-/* Copyright (C) 2006-2008 Joris Mooij [j dot mooij at science dot ru dot nl]
+/* Copyright (C) 2006-2008 Joris Mooij [joris dot mooij at tuebingen dot mpg dot de]
+ Radboud University Nijmegen, The Netherlands /
+ Max Planck Institute for Biological Cybernetics, Germany
+
Copyright (C) 2002 Martijn Leisink [martijn@mbfys.kun.nl]
Radboud University Nijmegen, The Netherlands
-
+
This file is part of libDAI.
libDAI is free software; you can redistribute it and/or modify
*/
+/// \file
+/// \brief Defines TFactor<T> and Factor classes
+
+
#ifndef __defined_libdai_factor_h
#define __defined_libdai_factor_h
namespace dai {
-template<typename T> class TFactor;
-typedef TFactor<Real> Factor;
-
-
-// predefine friends
-template<typename T> Real dist( const TFactor<T> & x, const TFactor<T> & y, Prob::DistType dt );
-template<typename T> Real KL_dist( const TFactor<T> & p, const TFactor<T> & q );
-template<typename T> Real MutualInfo( const TFactor<T> & p );
-template<typename T> TFactor<T> max( const TFactor<T> & P, const TFactor<T> & Q );
-template<typename T> TFactor<T> min( const TFactor<T> & P, const TFactor<T> & Q );
-template<typename T> std::ostream& operator<< (std::ostream& os, const TFactor<T>& P);
-
-
-// T should be castable from and to double
+/// Represents a (probability) factor.
+/** Mathematically, a \e factor is a function mapping joint states of some
+ * variables to the nonnegative real numbers.
+ * More formally, denoting a discrete variable with label \f$l\f$ by
+ * \f$x_l\f$ and its state space by \f$X_l = \{0,1,\dots,S_l-1\}\f$,
+ * then a factor depending on the variables \f$\{x_l\}_{l\in L}\f$ is
+ * a function \f$f_L : \prod_{l\in L} X_l \to [0,\infty)\f$.
+ *
+ * In libDAI, a factor is represented by a TFactor<\a T> object, which has two
+ * components:
+ * \arg a VarSet, corresponding with the set of variables \f$\{x_l\}_{l\in L}\f$
+ * that the factor depends on;
+ * \arg a TProb<\a T>, a vector containing the value of the factor for each possible
+ * joint state of the variables.
+ *
+ * The factor values are stored in the entries of the TProb<\a T> in a particular
+ * ordering, which is defined by the one-to-one correspondence of a joint state
+ * in \f$\prod_{l\in L} X_l\f$ with a linear index in
+ * \f$\{0,1,\dots,\prod_{l\in L} S_l-1\}\f$ according to the mapping \f$\sigma\f$
+ * induced by VarSet::calcState(const std::map<Var,size_t> &).
+ *
+ * \tparam T Should be a scalar that is castable from and to double and should support elementary arithmetic operations.
+ * \todo Define a better fileformat for .fg files (maybe using XML)?
+ * \todo Add support for sparse factors.
+ */
template <typename T> class TFactor {
- protected:
+ private:
VarSet _vs;
TProb<T> _p;
public:
- // Construct Factor with empty VarSet but nonempty _p
+ /// Iterator over factor entries
+ typedef typename TProb<T>::iterator iterator;
+
+ /// Const iterator over factor entries
+ typedef typename TProb<T>::const_iterator const_iterator;
+
+ /// Constructs TFactor depending on no variables, with value p
TFactor ( Real p = 1.0 ) : _vs(), _p(1,p) {}
- // Construct Factor from VarSet
- TFactor( const VarSet& ns ) : _vs(ns), _p(_vs.states()) {}
+ /// Constructs TFactor depending on variables in ns, with uniform distribution
+ TFactor( const VarSet& ns ) : _vs(ns), _p(_vs.nrStates()) {}
- // Construct Factor from VarSet and initial value
- TFactor( const VarSet& ns, Real p ) : _vs(ns), _p(_vs.states(),p) {}
+ /// Constructs TFactor depending on variables in ns, with all values set to p
+ TFactor( const VarSet& ns, Real p ) : _vs(ns), _p(_vs.nrStates(),p) {}
- // Construct Factor from VarSet and initial array
- TFactor( const VarSet& ns, const Real* p ) : _vs(ns), _p(_vs.states(),p) {}
-
- // Construct Factor from VarSet and TProb<T>
+ /// Constructs TFactor depending on variables in ns, copying the values from the range starting at begin
+ /** \param ns contains the variables that the new TFactor should depend on.
