gtsam::VariableIndex Class Reference

Detailed Description

The VariableIndex class computes and stores the block column structure of a factor graph.

The factor graph stores a collection of factors, each of which involves a set of variables. In contrast, the VariableIndex is built from a factor graph prior to elimination, and stores the list of factors that involve each variable. This information is stored as a deque of lists of factor indices.

Standard Constructors
	VariableIndex ()
	Default constructor, creates an empty VariableIndex.
template<class FG >
	VariableIndex (const FG &factorGraph)
	Create a VariableIndex that computes and stores the block column structure of a factor graph.

Standard Interface
size_t	size () const
	The number of variable entries. This is equal to the number of unique variable Keys.
size_t	nFactors () const
	The number of factors in the original factor graph.
size_t	nEntries () const
	The number of nonzero blocks, i.e. the number of variable-factor entries.
const Factors &	operator[] (Key variable) const
	Access a list of factors by variable.

Testable
bool	equals (const VariableIndex &other, double tol=0.0) const
	Test for equality (for unit tests and debug assertions).
void	print (const std::string &str="VariableIndex: ", const KeyFormatter &keyFormatter=DefaultKeyFormatter) const
	Print the variable index (for unit tests and debugging).
void	outputMetisFormat (std::ostream &os) const
	Output dual hypergraph to Metis file format for use with hmetis In the dual graph, variables are hyperedges, factors are nodes.

Advanced Interface
template<class FG >
void	augment (const FG &factors, boost::optional< const FactorIndices & > newFactorIndices=boost::none)
	Augment the variable index with new factors. More...
template<typename ITERATOR , class FG >
void	remove (ITERATOR firstFactor, ITERATOR lastFactor, const FG &factors)
	Remove entries corresponding to the specified factors. More...
template<typename ITERATOR >
void	removeUnusedVariables (ITERATOR firstKey, ITERATOR lastKey)
	Remove unused empty variables (in debug mode verifies they are empty).
const_iterator	begin () const
	Iterator to the first variable entry.
const_iterator	end () const
	Iterator to the first variable entry.
const_iterator	find (Key key) const
	Find the iterator for the requested variable entry.
Factor_iterator	factorsBegin (Key variable)
Factor_iterator	factorsEnd (Key variable)
Factor_const_iterator	factorsBegin (Key variable) const
Factor_const_iterator	factorsEnd (Key variable) const
const Factors &	internalAt (Key variable) const
	Internal version of 'at' that asserts existence.
Factors &	internalAt (Key variable)
	Internal version of 'at' that asserts existence.

Public Types
typedef boost::shared_ptr< VariableIndex >	shared_ptr
typedef FactorIndices	Factors
typedef Factors::iterator	Factor_iterator
typedef Factors::const_iterator	Factor_const_iterator
typedef KeyMap::const_iterator	const_iterator
typedef KeyMap::const_iterator	iterator
typedef KeyMap::value_type	value_type

Protected Types
typedef FastMap< Key, Factors >	KeyMap

Protected Attributes
KeyMap	index_
size_t	nFactors_
size_t	nEntries_

Member Function Documentation

augment()

template<class FG >

void gtsam::VariableIndex::augment	(	const FG &	factors,
		boost::optional< const FactorIndices & >	newFactorIndices = boost::none
	)

Augment the variable index with new factors.

This can be used when solving problems incrementally.

remove()

template<typename ITERATOR , class FG >

void gtsam::VariableIndex::remove	(	ITERATOR	firstFactor,
		ITERATOR	lastFactor,
		const FG &	factors
	)

Remove entries corresponding to the specified factors.

NOTE: We intentionally do not decrement nFactors_ because the factor indices need to remain consistent. Removing factors from a factor graph does not shift the indices of other factors. Also, we keep nFactors_ one greater than the highest-numbered factor referenced in a VariableIndex.

Parameters

indices	The indices of the factors to remove, which must match factors
factors	The factors being removed, which must symbolically correspond exactly to the factors with the specified indices that were added.

---

The documentation for this class was generated from the following files:

• /Users/dellaert/git/gtsam/gtsam/inference/VariableIndex.h
• /Users/dellaert/git/gtsam/gtsam/inference/VariableIndex-inl.h
• /Users/dellaert/git/gtsam/gtsam/inference/VariableIndex.cpp