Package org.locationtech.jts.index.strtree

Class BoundablePair

java.lang.Object

org.locationtech.jts.index.strtree.BoundablePair

All Implemented Interfaces:

Comparable

class BoundablePair
extends Object
implements Comparable

A pair of Boundables, whose leaf items support a distance metric between them. Used to compute the distance between the members, and to expand a member relative to the other in order to produce new branches of the Branch-and-Bound evaluation tree. Provides an ordering based on the distance between the members, which allows building a priority queue by minimum distance.

Field Summary

Fields

Modifier and Type	Field	Description
private Boundable	boundable1
private Boundable	boundable2
private double	distance
private ItemDistance	itemDistance

Constructor Summary

Constructors

Constructor	Description
BoundablePair(Boundable boundable1, Boundable boundable2, ItemDistance itemDistance)

Method Summary

Modifier and Type	Method	Description
private static double	area(Boundable b)
int	compareTo(Object o)	Compares two pairs based on their minimum distances
private double	distance()	Computes the distance between the Boundables in this pair.
private void	expand(Boundable bndComposite, Boundable bndOther, PriorityQueue priQ, double minDistance)
void	expandToQueue(PriorityQueue priQ, double minDistance)	For a pair which is not a leaf (i.e.
Boundable	getBoundable(int i)	Gets one of the member Boundables in the pair (indexed by [0, 1]).
double	getDistance()	Gets the minimum possible distance between the Boundables in this pair.
static boolean	isComposite(Object item)
boolean	isLeaves()	Tests if both elements of the pair are leaf nodes

Methods inherited from class java.lang.Object

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

Field Details

boundable1

private Boundable boundable1

boundable2

private Boundable boundable2

distance

private double distance

itemDistance

private ItemDistance itemDistance

Constructor Details

BoundablePair

public BoundablePair(Boundable boundable1,
 Boundable boundable2,
 ItemDistance itemDistance)

Method Details

getBoundable

public Boundable getBoundable(int i)

Gets one of the member Boundables in the pair (indexed by [0, 1]).

Parameters:

i - the index of the member to return (0 or 1)

Returns:

the chosen member

distance

private double distance()

Computes the distance between the Boundables in this pair. The boundables are either composites or leaves. If either is composite, the distance is computed as the minimum distance between the bounds. If both are leaves, the distance is computed by

invalid reference

#itemDistance(ItemBoundable, ItemBoundable)

.

Returns:

getDistance

public double getDistance()

Gets the minimum possible distance between the Boundables in this pair. If the members are both items, this will be the exact distance between them. Otherwise, this distance will be a lower bound on the distances between the items in the members.

Returns:

the exact or lower bound distance for this pair

compareTo

public int compareTo(Object o)

Compares two pairs based on their minimum distances

Specified by:

compareTo in interface Comparable

isLeaves

public boolean isLeaves()

Tests if both elements of the pair are leaf nodes

Returns:

true if both pair elements are leaf nodes

isComposite

public static boolean isComposite(Object item)

area

private static double area(Boundable b)

expandToQueue

public void expandToQueue(PriorityQueue priQ,
 double minDistance)

For a pair which is not a leaf (i.e. has at least one composite boundable) computes a list of new pairs from the expansion of the larger boundable.

expand

private void expand(Boundable bndComposite,
 Boundable bndOther,
 PriorityQueue priQ,
 double minDistance)