+ * \tparam Iterator Iterates over instances of type T; should support addition of size_t.
+ * \param begin Points to first element to be added.
+ */
+ template<typename TIterator>
+ TFactor( const VarSet& ns, TIterator begin ) : _vs(ns), _p(begin, begin + _vs.nrStates(), _vs.nrStates()) {}
+
+ /// Constructs TFactor depending on variables in ns, with values set to the TProb p
TFactor( const VarSet& ns, const TProb<T>& p ) : _vs(ns), _p(p) {
#ifdef DAI_DEBUG
- assert( _vs.states() == _p.size() );
+ assert( _vs.nrStates() == _p.size() );
#endif
}
- // Construct Factor from Var
+ /// Constructs TFactor depending on the variable n, with uniform distribution
TFactor( const Var& n ) : _vs(n), _p(n.states()) {}
- // Copy constructor
- TFactor( const TFactor<T> &x ) : _vs(x._vs), _p(x._p) {}
-
- // Assignment operator
- TFactor<T> & operator= (const TFactor<T> &x) {
- if( this != &x ) {
- _vs = x._vs;
- _p = x._p;
- }
- return *this;
- }
-
+ /// Returns const reference to value vector
const TProb<T> & p() const { return _p; }
+ /// Returns reference to value vector
TProb<T> & p() { return _p; }
+
+ /// Returns const reference to variable set
const VarSet & vars() const { return _vs; }
- size_t states() const {
-#ifdef DAI_DEBUG
- assert( _vs.states() == _p.size() );
-#endif
- return _p.size();
- }
+ /// Returns the number of possible joint states of the variables
+ /** \note This is equal to the length of the value vector.
+ */
+ size_t states() const { return _p.size(); }
+
+ /// Returns a copy of the i'th entry of the value vector
T operator[] (size_t i) const { return _p[i]; }
+
+ /// Returns a reference to the i'th entry of the value vector
T& operator[] (size_t i) { return _p[i]; }
- TFactor<T> & fill (T p)
- { _p.fill( p ); return(*this); }
- TFactor<T> & randomize ()
- { _p.randomize(); return(*this); }
- TFactor<T> operator* (T x) const {
- Factor result = *this;
- result.p() *= x;
- return result;
- }
- TFactor<T>& operator*= (T x) {
- _p *= x;
+
+ /// Returns iterator pointing to first entry
+ iterator begin() { return _p.begin(); }
+ /// Returns const iterator pointing to first entry
+ const_iterator begin() const { return _p.begin(); }
+ /// Returns iterator pointing beyond last entry
+ iterator end() { return _p.end(); }
+ /// Returns const iterator pointing beyond last entry
+ const_iterator end() const { return _p.end(); }
+
+ /// Sets all values to p
+ TFactor<T> & fill (T p) { _p.fill( p ); return(*this); }
+
+ /// Draws all values i.i.d. from a uniform distribution on [0,1)
+ TFactor<T> & randomize () { _p.randomize(); return(*this); }
+
+
+ /// Multiplies *this with scalar t
+ TFactor<T>& operator*= (T t) {
+ _p *= t;
return *this;
}
- TFactor<T> operator/ (T x) const {
- Factor result = *this;
- result.p() /= x;
- return result;
- }
- TFactor<T>& operator/= (T x) {
- _p /= x;
+
+ /// Divides *this by scalar t
+ TFactor<T>& operator/= (T t) {
+ _p /= t;
return *this;
}
- TFactor<T> operator* (const TFactor<T>& Q) const;
- TFactor<T> operator/ (const TFactor<T>& Q) const;
- TFactor<T>& operator*= (const TFactor<T>& Q) { return( *this = (*this * Q) ); }
- TFactor<T>& operator/= (const TFactor<T>& Q) { return( *this = (*this / Q) ); }
- TFactor<T> operator+ (const TFactor<T>& Q) const {
-#ifdef DAI_DEBUG
- assert( Q._vs == _vs );
-#endif
- TFactor<T> sum(*this);
- sum._p += Q._p;
- return sum;
- }
- TFactor<T> operator- (const TFactor<T>& Q) const {
-#ifdef DAI_DEBUG
- assert( Q._vs == _vs );
-#endif
