which kind of regularization
     * @param lambda regularization parameter (weigthing)
     */
    void regularizeDataMatrix (
            const NICE::Matrix & X,
            NICE::Matrix &XTXreg,
            const int regOption,
            const double lambda );

    /**
     * @brief find best threshold for current splitting
     * @param values feature values
     * @param bestSplitInfo struct including best split information
     * @param e entropy before split
     * @param maxClassNo maximum class number
     */
    void findBestSplitThreshold (
            FeatureValuesUnsorted & values,
            SplitInfo & bestSplitInfo,
            const NICE::Vector & beta,
            const double & e,
            const int & maxClassNo );

    /**
     * @brief recursive building method
     * @param fp feature pool
     * @param examples all examples of the training
     * @param examples_selection indeces of selected example subset
     * @param distribution class distribution in current node
     * @param entropy current entropy
     * @param maxClassNo maximum class number
     * @param depth current depth
     * @return Pointer to root/parent node
     */
    DecisionNode *buildRecursive (
           const FeaturePool & fp,
           const Examples & examples,
           std::vector<int> & examples_selection,
           FullVector & distribution,
           double entropy,
           int maxClassNo,
           int depth,
           double curLambda );

    /**
     * @brief compute entropy for left and right child
     * @param values feature values
     * @param threshold threshold for split
     * @param stat_left statistics for left child
     * @param stat_right statistics for right child
     * @param entropy_left entropy for left child
     * @param entropy_right entropy for right child
     * @param count_left amount of features in left child
     * @param count_right amount of features in right child
     * @param maxClassNo maximum class number
     * @return whether another split is possible or not
     */
    bool entropyLeftRight ( const FeatureValuesUnsorted & values,
           double threshold,
           double* stat_left,
           double* stat_right,
           double & entropy_left,
           double & entropy_right,
           double & count_left,
           double & count_right,
           int maxClassNo );

  public:

    /** simple constructor */
    DTBOblique ( const NICE::Config *conf,
                       std::string section = "DTBOblique" );

    /** simple destructor */
    virtual ~DTBOblique();

    /**
     * @brief initial building method
     * @param fp feature pool
     * @param examples all examples of the training
     * @param maxClassNo maximum class number
     * @return Pointer to root/parent node
     */
    DecisionNode *build ( const FeaturePool &fp,
                          const Examples &examples,
                          int maxClassNo );

};



} //namespace

#endif