Package elki.index.tree.metrical.covertree

Class CoverTree.CoverTreePrioritySearcher<Q>

java.lang.Object

elki.index.tree.metrical.covertree.CoverTree.CoverTreePrioritySearcher<Q>

Type Parameters:

Q - query type

All Implemented Interfaces:

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

Direct Known Subclasses:

CoverTree.CoverTreePriorityDBIDSearcher, CoverTree.CoverTreePriorityObjectSearcher

Enclosing class:

CoverTree<O>

public abstract class CoverTree.CoverTreePrioritySearcher<Q>
extends java.lang.Object
implements PrioritySearcher<Q>

Priority query class.

Author:

Erich Schubert

Field Summary

Fields

Modifier and Type	Field	Description
private DoubleDBIDListIter	candidates	Candidates
private double	lb	Current lower bound.
private DoubleObjectMinHeap<CoverTree.Node>	pq	Priority queue
private double	routingDist	Distance to routing object.
(package private) double	threshold	Stopping distance threshold.
private DBIDVar	tmp	Temporary storage.

Constructor Summary

Constructors

Constructor	Description
CoverTreePrioritySearcher()	Constructor.

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.
protected PrioritySearcher<Q>	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 it)	Compute distance to 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

getKNN, getRange, search, search

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

getRange

Field Detail

threshold

double threshold

Stopping distance threshold.

tmp

private DBIDVar tmp

Temporary storage.

pq

private DoubleObjectMinHeap<CoverTree.Node> pq

Priority queue

candidates

private DoubleDBIDListIter candidates

Candidates

routingDist

private double routingDist

Distance to routing object.

lb

private double lb

Current lower bound.

Constructor Detail

CoverTreePrioritySearcher

public CoverTreePrioritySearcher()

Constructor.

Method Detail

queryDistance

protected abstract double queryDistance(DBIDRef it)

Compute distance to query object.

Parameters:

it - Candidate

Returns:

Distance

doSearch

protected PrioritySearcher<Q> doSearch()

Start the search.

Returns:

this.

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

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)

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.

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.

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

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

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