simpleBayesNetGenerator_tpl.h

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

#include <agrum/BN/generator/simpleBayesNetGenerator.h>
 
#include <agrum/base/core/utils_random.h>
 
namespace gum {
 
  // Use the SimpleCPTGenerator for generating the BNs CPT.
  template < GUM_Numeric GUM_SCALAR, template < typename > class ICPTGenerator >
  SimpleBayesNetGenerator< GUM_SCALAR, ICPTGenerator >::SimpleBayesNetGenerator(Size nbrNodes,
                                                                                Size maxArcs,
                                                                                Size maxModality) :
      IBayesNetGenerator< GUM_SCALAR, ICPTGenerator >(nbrNodes, maxArcs, maxModality) {
    GUM_CONSTRUCTOR(SimpleBayesNetGenerator);
  }
 
  // Use this constructor if you want to use a different policy for generating
  // CPT than the default one.
  // The cptGenerator will be erased when the destructor is called.
  // @param cptGenerator The policy used to generate CPT.
  /*template <GumScalar GUM_SCALAR, template<class> class ICPTGenerator>
  SimpleBayesNetGenerator<GUM_SCALAR,ICPTGenerator>::SimpleBayesNetGenerator(CPTGenerator*
  cptGenerator ,Size nbrNodes, float density, Size maxModality):
    IBayesNetGenerator<GUM_SCALAR,ICPTGenerator>(cptGenerator
  ,nbrNodes,density,maxModality) {
    GUM_CONSTRUCTOR ( SimpleBayesNetGenerator )
  }*/
 
  // Destructor.
  template < GUM_Numeric GUM_SCALAR, template < typename > class ICPTGenerator >
  SimpleBayesNetGenerator< GUM_SCALAR, ICPTGenerator >::~SimpleBayesNetGenerator() {
    GUM_DESTRUCTOR(SimpleBayesNetGenerator);
  }
 
  // Generates a Bayesian network using floats.
  // @param nbrNodes The number of nodes in the generated BN.
  // @param density The probability of adding an arc between two nodes.
  // @return A BNs randomly generated.
 
  template < GUM_Numeric GUM_SCALAR, template < typename > class ICPTGenerator >
  void SimpleBayesNetGenerator< GUM_SCALAR, ICPTGenerator >::generateBN(
      BayesNet< GUM_SCALAR >& bayesNet) {
    this->dag_.clear();
    this->dag_.addNodes(this->nbrNodes_);
 
    // We add arcs
    float density = (float)(this->maxArcs_ * 2) / (float)(this->nbrNodes_ * (this->nbrNodes_ - 1));
    for (Size i = 0; i < this->nbrNodes_; ++i)
      for (Size j = i + 1; j < this->nbrNodes_; ++j)
        if (randomProba() < density) this->dag_.addArc(i, j);
 
    // Adding arcs until we reach the maxArcs_ number
    while (this->dag_.sizeArcs() < this->maxArcs_) {
      Size i = randomValue(this->nbrNodes_);
      Size j = randomValue(this->nbrNodes_);
      if (i != j) {
        if (i > j) std::swap(i, j);
 
        if (!this->dag_.existsArc(i, j)) this->dag_.addArc(i, j);
      }
    }
 
    this->fromDAG(bayesNet);
    this->fillCPT(bayesNet);
  }
} /* namespace gum */