Package elki.index.tree.metrical.vptree

Class GNAT.GNATPrioritySearcher<T>

java.lang.Object

elki.index.tree.metrical.vptree.GNAT.GNATPrioritySearcher<T>

Type Parameters:

T - Query object

All Implemented Interfaces:

DBIDIter, DBIDRef, KNNSearcher<T>, PrioritySearcher<T>, RangeSearcher<T>, Iter

Direct Known Subclasses:

GNAT.GNATPriorityDBIDSearcher, GNAT.GNATPriorityObjectSearcher

Enclosing class:

GNAT<O>

public abstract class GNAT.GNATPrioritySearcher<T>
extends java.lang.Object
implements PrioritySearcher<T>

priority search query for mvp-tree

Author:

Robert Gehde

Field Summary

Fields

Modifier and Type	Field	Description
private GNAT.PrioritySearchBranch	cur	Current search position.
private ComparableMinHeap<GNAT.PrioritySearchBranch>	heap	Min heap for searching.
private double	threshold	Stopping threshold.

Constructor Summary

Constructors

Constructor	Description
GNATPrioritySearcher()

Method Summary

Modifier and Type	Method	Description
PrioritySearcher<T>	advance()	Moves the iterator forward to the next entry.
double	allLowerBound()	Lower bound for all subsequent instances (that have been completely explored).
double	computeExactDistance()	Compute the exact distance to the current candidate.
PrioritySearcher<T>	decreaseCutoff(double threshold)	Decrease the cutoff threshold.
protected PrioritySearcher<T>	doSearch()	Start the next search.
double	getLowerBound()	Get the lower bound (if available).
int	internalGetIndex()	Internal only: Get the internal index.
protected abstract double	queryDistance(DBIDRef iter)	Query the distance to a query object.
boolean	valid()	Returns true if the iterator currently points to a valid object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface elki.database.ids.DBIDIter

addTo

Methods inherited from interface elki.database.ids.DBIDRef

equals, hashCode

Methods inherited from interface elki.database.query.PrioritySearcher

getApproximateAccuracy, getApproximateDistance, getKNN, getRange, getUpperBound, search, search

Methods inherited from interface elki.database.query.range.RangeSearcher

getRange

Field Detail

heap

private ComparableMinHeap<GNAT.PrioritySearchBranch> heap

Min heap for searching.

threshold

private double threshold

Stopping threshold.

cur

private GNAT.PrioritySearchBranch cur

Current search position.

Constructor Detail

GNATPrioritySearcher

public GNATPrioritySearcher()

Method Detail

doSearch

protected PrioritySearcher<T> doSearch()

Start the next search.

Returns:

Searcher

advance

public PrioritySearcher<T> advance()

Description copied from interface: Iter

Moves the iterator forward to the next entry.

Specified by:

advance in interface DBIDIter

Specified by:

advance in interface Iter

Specified by:

advance in interface PrioritySearcher<T>

Returns:

The iterator itself.

internalGetIndex

public int internalGetIndex()

Description copied from interface: DBIDRef

Internal only: Get the internal index.

NOT FOR PUBLIC USE - ELKI Optimization engine only.

Specified by:

internalGetIndex in interface DBIDRef

Returns:

Internal index

valid

public boolean valid()

Description copied from interface: Iter

Returns true if the iterator currently points to a valid object.

Specified by:

valid in interface Iter

Returns:

a boolean value, whether the position is valid.

decreaseCutoff

public PrioritySearcher<T> decreaseCutoff(double threshold)

Description copied from interface: PrioritySearcher

Decrease the cutoff threshold.

The cutoff must not be increased, as the search may have pruned some results automatically.

Specified by:

decreaseCutoff in interface PrioritySearcher<T>

Parameters:

threshold - Threshold parameter

Returns:

this, for chaining

computeExactDistance

public double computeExactDistance()

Description copied from interface: PrioritySearcher

Compute the exact distance to the current candidate.

The searcher may or may not have this value already.

Specified by:

computeExactDistance in interface PrioritySearcher<T>

Returns:

Distance

allLowerBound

public double allLowerBound()

Description copied from interface: PrioritySearcher

Lower bound for all subsequent instances (that have been completely explored). The searcher guarantees that no further results will be returned with a distance less than this.

Specified by:

allLowerBound in interface PrioritySearcher<T>

Returns:

lower bound; 0 if no guarantees (e.g., linear scan)

getLowerBound

public double getLowerBound()

Description copied from interface: PrioritySearcher

Get the lower bound (if available).

Note: the lower bound is already checked by the cutoff of the priority search, so this is primarily useful for analyzing the search behavior.

Specified by:

getLowerBound in interface PrioritySearcher<T>

Returns:

Double.NaN if not valid

queryDistance

protected abstract double queryDistance(DBIDRef iter)

Query the distance to a query object.

Parameters:

iter - Target object

Returns:

Distance