VariableIndex.h

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/* ----------------------------------------------------------------------------

 * 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/inference/Key.h>
#include <gtsam/base/FastMap.h>
#include <gtsam/base/FastVector.h>
#include <gtsam/dllexport.h>

#include <boost/optional/optional.hpp>
#include <boost/smart_ptr/shared_ptr.hpp>

#include <cassert>
#include <stdexcept>

namespace gtsam {

class GTSAM_EXPORT VariableIndex {
public:

  typedef boost::shared_ptr<VariableIndex> shared_ptr;
  typedef FastVector<size_t> Factors;
  typedef Factors::iterator Factor_iterator;
  typedef Factors::const_iterator Factor_const_iterator;

protected:
  typedef FastMap<Key,Factors> KeyMap;
  KeyMap index_;
  size_t nFactors_; // Number of factors in the original factor graph.
  size_t nEntries_; // Sum of involved variable counts of each factor.

public:
  typedef KeyMap::const_iterator const_iterator;
  typedef KeyMap::const_iterator iterator;
  typedef KeyMap::value_type value_type;

public:


  VariableIndex() : nFactors_(0), nEntries_(0) {}

  template<class FG>
  VariableIndex(const FG& factorGraph) : nFactors_(0), nEntries_(0) { augment(factorGraph); }


  size_t size() const { return index_.size(); }

  size_t nFactors() const { return nFactors_; }

  size_t nEntries() const { return nEntries_; }

  const Factors& operator[](Key variable) const {
    KeyMap::const_iterator item = index_.find(variable);
    if(item == index_.end())
      throw std::invalid_argument("Requested non-existent variable from VariableIndex");
    else
    return item->second;
  }


  bool equals(const VariableIndex& other, double tol=0.0) const;

  void print(const std::string& str = "VariableIndex: ",
      const KeyFormatter& keyFormatter = DefaultKeyFormatter) const;

  void outputMetisFormat(std::ostream& os) const;



  template<class FG>
  void augment(const FG& factors, boost::optional<const FastVector<size_t>&> newFactorIndices = boost::none);

  template<typename ITERATOR, class FG>
  void remove(ITERATOR firstFactor, ITERATOR lastFactor, const FG& factors);

  template<typename ITERATOR>
  void removeUnusedVariables(ITERATOR firstKey, ITERATOR lastKey);

  const_iterator begin() const { return index_.begin(); }

  const_iterator end() const { return index_.end(); }

  const_iterator find(Key key) const { return index_.find(key); }

protected:
  Factor_iterator factorsBegin(Key variable) { return internalAt(variable).begin(); }
  Factor_iterator factorsEnd(Key variable) { return internalAt(variable).end(); }

  Factor_const_iterator factorsBegin(Key variable) const { return internalAt(variable).begin(); }
  Factor_const_iterator factorsEnd(Key variable) const { return internalAt(variable).end(); }

  const Factors& internalAt(Key variable) const {
    const KeyMap::const_iterator item = index_.find(variable);
    assert(item != index_.end());
    return item->second; }

  Factors& internalAt(Key variable) {
    const KeyMap::iterator item = index_.find(variable);
    assert(item != index_.end());
    return item->second; }

};

template<>
struct traits<VariableIndex> : public Testable<VariableIndex> {
};

} //\ namespace gtsam

#include <gtsam/inference/VariableIndex-inl.h>