Detailed Description

An efficient algorithm for finding neighbors.

#include <GNeighborFinder.h>

Inheritance diagram for GClasses::GKdTree:

Public Member Functions
	GKdTree (const GMatrix pData, GDistanceMetric pMetric=NULL, bool ownMetric=false)

virtual	~GKdTree ()

GKdNode *	buildTree (size_t count, size_t *pIndexes)
	Build the tree. More...

virtual size_t	findNearest (size_t k, size_t index)
	See the comment for GNeighborFinder::findNearest. More...

virtual size_t	findNearest (size_t k, const GVec &vector)
	See the comment for GNeighborFinderGeneralizing::neighbors. More...

size_t	findWithinRadius (double squaredRadius, size_t index)
	See the comment for GNeighborFinder::findWithinRadius. More...

size_t	findWithinRadius (double squaredRadius, const GVec &vector)
	See the comment for GNeighborFinderGeneralizing::findWithinRadius. More...

bool	isGreaterOrEqual (const double *pPat, size_t attr, double pivot)
	Returns true iff the specified point-vector is on the >= side of the specified pivot. More...

virtual void	reoptimize ()
	Rebuilds the tree to improve subsequent performance. This should be called after a significant number of point-vectors are added to or released from the internal set. More...

GKdNode *	root ()
	Returns the root node of the kd-tree. More...

void	setMaxLeafSize (size_t n)
	Specify the max number of point-vectors to store in each leaf node. More...

Public Member Functions inherited from GClasses::GNeighborFinderGeneralizing
	GNeighborFinderGeneralizing (const GMatrix pData, GDistanceMetric pMetric=NULL, bool ownMetric=false)
	Create a neighborfinder for finding the neighborCount nearest neighbors under the given metric. If ownMetric is true, then the neighborFinder takes responsibility for deleting the metric, otherwise it is the caller's responsibility. More...

virtual	~GNeighborFinderGeneralizing ()

virtual bool	canGeneralize ()
	Returns true. See the comment for GNeighborFinder::canGeneralize. More...

virtual double	distance (size_t i)
	See the comment for GNeighborFinder::distance. More...

GDistanceMetric *	metric ()
	Returns the metric. More...

virtual size_t	neighbor (size_t i)
	See the comment for GNeighborFinder::neighbor. More...

void	sortNeighbors (size_t start=0, size_t end=INVALID_INDEX)
	Uses Quick Sort to sort the neighbors from least to most distant. More...

Public Member Functions inherited from GClasses::GNeighborFinder
	GNeighborFinder (const GMatrix *pData)

virtual	~GNeighborFinder ()

const GMatrix *	data ()
	Returns the data passed to the constructor of this object. More...

virtual bool	isCached ()
	Returns true iff the neighbors and distances are pre-computed. More...

Static Public Member Functions
static double	medianDistanceToNeighbor (GMatrix &data, size_t n)
	Computes the median distance to the n^th closest neighbor of each row in data. More...

static void	test ()
	Performs unit tests for this class. Throws an exception if there is a failure. More...

Protected Member Functions
void	computePivotAndGoodness (size_t count, size_t pIndexes, size_t attr, double pOutPivot, double *pOutGoodness)
	Computes a good pivot for the specified attribute, and the goodness of splitting on that attribute. For continuous attributes, the pivot is the (not scaled) mean and the goodness is the scaled variance. For nominal attributes, the pivot is the most common value and the goodness is scaled entropy. More...

size_t	findNearest (size_t k, const GVec &vec, size_t nExclude)
	This is a helper method that finds the nearest neighbors. More...

size_t	findWithinRadius (double squaredRadius, const GVec &vec, size_t nExclude)
	This is a helper method that finds neighbors within a radius. More...

size_t	splitIndexes (size_t count, size_t *pIndexes, size_t attr, double pivot)
	Moves all the indexes that refer to rows that have a value less than pivot in the specified attribute to the beginning of the list, and the rest to the end. Returns the number of rows with a value less than the pivot. For nominal values, not-equal values are moved to the beginning, and equal values are moved to the end. More...

Protected Member Functions inherited from GClasses::GNeighborFinderGeneralizing
void	insertionSortNeighbors (size_t start, size_t end)
	A helper method used by sortNeighbors when the remaining portion to sort is small. More...

