include/dai/decmap.h

   1 /*  This file is part of libDAI - http://www.libdai.org/
   2  *
   3  *  Copyright (c) 2006-2011, The libDAI authors. All rights reserved.
   4  *
   5  *  Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
   6  */
   7
   8
   9 /// \file
  10 /// \brief Defines class DecMAP, which constructs a MAP state by decimation
  11
  12
  13 #ifndef __defined_libdai_decmap_h
  14 #define __defined_libdai_decmap_h
  15
  16
  17 #include <dai/daialg.h>
  18
  19
  20 namespace dai {
  21
  22
  23 /// Approximate inference algorithm DecMAP, which constructs a MAP state by decimation
  24 /** Decimation involves repeating the following two steps until no free variables remain:
  25  *  - run an approximate inference algorithm,
  26  *  - clamp the factor with the lowest entropy to its most probable state
  27  */
  28 class DecMAP : public DAIAlgFG {
  29     private:
  30         /// Stores the final MAP state
  31         std::vector<size_t> _state;
  32         /// Stores the log probability of the MAP state
  33         Real _logp;
  34         /// Maximum difference encountered so far
  35         Real _maxdiff;
  36         /// Number of iterations needed
  37         size_t _iters;
  38
  39     public:
  40         /// Parameters for DecMAP
  41         struct Properties {
  42             /// Verbosity (amount of output sent to stderr)
  43             size_t verbose;
  44
  45             /// Complete or partial reinitialization of clamped subgraphs?
  46             bool reinit;
  47
  48             /// Name of the algorithm used to calculate the beliefs on clamped subgraphs
  49             std::string ianame;
  50
  51             /// Parameters for the algorithm used to calculate the beliefs on clamped subgraphs
  52             PropertySet iaopts;
  53         } props;
  54
  55     public:
  56         /// Default constructor
  57         DecMAP() : DAIAlgFG(), _state(), _logp(), _maxdiff(), _iters(), props() {}
  58
  59         /// Construct from FactorGraph \a fg and PropertySet \a opts
  60         /** \param fg Factor graph.
  61          *  \param opts Parameters @see Properties
  62          */
  63         DecMAP( const FactorGraph &fg, const PropertySet &opts );
  64
  65
  66     /// \name General InfAlg interface
  67     //@{
  68         virtual DecMAP* clone() const { return new DecMAP(*this); }
  69         virtual DecMAP* construct( const FactorGraph &fg, const PropertySet &opts ) const { return new DecMAP( fg, opts ); }
  70         virtual std::string name() const { return "DECMAP"; }
  71         virtual Factor belief( const Var &v ) const { return beliefV( findVar( v ) ); }
  72         virtual Factor belief( const VarSet &/*vs*/ ) const;
  73         virtual Factor beliefV( size_t i ) const;
  74         virtual Factor beliefF( size_t I ) const { return belief( factor(I).vars() ); }
  75         virtual std::vector<Factor> beliefs() const;
  76         virtual Real logZ() const { return _logp; }
  77         virtual std::vector<size_t> findMaximum() const { return _state; }
  78         virtual void init() { _maxdiff = 0.0; _iters = 0; }
  79         virtual void init( const VarSet &/*ns*/ ) { init(); }
  80         virtual Real run();
  81         virtual Real maxDiff() const { return _maxdiff; }
  82         virtual size_t Iterations() const { return _iters; }
  83         virtual void setProperties( const PropertySet &opts );
  84         virtual PropertySet getProperties() const;
  85         virtual std::string printProperties() const;
  86     //@}
  87 };
  88
  89
  90 } // end of namespace dai
  91
  92
  93 #endif