include/dai/evidence.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) 2009  Charles Vaske  [cvaske at soe dot ucsc dot edu]
   8  *  Copyright (C) 2009  University of California, Santa Cruz
   9  */
  10
  11
  12 /// \file
  13 /// \brief Defines classes Evidence and Observation
  14 /// \todo Describe tabular data file format
  15
  16
  17 #ifndef __defined_libdai_evidence_h
  18 #define __defined_libdai_evidence_h
  19
  20
  21 #include <istream>
  22 #include <dai/daialg.h>
  23
  24
  25 namespace dai {
  26
  27
  28 /// Stores observed values of a subset of variables
  29 class Observation {
  30     private:
  31         /// Used to store the state of some variables
  32         std::map<Var, size_t> _obs;
  33
  34     public:
  35         /// Default constructor
  36         Observation() : _obs() {}
  37
  38         /// Get all observations
  39         const std::map<Var, size_t>& observations() const { return _obs; }
  40
  41         /// Add an observation
  42         void addObservation( Var node, size_t setting );
  43
  44         /// Clamp variables in the graphical model to their observed values
  45         void applyEvidence( InfAlg& alg ) const;
  46 };
  47
  48
  49 /// Stores multiple joint observations of sets of variables.
  50 /** The Evidence class stores multiple samples, where each sample is the joint
  51  *  observation of the states of some variables.
  52  */
  53 class Evidence {
  54     private:
  55         /// Each sample is the joint observation of the states of some variables
  56         std::vector<Observation> _samples;
  57
  58     public:
  59         /// Default constructor
  60         Evidence() : _samples() {}
  61
  62         /// Construct from existing samples
  63         Evidence( std::vector<Observation> &samples ) : _samples(samples) {}
  64
  65         /// Read in tabular data from a stream.
  66         /** Each line contains one sample, and the first line is a header line with names.
  67          */
  68         void addEvidenceTabFile( std::istream& is, std::map<std::string, Var> &varMap );
  69
  70         /// Read in tabular data from a stream.
  71         /** Each line contains one sample, and the first line is a header line with
  72          *  variable labels which should correspond with a subset of the variables in fg.
  73          */
  74         void addEvidenceTabFile( std::istream& is, FactorGraph& fg );
  75
  76         /// Returns number of stored samples
  77         size_t nrSamples() const { return _samples.size(); }
  78
  79         /// @name Iterator interface
  80         //@{
  81         /// Iterator over the elements
  82         typedef std::vector<Observation>::iterator iterator;
  83         /// Constant iterator over the elements
  84         typedef std::vector<Observation>::const_iterator const_iterator;
  85
  86         /// Returns iterator that points to the first element
  87         iterator begin() { return _samples.begin(); }
  88         /// Returns constant iterator that points to the first element
  89         const_iterator begin() const { return _samples.begin(); }
  90         /// Returns iterator that points beyond the last element
  91         iterator end() { return _samples.end(); }
  92         /// Returns constant iterator that points beyond the last element
  93         const_iterator end() const { return _samples.end(); }
  94         //@}
  95 };
  96
  97
  98 } // end of namespace dai
  99
 100
 101 #endif