- TFactor<T> sum(*this);
- sum._p -= Q._p;
- return sum;
- }
- TFactor<T>& operator+= (const TFactor<T>& Q) {
-#ifdef DAI_DEBUG
- assert( Q._vs == _vs );
-#endif
- _p += Q._p;
+
+ /// Adds scalar t to *this
+ TFactor<T>& operator+= (T t) {
+ _p += t;
return *this;
}
- TFactor<T>& operator-= (const TFactor<T>& Q) {
-#ifdef DAI_DEBUG
- assert( Q._vs == _vs );
-#endif
- _p -= Q._p;
+
+ /// Subtracts scalar t from *this
+ TFactor<T>& operator-= (T t) {
+ _p -= t;
return *this;
}
- TFactor<T>& operator+= (T q) {
- _p += q;
- return *this;
+
+ /// Raises *this to the power a
+ TFactor<T>& operator^= (Real a) { _p ^= a; return *this; }
+
+
+ /// Returns product of *this with scalar t
+ TFactor<T> operator* (T t) const {
+ TFactor<T> result = *this;
+ result.p() *= t;
+ return result;
}
- TFactor<T>& operator-= (T q) {
- _p -= q;
- return *this;
+
+ /// Returns quotient of *this with scalar t
+ TFactor<T> operator/ (T t) const {
+ TFactor<T> result = *this;
+ result.p() /= t;
+ return result;
}
- TFactor<T> operator+ (T q) const {
+
+ /// Returns sum of *this and scalar t
+ TFactor<T> operator+ (T t) const {
TFactor<T> result(*this);
- result._p += q;
+ result._p += t;
return result;
}
- TFactor<T> operator- (T q) const {
+
+ /// Returns *this minus scalar t
+ TFactor<T> operator- (T t) const {
TFactor<T> result(*this);
- result._p -= q;
+ result._p -= t;
return result;
}
- TFactor<T> operator^ (Real a) const { TFactor<T> x; x._vs = _vs; x._p = _p^a; return x; }
- TFactor<T>& operator^= (Real a) { _p ^= a; return *this; }
+ /// Returns *this raised to the power a
+ TFactor<T> operator^ (Real a) const {
+ TFactor<T> x;
+ x._vs = _vs;
+ x._p = _p^a;
+ return x;
+ }
- TFactor<T>& makeZero( Real epsilon ) {
- _p.makeZero( epsilon );
+ /// Multiplies *this with the TFactor f
+ TFactor<T>& operator*= (const TFactor<T>& f) {
+ if( f._vs == _vs ) // optimize special case
+ _p *= f._p;
+ else
+ *this = (*this * f);
return *this;
}
- TFactor<T>& makePositive( Real epsilon ) {
- _p.makePositive( epsilon );
+ /// Divides *this by the TFactor f
+ TFactor<T>& operator/= (const TFactor<T>& f) {
+ if( f._vs == _vs ) // optimize special case
+ _p /= f._p;
+ else
+ *this = (*this / f);
return *this;
}
-
- TFactor<T> inverse() const {
- TFactor<T> inv;
- inv._vs = _vs;
- inv._p = _p.inverse(true); // FIXME
- return inv;
+
+ /// Returns product of *this with the TFactor f
+ /** The product of two factors is defined as follows: if
+ * \f$f : \prod_{l\in L} X_l \to [0,\infty)\f$ and \f$g : \prod_{m\in M} X_m \to [0,\infty)\f$, then
+ * \f[fg : \prod_{l\in L\cup M} X_l \to [0,\infty) : x \mapsto f(x_L) g(x_M).\f]
+ */
+ TFactor<T> operator* (const TFactor<T>& f) const;
+
+ /// Returns quotient of *this by the TFactor f
+ /** The quotient of two factors is defined as follows: if
+ * \f$f : \prod_{l\in L} X_l \to [0,\infty)\f$ and \f$g : \prod_{m\in M} X_m \to [0,\infty)\f$, then
+ * \f[\frac{f}{g} : \prod_{l\in L\cup M} X_l \to [0,\infty) : x \mapsto \frac{f(x_L)}{g(x_M)}.\f]
+ */
+ TFactor<T> operator/ (const TFactor<T>& f) const;
+
+ /// Adds the TFactor f to *this
+ /** \pre this->vars() == f.vars()
+ */
+ TFactor<T>& operator+= (const TFactor<T>& f) {
+#ifdef DAI_DEBUG
+ assert( f._vs == _vs );
+#endif
+ _p += f._p;
+ return *this;
+ }
+
+ /// Subtracts the TFactor f from *this
+ /** \pre this->vars() == f.vars()
+ */
+ TFactor<T>& operator-= (const TFactor<T>& f) {
+#ifdef DAI_DEBUG
+ assert( f._vs == _vs );
+#endif
+ _p -= f._p;
+ return *this;
}
