Chi2TestPolicy_tpl.h

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 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
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#pragma once
 

// =========================================================================
#include <agrum/FMDP/learning/core/testPolicy/Chi2TestPolicy.h>
 
// =========================================================================
 
 
namespace gum {
 
 
  // ##########################################################################
  //
  // ##########################################################################
 
  // ==========================================================================
  //
  // ==========================================================================
  template < typename GUM_SCALAR >
  void Chi2TestPolicy< GUM_SCALAR >::addObservation(Idx iattr, GUM_SCALAR ivalue) {
    ITestPolicy< GUM_SCALAR >::addObservation(iattr, ivalue);
    _conTab_.add(iattr, ivalue);
  }
 
  // ############################################################################
  // @name Test result
  // ############################################################################
 
  // ============================================================================
  // Computes the GStat of current variable according to the test
  // ============================================================================
  template < typename GUM_SCALAR >
  void Chi2TestPolicy< GUM_SCALAR >::computeScore() const {
    ITestPolicy< GUM_SCALAR >::computeScore();
    _chi2Score_ = 0;
    for (auto attrIter = _conTab_.attrABeginSafe(); attrIter != _conTab_.attrAEndSafe();
         ++attrIter) {
      double semiExpected = (double)(attrIter.val()) / (double)this->nbObservation();
      for (auto valIter = _conTab_.attrBBeginSafe(); valIter != _conTab_.attrBEndSafe();
           ++valIter) {
        double cell = (double)_conTab_.joint(attrIter.key(), valIter.key());
        if (cell < 5) continue;
        double expected = semiExpected * (double)(valIter.val());
 
        _chi2Score_ += std::pow(cell - expected, 2.0) / expected;
      }
    }
  }
 
  // ============================================================================
  // Returns the performance of current variable according to the test
  // ============================================================================
  template < typename GUM_SCALAR >
  double Chi2TestPolicy< GUM_SCALAR >::score() const {
    if (this->isModified_()) computeScore();
    double score = 1
                 - ChiSquare::probaChi2(_chi2Score_,
                                        (_conTab_.attrASize() - 1) * (_conTab_.attrBSize() - 1));
    return score;
  }
 
  // ============================================================================
  // Returns a second criterion to severe ties
  // ============================================================================
  template < typename GUM_SCALAR >
  double Chi2TestPolicy< GUM_SCALAR >::secondaryscore() const {
    if (this->isModified_()) computeScore();
    return _chi2Score_;
  }
 
  template < typename GUM_SCALAR >
  void Chi2TestPolicy< GUM_SCALAR >::add(const Chi2TestPolicy< GUM_SCALAR >& src) {
    ITestPolicy< GUM_SCALAR >::add(src);
    _conTab_ += src.ct();
  }
 
}   // End of namespace gum