DiscreteMarginals.h

Go to the documentation of this file.

/* ----------------------------------------------------------------------------
 
 * GTSAM Copyright 2010, Georgia Tech Research Corporation,
 * Atlanta, Georgia 30332-0415
 * All Rights Reserved
 * Authors: Frank Dellaert, et al. (see THANKS for the full author list)
 
 * See LICENSE for the license information
 
 * -------------------------------------------------------------------------- */
 
#pragma once
 
#include <gtsam/discrete/DiscreteFactorGraph.h>
#include <gtsam/discrete/DiscreteBayesTree.h>
#include <gtsam/base/Vector.h>
 
namespace gtsam {
 
  class DiscreteMarginals {
 
  protected:
 
    DiscreteBayesTree::shared_ptr bayesTree_;
 
  public:
 
  DiscreteMarginals(const DiscreteFactorGraph& graph) {
    bayesTree_ = graph.eliminateMultifrontal();
  }
 
  DiscreteFactor::shared_ptr operator()(Key variable) const {
    // Compute marginal
    DiscreteFactor::shared_ptr marginalFactor;
    marginalFactor = bayesTree_->marginalFactor(variable, &EliminateDiscrete);
    return marginalFactor;
  }
 
  Vector marginalProbabilities(const DiscreteKey& key) const {
    // Compute marginal
    DiscreteFactor::shared_ptr marginalFactor;
    marginalFactor = bayesTree_->marginalFactor(key.first, &EliminateDiscrete);
 
    //Create result
    Vector vResult(key.second);
    for (size_t state = 0; state < key.second ; ++ state) {
      DiscreteFactor::Values values;
      values[key.first] = state;
      vResult(state) = (*marginalFactor)(values);
    }
    return vResult;
  }
 
  };
 
} /* namespace gtsam */