- TFactor<T> divided_by( const TFactor<T>& denom ) const {
+ /// Returns sum of *this and the TFactor f
+ /** \pre this->vars() == f.vars()
+ */
+ TFactor<T> operator+ (const TFactor<T>& f) const {
#ifdef DAI_DEBUG
- assert( denom._vs == _vs );
+ assert( f._vs == _vs );
#endif
- TFactor<T> quot(*this);
- quot._p /= denom._p;
- return quot;
+ TFactor<T> sum(*this);
+ sum._p += f._p;
+ return sum;
}
- TFactor<T>& divide( const TFactor<T>& denom ) {
+ /// Returns *this minus the TFactor f
+ /** \pre this->vars() == f.vars()
+ */
+ TFactor<T> operator- (const TFactor<T>& f) const {
#ifdef DAI_DEBUG
- assert( denom._vs == _vs );
+ assert( f._vs == _vs );
#endif
- _p /= denom._p;
+ TFactor<T> sum(*this);
+ sum._p -= f._p;
+ return sum;
+ }
+
+
+ /// Sets all values that are smaller than epsilon to 0
+ TFactor<T>& makeZero( T epsilon ) {
+ _p.makeZero( epsilon );
+ return *this;
+ }
+
+ /// Sets all values that are smaller than epsilon to epsilon
+ TFactor<T>& makePositive( T epsilon ) {
+ _p.makePositive( epsilon );
return *this;
}
+
+ /// Returns pointwise inverse of *this.
+ /** If zero == true, uses 1 / 0 == 0; otherwise 1 / 0 == Inf.
+ */
+ TFactor<T> inverse(bool zero=true) const {
+ TFactor<T> inv;
+ inv._vs = _vs;
+ inv._p = _p.inverse(zero);
+ return inv;
+ }
+ /// Returns pointwise exp of *this
TFactor<T> exp() const {
TFactor<T> e;
e._vs = _vs;
return e;
}
+ /// Returns pointwise logarithm of *this
+ /** If zero==true, uses log(0)==0; otherwise, log(0)=-Inf.
+ */
+ TFactor<T> log(bool zero=false) const {
+ TFactor<T> l;
+ l._vs = _vs;
+ l._p = _p.log(zero);
+ return l;
+ }
+
+ /// Returns pointwise absolute value of *this
TFactor<T> abs() const {
TFactor<T> e;
e._vs = _vs;
return e;
}
- TFactor<T> log() const {
- TFactor<T> l;
- l._vs = _vs;
- l._p = _p.log();
- return l;
- }
-
- TFactor<T> log0() const {
- TFactor<T> l0;
- l0._vs = _vs;
- l0._p = _p.log0();
- return l0;
- }
+ /// Normalizes *this TFactor according to the specified norm
+ T normalize( typename Prob::NormType norm=Prob::NORMPROB ) { return _p.normalize( norm ); }
- T normalize( typename Prob::NormType norm = Prob::NORMPROB ) { return _p.normalize( norm ); }
- TFactor<T> normalized( typename Prob::NormType norm = Prob::NORMPROB ) const {
+ /// Returns a normalized copy of *this, according to the specified norm
+ TFactor<T> normalized( typename Prob::NormType norm=Prob::NORMPROB ) const {
TFactor<T> result;
result._vs = _vs;
result._p = _p.normalized( norm );
return result;
}
- // returns slice of this factor where the subset ns is in state ns_state
- Factor slice( const VarSet & ns, size_t ns_state ) const {
+ /// Returns a slice of this TFactor, where the subset ns is in state nsState
+ /** \pre \a ns sould be a subset of vars()
+ * \pre \a nsState < ns.states()
+ *
+ * The result is a TFactor that depends on the variables in this->vars() except those in \a ns,
+ * obtained by setting the variables in \a ns to the joint state specified by the linear index
+ * \a nsState. Formally, if *this corresponds with the factor \f$f : \prod_{l\in L} X_l \to [0,\infty)\f$,
+ * \f$M \subset L\f$ corresponds with \a ns and \a nsState corresponds with a mapping \f$s\f$ that
+ * maps a variable \f$x_m\f$ with \f$m\in M\f$ to its state \f$s(x_m) \in X_m\f$, then the slice
+ * returned corresponds with the factor \f$g : \prod_{l \in L \setminus M} X_l \to [0,\infty)\f$
+ * defined by \f$g(\{x_l\}_{l\in L \setminus M}) = f(\{x_l\}_{l\in L \setminus M}, \{s(x_m)\}_{m\in M})\f$.
