gum::ExactBNdistance< GUM_SCALAR > Class Template Reference

ExactBNdistance computes exactly the KL divergence betweens 2 BNs. More...

#include <exactBNdistance.h>

Inheritance diagram for gum::ExactBNdistance< GUM_SCALAR >:

Collaboration diagram for gum::ExactBNdistance< GUM_SCALAR >:

Public Member Functions
	ExactBNdistance (const IBayesNet< GUM_SCALAR > &P, const IBayesNet< GUM_SCALAR > &Q)
	constructor must give 2 BNs More...
	ExactBNdistance (const BNdistance< GUM_SCALAR > &kl)
	copy constructor More...
virtual	~ExactBNdistance ()
	destructor More...
Complexity	difficulty () const
	return KL::Complexity::Heavy,KL::Complexity::Difficult,KL::Complexity::Correct depending on the BNs __p and __q More...
Accessors to results. The first call do the computations. The
others do not.
double	klPQ ()
Size	errorPQ ()
double	klQP ()
Size	errorQP ()
double	hellinger ()
double	bhattacharya ()
double	jsd ()
const IBayesNet< GUM_SCALAR > &	p () const
const IBayesNet< GUM_SCALAR > &	q () const

Protected Attributes
const IBayesNet< GUM_SCALAR > &	_p
const IBayesNet< GUM_SCALAR > &	_q
GUM_SCALAR	_klPQ
GUM_SCALAR	_klQP
GUM_SCALAR	_hellinger
GUM_SCALAR	_bhattacharya
GUM_SCALAR	_jsd
Size	_errorPQ
Size	_errorQP

Protected Member Functions
void	_computeKL () final
void	_process ()

Detailed Description

template<typename GUM_SCALAR>
class gum::ExactBNdistance< GUM_SCALAR >

ExactBNdistance computes exactly the KL divergence betweens 2 BNs.

ExactBNdistance should be used only if difficulty() gives an estimation ( KL_CORRECT ) of the needed time. KL.process() computes KL(P||Q) using klPQ() and KL(Q||P) using klQP(). The computations are made once. The second is for free :) ExactBNdistance allows as well to compute in the same time the Hellinger distance ( \( *\sqrt{\sum_i (\sqrt{p_i}-\sqrt{q_i})^2}\)) (Kokolakis and Nanopoulos, 2001).

It may happen that P*ln(P/Q) is not computable (Q=0 and P!=0). In such a case, KL keeps working but trace this error (errorPQ() and errorQP())? *

Warning

This ExactBNdistance should be use only if difficulty()==complexity::CORRECT or at most complexity::DIFFICULT ... snippets :

gum::KL base_kl(net1,net2);
if (base_kl.difficulty()!=KL::HEAVY) {
 gum::ExactBNdistance kl(base_kl);
 std::cout<<"KL net1||net2 :"<<kl.klPQ()<<std::endl;
} else {
 gum::GibbsKL kl(base_kl);
 std::cout<<"KL net1||net2 :"<<kl.klPQ()<<std::endl;
}

Definition at line 70 of file exactBNdistance.h.

Constructor & Destructor Documentation

ExactBNdistance() [1/2]

template<typename GUM_SCALAR >

gum::ExactBNdistance< GUM_SCALAR >::ExactBNdistance	(	const IBayesNet< GUM_SCALAR > &	P,
		const IBayesNet< GUM_SCALAR > &	Q
	)

constructor must give 2 BNs

Exceptions

gum::OperationNotAllowed

if the 2 BNs have not the same domainSize or compatible node sets.

Definition at line 37 of file exactBNdistance_tpl.h.

                                                                         :
      BNdistance< GUM_SCALAR >(P, Q) {
    GUM_CONSTRUCTOR(ExactBNdistance);
  }

ExactBNdistance() [2/2]

template<typename GUM_SCALAR >

gum::ExactBNdistance< GUM_SCALAR >::ExactBNdistance ( const BNdistance< GUM_SCALAR > &  kl )

explicit

copy constructor

Definition at line 44 of file exactBNdistance_tpl.h.

                                         :
      BNdistance< GUM_SCALAR >(kl) {
    GUM_CONSTRUCTOR(ExactBNdistance);
  }

~ExactBNdistance()

template<typename GUM_SCALAR >

gum::ExactBNdistance< GUM_SCALAR >::~ExactBNdistance ( )

virtual

destructor

Definition at line 51 of file exactBNdistance_tpl.h.

                                                  {
    GUM_DESTRUCTOR(ExactBNdistance);
  }

Member Function Documentation

_computeKL()

template<typename GUM_SCALAR >

void gum::ExactBNdistance< GUM_SCALAR >::_computeKL ( )

finalprotectedvirtual

Reimplemented from gum::BNdistance< GUM_SCALAR >.

