include/dai/exactinf.h

   1 /*  This file is part of libDAI - http://www.libdai.org/
   2  *
   3  *  libDAI is licensed under the terms of the GNU General Public License version
   4  *  2, or (at your option) any later version. libDAI is distributed without any
   5  *  warranty. See the file COPYING for more details.
   6  *
   7  *  Copyright (C) 2006-2009  Joris Mooij  [joris dot mooij at libdai dot org]
   8  *  Copyright (C) 2006-2007  Radboud University Nijmegen, The Netherlands
   9  */
  10
  11
  12 /// \file
  13 /// \brief Defines ExactInf class, which can be used for exact inference on small factor graphs.
  14
  15
  16 #ifndef __defined_libdai_exactinf_h
  17 #define __defined_libdai_exactinf_h
  18
  19
  20 #include <dai/daialg.h>
  21 #include <dai/properties.h>
  22 #include <dai/factorgraph.h>
  23 #include <dai/enum.h>
  24
  25
  26 namespace dai {
  27
  28
  29 /// Exact inference algorithm using brute force enumeration (mainly useful for testing purposes)
  30 /** Inference is done simply by multiplying all factors together into one large factor,
  31  *  and then calculating marginals and partition sum from the product.
  32  *  \note This inference method can easily exhaust all available memory; in that case, one
  33  *  may try the JTree class instead.
  34  */
  35 class ExactInf : public DAIAlgFG {
  36     public:
  37         /// Parameters of this inference algorithm
  38         struct Properties {
  39             /// Verbosity
  40             size_t verbose;
  41         } props;
  42
  43         /// Name of this inference algorithm
  44         static const char *Name;
  45
  46     private:
  47         /// All single variable marginals
  48         std::vector<Factor> _beliefsV;
  49         /// All factor variable marginals
  50         std::vector<Factor> _beliefsF;
  51         /// Logarithm of partition sum
  52         Real                _logZ;
  53
  54     public:
  55     /// \name Constructors/destructors
  56     //@{
  57         /// Default constructor
  58         ExactInf() : DAIAlgFG(), props(), _beliefsV(), _beliefsF(), _logZ(0) {}
  59
  60         /// Construct from FactorGraph \a fg and PropertySet \a opts
  61         ExactInf( const FactorGraph &fg, const PropertySet &opts ) : DAIAlgFG(fg), props(), _beliefsV(), _beliefsF(), _logZ() {
  62             setProperties( opts );
  63             construct();
  64         }
  65     //@}
  66
  67     /// \name General InfAlg interface
  68     //@{
  69         virtual ExactInf* clone() const { return new ExactInf(*this); }
  70         virtual std::string identify() const;
  71         virtual Factor belief( const Var &n ) const { return beliefV( findVar( n ) ); }
  72         virtual Factor belief( const VarSet &ns ) const;
  73         virtual Factor beliefV( size_t i ) const { return _beliefsV[i]; }
  74         virtual Factor beliefF( size_t I ) const { return _beliefsF[I]; }
  75         virtual std::vector<Factor> beliefs() const;
  76         virtual Real logZ() const { return _logZ; }
  77         virtual void init();
  78         virtual void init( const VarSet &/*ns*/ ) { DAI_THROW(NOT_IMPLEMENTED); }
  79         virtual Real run();
  80         virtual Real maxDiff() const { DAI_THROW(NOT_IMPLEMENTED); return 0.0; }
  81         virtual size_t Iterations() const { DAI_THROW(NOT_IMPLEMENTED); return 0; }
  82         virtual void setProperties( const PropertySet &opts );
  83         virtual PropertySet getProperties() const;
  84         virtual std::string printProperties() const;
  85     //@}
  86
  87     /// \name Additional interface specific for JTree
  88     //@{
  89         /// Calculates marginal probability distribution for variables \a vs
  90         /** \note The complexity of this calculation is exponential in the number of variables.
  91          */
  92         Factor calcMarginal( const VarSet &vs ) const;
  93     //@}
  94
  95
  96     private:
  97         /// Helper function for constructors
  98         void construct();
  99 };
 100
 101
 102 } // end of namespace dai
 103
 104
 105 #endif