+ */
+ TFactor<T> slice( const VarSet& ns, size_t nsState ) const {
assert( ns << _vs );
VarSet nsrem = _vs / ns;
- Factor result( nsrem, 0.0 );
+ TFactor<T> result( nsrem, T(0) );
// OPTIMIZE ME
IndexFor i_ns (ns, _vs);
IndexFor i_nsrem (nsrem, _vs);
for( size_t i = 0; i < states(); i++, ++i_ns, ++i_nsrem )
- if( (size_t)i_ns == ns_state )
+ if( (size_t)i_ns == nsState )
result._p[i_nsrem] = _p[i];
return result;
}
- // returns unnormalized marginal; ns should be a subset of vars()
- TFactor<T> partSum(const VarSet & ns) const;
- // returns (normalized by default) marginal; ns should be a subset of vars()
- TFactor<T> marginal(const VarSet & ns, bool normed = true) const { if(normed) return partSum(ns).normalized(); else return partSum(ns); }
- // sums out all variables except those in ns
- TFactor<T> notSum(const VarSet & ns) const { return partSum(vars() ^ ns); }
+ /// Returns marginal on ns, obtained by summing out all variables except those in ns, and normalizing the result if normed==true
+ TFactor<T> marginal(const VarSet & ns, bool normed=true) const;
- // embeds this factor in larger varset ns
+ /// Embeds this factor in a larger VarSet
+ /** \pre vars() should be a subset of ns
+ *
+ * If *this corresponds with \f$f : \prod_{l\in L} X_l \to [0,\infty)\f$ and \f$L \subset M\f$, then
+ * the embedded factor corresponds with \f$g : \prod_{m\in M} X_m \to [0,\infty) : x \mapsto f(x_L)\f$.
+ */
TFactor<T> embed(const VarSet & ns) const {
- VarSet vs = vars();
- assert( ns >> vs );
- if( vs == ns )
+ assert( ns >> _vs );
+ if( _vs == ns )
return *this;
else
- return (*this) * Factor(ns / vs, 1.0);
+ return (*this) * TFactor<T>(ns / _vs, (T)1);
}
+ /// Returns true if *this has NaN values
bool hasNaNs() const { return _p.hasNaNs(); }
+
+ /// Returns true if *this has negative values
bool hasNegatives() const { return _p.hasNegatives(); }
- T totalSum() const { return _p.totalSum(); }
+
+ /// Returns total sum of values
+ T sum() const { return _p.sum(); }
+
+ /// Returns maximum absolute value
T maxAbs() const { return _p.maxAbs(); }
- T maxVal() const { return _p.maxVal(); }
- T minVal() const { return _p.minVal(); }
+
+ /// Returns maximum value
+ T max() const { return _p.max(); }
+
+ /// Returns minimum value
+ T min() const { return _p.min(); }
+
+ /// Returns entropy of *this TFactor
Real entropy() const { return _p.entropy(); }
- T strength( const Var &i, const Var &j ) const;
- friend Real dist( const TFactor<T> & x, const TFactor<T> & y, Prob::DistType dt ) {
- if( x._vs.empty() || y._vs.empty() )
- return -1;
- else {
-#ifdef DAI_DEBUG
- assert( x._vs == y._vs );
-#endif
- return dist( x._p, y._p, dt );
- }
- }
- friend Real KL_dist <> (const TFactor<T> & p, const TFactor<T> & q);
- friend Real MutualInfo <> ( const TFactor<T> & P );
- template<class U> friend std::ostream& operator<< (std::ostream& os, const TFactor<U>& P);
+ /// Returns strength of *this TFactor (between variables i and j), as defined in eq. (52) of [\ref MoK07b]
+ T strength( const Var &i, const Var &j ) const;
