org.apache.lucene.spatial.prefix.tree

Class QuadPrefixTree

java.lang.Object

org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree

org.apache.lucene.spatial.prefix.tree.QuadPrefixTree

public class QuadPrefixTree
extends SpatialPrefixTree

A SpatialPrefixTree which uses a quad tree in which an indexed term will be generated for each node, 'A', 'B', 'C', 'D'.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	QuadPrefixTree.Factory Factory for creating QuadPrefixTree instances with useful defaults

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_LEVELS
double	gridH
static int	MAX_LEVELS_POSSIBLE

Fields inherited from class org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree

ctx, maxLevels, UTF8

Constructor Summary

Constructors

Constructor and Description
QuadPrefixTree(com.spatial4j.core.context.SpatialContext ctx)
QuadPrefixTree(com.spatial4j.core.context.SpatialContext ctx, int maxLevels)
QuadPrefixTree(com.spatial4j.core.context.SpatialContext ctx, com.spatial4j.core.shape.Rectangle bounds, int maxLevels)

Method Summary

Methods

Modifier and Type	Method and Description
int	getLevelForDistance(double dist) Returns the level of the largest grid in which its longest side is less than or equal to the provided distance (in degrees).
Node	getNode(byte[] bytes, int offset, int len)
Node	getNode(com.spatial4j.core.shape.Point p, int level)
Node	getNode(String token) The cell for the specified token.
List<Node>	getNodes(com.spatial4j.core.shape.Shape shape, int detailLevel, boolean inclParents) Gets the intersecting & including cells for the specified shape, without exceeding detail level.
void	printInfo(PrintStream out)

Methods inherited from class org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree

getMaxLevels, getNode, getNodesAltPoint, getSpatialContext, getWorldNode, nodesToTokenStrings, toString

Methods inherited from class java.lang.Object

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

Field Detail

MAX_LEVELS_POSSIBLE

public static final int MAX_LEVELS_POSSIBLE

See Also:

Constant Field Values

DEFAULT_MAX_LEVELS

public static final int DEFAULT_MAX_LEVELS

See Also:

Constant Field Values

gridH

public final double gridH

Constructor Detail

QuadPrefixTree

public QuadPrefixTree(com.spatial4j.core.context.SpatialContext ctx,
              com.spatial4j.core.shape.Rectangle bounds,
              int maxLevels)

QuadPrefixTree

public QuadPrefixTree(com.spatial4j.core.context.SpatialContext ctx)

QuadPrefixTree

public QuadPrefixTree(com.spatial4j.core.context.SpatialContext ctx,
              int maxLevels)

Method Detail

printInfo

public void printInfo(PrintStream out)

getLevelForDistance

public int getLevelForDistance(double dist)

Description copied from class: SpatialPrefixTree

Returns the level of the largest grid in which its longest side is less than or equal to the provided distance (in degrees). Consequently dist acts as an error epsilon declaring the amount of detail needed in the grid, such that you can get a grid with just the right amount of precision.

Specified by:

getLevelForDistance in class SpatialPrefixTree

Parameters:

dist - >= 0

Returns:

level [1 to maxLevels]

getNode

public Node getNode(com.spatial4j.core.shape.Point p,
           int level)

Overrides:

getNode in class SpatialPrefixTree

getNode

public Node getNode(String token)

Description copied from class: SpatialPrefixTree

The cell for the specified token. The empty string should be equal to SpatialPrefixTree.getWorldNode(). Precondition: Never called when token length > maxLevel.

Specified by:

getNode in class SpatialPrefixTree

getNode

public Node getNode(byte[] bytes,
           int offset,
           int len)

Specified by:

getNode in class SpatialPrefixTree

getNodes

public List<Node> getNodes(com.spatial4j.core.shape.Shape shape,
                  int detailLevel,
                  boolean inclParents)

Description copied from class: SpatialPrefixTree

Gets the intersecting & including cells for the specified shape, without exceeding detail level. The result is a set of cells (no dups), sorted. Unmodifiable.

This implementation checks if shape is a Point and if so uses an implementation that recursively calls Node.getSubCell(com.spatial4j.core.shape.Point). Cell subclasses ideally implement that method with a quick implementation, otherwise, subclasses should override this method to invoke SpatialPrefixTree.getNodesAltPoint(com.spatial4j.core.shape.Point, int, boolean). TODO consider another approach returning an iterator -- won't build up all cells in memory.

Overrides:

getNodes in class SpatialPrefixTree