Definition at line 56 of file exactBNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_bhattacharya, gum::BNdistance< GUM_SCALAR >::_errorPQ, gum::BNdistance< GUM_SCALAR >::_errorQP, gum::BNdistance< GUM_SCALAR >::_hellinger, gum::BNdistance< GUM_SCALAR >::_jsd, gum::BNdistance< GUM_SCALAR >::_klPQ, gum::BNdistance< GUM_SCALAR >::_klQP, gum::BNdistance< GUM_SCALAR >::_p, gum::BNdistance< GUM_SCALAR >::_q, and gum::HashTable< Key, Val, Alloc >::insert().

                                                 {
    _klPQ = _klQP = _hellinger = _bhattacharya = _jsd = (GUM_SCALAR)0.0;
    _errorPQ = _errorQP = 0;

    auto Ip = _p.completeInstantiation();
    auto Iq = _q.completeInstantiation();

    // map between _p variables and _q variables (using name of vars)
    HashTable< const DiscreteVariable*, const DiscreteVariable* > map;

    for (Idx ite = 0; ite < Ip.nbrDim(); ++ite) {
      map.insert(&Ip.variable(ite), &_q.variableFromName(Ip.variable(ite).name()));
    }
    GUM_SCALAR pp, pq, pmid, lpp, lpq, lpmid;
    for (Ip.setFirst(); !Ip.end(); ++Ip) {
      Iq.setValsFrom(map, Ip);
      pp = _p.jointProbability(Ip);
      pq = _q.jointProbability(Iq);
      pmid = (pp + pq) / 2.0;
      lpmid = lpq = lpp = (GUM_SCALAR)0.0;
      if (pmid != (GUM_SCALAR)0.0) lpmid = log2(pmid);
      if (pp != (GUM_SCALAR)0.0) lpp = log2(pp);
      if (pq != (GUM_SCALAR)0.0) lpq = log2(pq);


      _hellinger += std::pow(std::sqrt(pp) - std::sqrt(pq), 2);
      _bhattacharya += std::sqrt(pp * pq);

      if (pp != (GUM_SCALAR)0.0) {
        if (pq != (GUM_SCALAR)0.0) {
          _klPQ -= pp * (lpq - lpp);   // log2(pq / pp);
        } else {
          _errorPQ++;
        }
      }

      if (pq != (GUM_SCALAR)0.0) {
        if (pp != (GUM_SCALAR)0.0) {
          _klQP -= pq * (lpp - lpq);   // log2(pp / pq);
        } else {
          _errorQP++;
        }
      }
      if (pmid != (GUM_SCALAR)0.0) {
        _jsd +=
           pp * lpp + pq * lpq
           - (pp + pq) * lpmid;   // pp* log2(pp / pmid) + pq * log2(pq / pmid);
      }
    }
    _jsd /= 2.0;
    _hellinger = std::sqrt(_hellinger);
    _bhattacharya = -std::log(_bhattacharya);
  }

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_process()

template<typename GUM_SCALAR >

void gum::BNdistance< GUM_SCALAR >::_process ( )

protectedinherited

Definition at line 178 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::__done, and gum::BNdistance< GUM_SCALAR >::_computeKL().

Referenced by gum::BNdistance< GUM_SCALAR >::bhattacharya(), gum::BNdistance< GUM_SCALAR >::errorPQ(), gum::BNdistance< GUM_SCALAR >::errorQP(), gum::BNdistance< GUM_SCALAR >::hellinger(), gum::BNdistance< GUM_SCALAR >::jsd(), gum::BNdistance< GUM_SCALAR >::klPQ(), and gum::BNdistance< GUM_SCALAR >::klQP().

                                          {
    if (!__done) {
      _computeKL();
      __done = true;
    }
  }

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bhattacharya()

template<typename GUM_SCALAR >

INLINE double gum::BNdistance< GUM_SCALAR >::bhattacharya ( )

inherited

Returns

Bhattacharya distance (

See also

http://en.wikipedia.org/wiki/Bhattacharya_distance)

Definition at line 93 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_bhattacharya, and gum::BNdistance< GUM_SCALAR >::_process().

                                                       {
    _process();
    return _bhattacharya;
  }

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difficulty()

template<typename GUM_SCALAR >

Complexity gum::BNdistance< GUM_SCALAR >::difficulty ( ) const

inherited

return KL::Complexity::Heavy,KL::Complexity::Difficult,KL::Complexity::Correct depending on the BNs __p and __q

Definition at line 70 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::__difficulty.

                                                        {
    return __difficulty;
  }

errorPQ()

template<typename GUM_SCALAR >

INLINE Size gum::BNdistance< GUM_SCALAR >::errorPQ ( )

inherited

Returns

the number of errors while processing divergence KL(P||Q)

Definition at line 105 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_errorPQ, and gum::BNdistance< GUM_SCALAR >::_process().

                                                {
    _process();
    return _errorPQ;
  }

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errorQP()

template<typename GUM_SCALAR >

INLINE Size gum::BNdistance< GUM_SCALAR >::errorQP ( )

inherited

Returns

the number of errors while processing divergence KL(Q||P)

Definition at line 111 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_errorQP, and gum::BNdistance< GUM_SCALAR >::_process().