};
-template<typename T> TFactor<T> TFactor<T>::partSum(const VarSet & ns) const {
-#ifdef DAI_DEBUG
- assert( ns << _vs );
-#endif
+template<typename T> TFactor<T> TFactor<T>::marginal(const VarSet & ns, bool normed) const {
+ VarSet res_ns = ns & _vs;
- TFactor<T> res( ns, 0.0 );
+ TFactor<T> res( res_ns, 0.0 );
- IndexFor i_res( ns, _vs );
+ IndexFor i_res( res_ns, _vs );
for( size_t i = 0; i < _p.size(); i++, ++i_res )
res._p[i_res] += _p[i];
- return res;
-}
-
+ if( normed )
+ res.normalize( Prob::NORMPROB );
-template<typename T> std::ostream& operator<< (std::ostream& os, const TFactor<T>& P) {
- os << "(" << P.vars() << " <";
- for( size_t i = 0; i < P._p.size(); i++ )
- os << P._p[i] << " ";
- os << ">)";
- return os;
+ return res;
}
-template<typename T> TFactor<T> TFactor<T>::operator* (const TFactor<T>& Q) const {
- TFactor<T> prod( _vs | Q._vs, 0.0 );
+template<typename T> TFactor<T> TFactor<T>::operator* (const TFactor<T>& f) const {
+ if( f._vs == _vs ) { // optimizate special case
+ TFactor<T> prod(*this);
+ prod._p *= f._p;
+ return prod;
+ } else {
+ TFactor<T> prod( _vs | f._vs, 0.0 );
- IndexFor i1(_vs, prod._vs);
- IndexFor i2(Q._vs, prod._vs);
+ IndexFor i1(_vs, prod._vs);
+ IndexFor i2(f._vs, prod._vs);
- for( size_t i = 0; i < prod._p.size(); i++, ++i1, ++i2 )
- prod._p[i] += _p[i1] * Q._p[i2];
+ for( size_t i = 0; i < prod._p.size(); i++, ++i1, ++i2 )
+ prod._p[i] += _p[i1] * f._p[i2];
- return prod;
+ return prod;
+ }
}
-template<typename T> TFactor<T> TFactor<T>::operator/ (const TFactor<T>& Q) const {
- TFactor<T> quot( _vs + Q._vs, 0.0 );
-
- IndexFor i1(_vs, quot._vs);
- IndexFor i2(Q._vs, quot._vs);
+template<typename T> TFactor<T> TFactor<T>::operator/ (const TFactor<T>& f) const {
+ if( f._vs == _vs ) { // optimizate special case
+ TFactor<T> quot(*this);
+ quot._p /= f._p;
+ return quot;
+ } else {
+ TFactor<T> quot( _vs | f._vs, 0.0 );
- for( size_t i = 0; i < quot._p.size(); i++, ++i1, ++i2 )
- quot._p[i] += _p[i1] / Q._p[i2];
+ IndexFor i1(_vs, quot._vs);
+ IndexFor i2(f._vs, quot._vs);
- return quot;
-}
+ for( size_t i = 0; i < quot._p.size(); i++, ++i1, ++i2 )
+ quot._p[i] += _p[i1] / f._p[i2];
-
-template<typename T> Real KL_dist(const TFactor<T> & P, const TFactor<T> & Q) {
- if( P._vs.empty() || Q._vs.empty() )
- return -1;
- else {
-#ifdef DAI_DEBUG
- assert( P._vs == Q._vs );
-#endif
- return KL_dist( P._p, Q._p );
+ return quot;
}
}
-// calculate mutual information of x_i and x_j where P.vars() = \{x_i,x_j\}
-template<typename T> Real MutualInfo(const TFactor<T> & P) {
- assert( P._vs.size() == 2 );
- VarSet::const_iterator it = P._vs.begin();
- Var i = *it; it++; Var j = *it;
- TFactor<T> projection = P.marginal(i) * P.marginal(j);
- return real( KL_dist( P.normalized(), projection ) );
-}
-
-
-template<typename T> TFactor<T> max( const TFactor<T> & P, const TFactor<T> & Q ) {
- assert( P._vs == Q._vs );
- return TFactor<T>( P._vs, min( P.p(), Q.p() ) );
-}
-
-template<typename T> TFactor<T> min( const TFactor<T> & P, const TFactor<T> & Q ) {