Protected Attributes
size_t	m_maxLeafSize

GKdNode *	m_pRoot

size_t	m_size

Protected Attributes inherited from GClasses::GNeighborFinderGeneralizing
std::vector< double >	m_dists

std::vector< size_t >	m_neighs

bool	m_ownMetric

GDistanceMetric *	m_pMetric

Protected Attributes inherited from GClasses::GNeighborFinder
const GMatrix *	m_pData

Constructor & Destructor Documentation

GClasses::GKdTree::GKdTree	(	const GMatrix *	pData,
		GDistanceMetric *	pMetric = `NULL`,
		bool	ownMetric = `false`
	)

virtual GClasses::GKdTree::~GKdTree ( )

virtual

Member Function Documentation

GKdNode* GClasses::GKdTree::buildTree	(	size_t	count,
		size_t *	pIndexes
	)

Build the tree.

void GClasses::GKdTree::computePivotAndGoodness	(	size_t	count,
		size_t *	pIndexes,
		size_t	attr,
		double *	pOutPivot,
		double *	pOutGoodness
	)

protected

Computes a good pivot for the specified attribute, and the goodness of splitting on that attribute. For continuous attributes, the pivot is the (not scaled) mean and the goodness is the scaled variance. For nominal attributes, the pivot is the most common value and the goodness is scaled entropy.

virtual size_t GClasses::GKdTree::findNearest	(	size_t	k,
		size_t	index
	)

virtual

See the comment for GNeighborFinder::findNearest.

Implements GClasses::GNeighborFinder.

virtual size_t GClasses::GKdTree::findNearest	(	size_t	k,
		const GVec &	vector
	)

virtual

See the comment for GNeighborFinderGeneralizing::neighbors.

Implements GClasses::GNeighborFinderGeneralizing.

size_t GClasses::GKdTree::findNearest	(	size_t	k,
		const GVec &	vec,
		size_t	nExclude
	)

protected

This is a helper method that finds the nearest neighbors.

size_t GClasses::GKdTree::findWithinRadius	(	double	squaredRadius,
		size_t	index
	)

virtual

See the comment for GNeighborFinder::findWithinRadius.

Implements GClasses::GNeighborFinder.

size_t GClasses::GKdTree::findWithinRadius	(	double	squaredRadius,
		const GVec &	vector
	)

virtual

See the comment for GNeighborFinderGeneralizing::findWithinRadius.

Implements GClasses::GNeighborFinderGeneralizing.

size_t GClasses::GKdTree::findWithinRadius	(	double	squaredRadius,
		const GVec &	vec,
		size_t	nExclude
	)

protected

This is a helper method that finds neighbors within a radius.

bool GClasses::GKdTree::isGreaterOrEqual	(	const double *	pPat,
		size_t	attr,
		double	pivot
	)

Returns true iff the specified point-vector is on the >= side of the specified pivot.

static double GClasses::GKdTree::medianDistanceToNeighbor	(	GMatrix &	data,
		size_t	n
	)

static

Computes the median distance to the n^th closest neighbor of each row in data.

virtual void GClasses::GKdTree::reoptimize ( )

virtual

Rebuilds the tree to improve subsequent performance. This should be called after a significant number of point-vectors are added to or released from the internal set.

Implements GClasses::GNeighborFinderGeneralizing.

GKdNode* GClasses::GKdTree::root ( )

inline

Returns the root node of the kd-tree.

void GClasses::GKdTree::setMaxLeafSize ( size_t n )

inline

Specify the max number of point-vectors to store in each leaf node.

size_t GClasses::GKdTree::splitIndexes	(	size_t	count,
		size_t *	pIndexes,
		size_t	attr,
		double	pivot
	)

protected

Moves all the indexes that refer to rows that have a value less than pivot in the specified attribute to the beginning of the list, and the rest to the end. Returns the number of rows with a value less than the pivot. For nominal values, not-equal values are moved to the beginning, and equal values are moved to the end.

static void GClasses::GKdTree::test ( )

static

Performs unit tests for this class. Throws an exception if there is a failure.

Member Data Documentation

size_t GClasses::GKdTree::m_maxLeafSize

protected

GKdNode* GClasses::GKdTree::m_pRoot

protected

size_t GClasses::GKdTree::m_size

protected

Detailed Description

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation