Package elki.index.tree.metrical.vptree

Class VPTree.VPTreePrioritySearcher<Q>

java.lang.Object

elki.index.tree.metrical.vptree.VPTree.VPTreePrioritySearcher<Q>

Type Parameters:

Q - query type

All Implemented Interfaces:

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

Direct Known Subclasses:

VPTree.VPTreePriorityDBIDSearcher, VPTree.VPTreePriorityObjectSearcher

Enclosing class:

VPTree<O>

public abstract class VPTree.VPTreePrioritySearcher<Q>
extends java.lang.Object
implements PrioritySearcher<Q>

Priority search for the VP-Tree.

Author:

Robert Gehde, Erich Schubert

Field Summary

Fields

Modifier and Type	Field	Description
private DoubleDBIDListIter	candidates	Current iterator.
private VPTree.Node	cur	Current search position.
private double	curdist	Distance to the current object.
private DoubleObjectMinHeap<VPTree.Node>	heap	Min heap for searching.
private double	threshold	Stopping threshold.
private double	vpdist	Distance to the current object.

Constructor Summary

Constructors

Constructor	Description
VPTreePrioritySearcher()

Method Summary

Modifier and Type	Method	Description
PrioritySearcher<Q>	advance()	Moves the iterator forward to the next entry.
protected boolean	advanceQueue()	Expand the next node of the priority heap.
double	allLowerBound()	Lower bound for all subsequent instances (that have been completely explored).
double	computeExactDistance()	Compute the exact distance to the current candidate.
PrioritySearcher<Q>	decreaseCutoff(double threshold)	Decrease the cutoff threshold.
void	doSearch()	Start the search.
double	getApproximateAccuracy()	Get approximate distance accuracy (if available).
double	getApproximateDistance()	Get approximate distance (if available).
double	getLowerBound()	Get the lower bound (if available).
double	getUpperBound()	Get the upper bound (if available).
int	internalGetIndex()	Internal only: Get the internal index.
protected abstract double	queryDistance(DBIDRef p)	Compute the distance to a candidate 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

getKNN, getRange, search, search

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

getRange

Field Detail

heap

private DoubleObjectMinHeap<VPTree.Node> heap

Min heap for searching.

threshold

private double threshold

Stopping threshold.

cur

private VPTree.Node cur

Current search position.

candidates

private DoubleDBIDListIter candidates

Current iterator.

curdist

private double curdist

Distance to the current object.

vpdist

private double vpdist

Distance to the current object.

Constructor Detail

VPTreePrioritySearcher

public VPTreePrioritySearcher()

Method Detail

doSearch

public void doSearch()

Start the search.

advance

public PrioritySearcher<Q> 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<Q>

Returns:

The iterator itself.

advanceQueue

protected boolean advanceQueue()

Expand the next node of the priority heap.

queryDistance

protected abstract double queryDistance(DBIDRef p)

Compute the distance to a candidate object.

Parameters:

p - Object

Returns:

Distance

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<Q> 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<Q>

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<Q>

Returns:

Distance

getApproximateDistance

public double getApproximateDistance()

Description copied from interface: PrioritySearcher

Get approximate distance (if available).

Quality guarantees may vary a lot!

Specified by:

getApproximateDistance in interface PrioritySearcher<Q>

Returns:

Double.NaN if not valid

getApproximateAccuracy

public double getApproximateAccuracy()

Description copied from interface: PrioritySearcher

Get approximate distance accuracy (if available).

Quality guarantees may vary a lot!

Specified by:

getApproximateAccuracy in interface PrioritySearcher<Q>

Returns:

Double.NaN if not valid

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<Q>

Returns:

Double.NaN if not valid

getUpperBound

public double getUpperBound()

Description copied from interface: PrioritySearcher

Get the upper bound (if available).

Specified by:

getUpperBound in interface PrioritySearcher<Q>

Returns:

Double.NaN if not valid

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<Q>

Returns:

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