- assert( P._vs == Q._vs );
- return TFactor<T>( P._vs, max( P.p(), Q.p() ) );
-}
-
-// calculate N(psi, i, j)
template<typename T> T TFactor<T>::strength( const Var &i, const Var &j ) const {
#ifdef DAI_DEBUG
assert( _vs.contains( i ) );
bs = i.states();
else
as = j.states();
- T f1 = slice( ij, alpha1 * as + beta1 * bs ).p().divide( slice( ij, alpha2 * as + beta1 * bs ).p() ).maxVal();
- T f2 = slice( ij, alpha2 * as + beta2 * bs ).p().divide( slice( ij, alpha1 * as + beta2 * bs ).p() ).maxVal();
+ T f1 = slice( ij, alpha1 * as + beta1 * bs ).p().divide( slice( ij, alpha2 * as + beta1 * bs ).p() ).max();
+ T f2 = slice( ij, alpha2 * as + beta2 * bs ).p().divide( slice( ij, alpha1 * as + beta2 * bs ).p() ).max();
T f = f1 * f2;
if( f > max )
max = f;
}
-template<typename T> TFactor<T> RemoveFirstOrderInteractions( const TFactor<T> & psi ) {
- TFactor<T> result = psi;
+/// Writes a TFactor to an output stream
+/** \relates TFactor
+ */
+template<typename T> std::ostream& operator<< (std::ostream& os, const TFactor<T>& P) {
+ os << "(" << P.vars() << ", (";
+ for( size_t i = 0; i < P.states(); i++ )
+ os << (i == 0 ? "" : ", ") << P[i];
+ os << "))";
+ return os;
+}
+
- VarSet vars = psi.vars();
- for( size_t iter = 0; iter < 100; iter++ ) {
- for( VarSet::const_iterator n = vars.begin(); n != vars.end(); n++ )
- result = result * result.partSum(*n).inverse();
- result.normalize();
+/// Returns distance between two TFactors f and g, according to the distance measure dt
+/** \relates TFactor
+ * \pre f.vars() == g.vars()
+ */
+template<typename T> Real dist( const TFactor<T> &f, const TFactor<T> &g, Prob::DistType dt ) {
+ if( f.vars().empty() || g.vars().empty() )
+ return -1;
+ else {
+#ifdef DAI_DEBUG
+ assert( f.vars() == g.vars() );
+#endif
+ return dist( f.p(), g.p(), dt );
}
+}
- return result;
+
+/// Returns the pointwise maximum of two TFactors
+/** \relates TFactor
+ * \pre f.vars() == g.vars()
+ */
+template<typename T> TFactor<T> max( const TFactor<T> &f, const TFactor<T> &g ) {
+ assert( f._vs == g._vs );
+ return TFactor<T>( f._vs, min( f.p(), g.p() ) );
+}
+
+
+/// Returns the pointwise minimum of two TFactors
+/** \relates TFactor
+ * \pre f.vars() == g.vars()
+ */
+template<typename T> TFactor<T> min( const TFactor<T> &f, const TFactor<T> &g ) {
+ assert( f._vs == g._vs );
+ return TFactor<T>( f._vs, max( f.p(), g.p() ) );
+}
+
+
+/// Calculates the mutual information between the two variables that f depends on, under the distribution given by f
+/** \relates TFactor
+ * \pre f.vars().size() == 2
+ */
+template<typename T> Real MutualInfo(const TFactor<T> &f) {
+ assert( f.vars().size() == 2 );
+ VarSet::const_iterator it = f.vars().begin();
+ Var i = *it; it++; Var j = *it;
+ TFactor<T> projection = f.marginal(i) * f.marginal(j);
+ return real( dist( f.normalized(), projection, Prob::DISTKL ) );
}
+/// Represents a factor with values of type Real.
+typedef TFactor<Real> Factor;
+
+
} // end of namespace dai
projects / libdai.git / blobdiff