                                                {
    _process();
    return _errorQP;
  }

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hellinger()

template<typename GUM_SCALAR >

INLINE double gum::BNdistance< GUM_SCALAR >::hellinger ( )

inherited

Returns

hellinger distance (

See also

http://en.wikipedia.org/wiki/Hellinger_distance)

Definition at line 87 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_hellinger, and gum::BNdistance< GUM_SCALAR >::_process().

                                                    {
    _process();
    return _hellinger;
  }

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jsd()

template<typename GUM_SCALAR >

INLINE double gum::BNdistance< GUM_SCALAR >::jsd ( )

inherited

Returns

Jensen-Shannon divergence(

See also

https://en.wikipedia.org/wiki/Jensen%E2%80%93Shannon_divergence)

Definition at line 99 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_jsd, and gum::BNdistance< GUM_SCALAR >::_process().

                                              {
    _process();
    return _jsd;
  }

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klPQ()

template<typename GUM_SCALAR >

INLINE double gum::BNdistance< GUM_SCALAR >::klPQ ( )

inherited

Returns

divergence KL(P||Q)

Definition at line 75 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_klPQ, and gum::BNdistance< GUM_SCALAR >::_process().

                                               {
    _process();
    return _klPQ;
  }

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klQP()

template<typename GUM_SCALAR >

INLINE double gum::BNdistance< GUM_SCALAR >::klQP ( )

inherited

Returns

divergence KL(Q||P)

Definition at line 81 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_klQP, and gum::BNdistance< GUM_SCALAR >::_process().

                                               {
    _process();
    return _klQP;
  }

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p()

template<typename GUM_SCALAR >

INLINE const IBayesNet< GUM_SCALAR > & gum::BNdistance< GUM_SCALAR >::p ( ) const

inherited

Returns

p

Definition at line 117 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_p.

                                                                          {
    return _p;
  }

q()

template<typename GUM_SCALAR >

INLINE const IBayesNet< GUM_SCALAR > & gum::BNdistance< GUM_SCALAR >::q ( ) const

inherited

Returns

q

Definition at line 122 of file BNdistance_tpl.h.

References gum::BNdistance< GUM_SCALAR >::_q.

                                                                          {
    return _q;
  }

Member Data Documentation

_bhattacharya

template<typename GUM_SCALAR>

GUM_SCALAR gum::BNdistance< GUM_SCALAR >::_bhattacharya

protectedinherited

Definition at line 142 of file BNdistance.h.

Referenced by gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::bhattacharya().

_errorPQ

template<typename GUM_SCALAR>

Size gum::BNdistance< GUM_SCALAR >::_errorPQ

protectedinherited

Definition at line 145 of file BNdistance.h.

Referenced by gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::errorPQ().

_errorQP

template<typename GUM_SCALAR>

Size gum::BNdistance< GUM_SCALAR >::_errorQP

protectedinherited

Definition at line 146 of file BNdistance.h.

Referenced by gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::errorQP().

_hellinger

template<typename GUM_SCALAR>

GUM_SCALAR gum::BNdistance< GUM_SCALAR >::_hellinger

protectedinherited

Definition at line 141 of file BNdistance.h.

Referenced by gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::hellinger().

_jsd

template<typename GUM_SCALAR>

GUM_SCALAR gum::BNdistance< GUM_SCALAR >::_jsd

protectedinherited

Definition at line 143 of file BNdistance.h.

Referenced by gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::jsd().

_klPQ

template<typename GUM_SCALAR>

GUM_SCALAR gum::BNdistance< GUM_SCALAR >::_klPQ

protectedinherited

Definition at line 139 of file BNdistance.h.

Referenced by gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::klPQ().

_klQP

template<typename GUM_SCALAR>

GUM_SCALAR gum::BNdistance< GUM_SCALAR >::_klQP

protectedinherited

Definition at line 140 of file BNdistance.h.

Referenced by gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::klQP().

_p

template<typename GUM_SCALAR>

const IBayesNet< GUM_SCALAR >& gum::BNdistance< GUM_SCALAR >::_p

protectedinherited

Definition at line 136 of file BNdistance.h.

Referenced by gum::BNdistance< GUM_SCALAR >::__checkCompatibility(), gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), gum::BNdistance< GUM_SCALAR >::BNdistance(), and gum::BNdistance< GUM_SCALAR >::p().

_q

template<typename GUM_SCALAR>

const IBayesNet< GUM_SCALAR >& gum::BNdistance< GUM_SCALAR >::_q

protectedinherited

Definition at line 137 of file BNdistance.h.

Referenced by gum::BNdistance< GUM_SCALAR >::__checkCompatibility(), gum::ExactBNdistance< GUM_SCALAR >::_computeKL(), gum::GibbsBNdistance< GUM_SCALAR >::_computeKL(), and gum::BNdistance< GUM_SCALAR >::q().

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The documentation for this class was generated from the following files:

• agrum/BN/algorithms/divergence/exactBNdistance.h
• agrum/BN/algorithms/divergence/exactBNdistance_tpl.h