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 cell, 'A', 'B', 'C', 'D'.

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

Nested Class Summary

static class

QuadPrefixTree.Factory Factory for creating QuadPrefixTree instances with useful defaults

Field Summary

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

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

Cell	getCell(byte[] bytes, int offset, int len)
Cell	getCell(com.spatial4j.core.shape.Point p, int level) Returns the cell containing point p at the specified level.
Cell	getCell(String token) The cell for the specified token.
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).
void	printInfo(PrintStream out)

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

cellsToTokenStrings, getCell, getCells, getCells, getDistanceForLevel, getMaxLevels, getSpatialContext, getWorldCell, 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]

getCell

public Cell getCell(com.spatial4j.core.shape.Point p,
                    int level)

Description copied from class: SpatialPrefixTree

Returns the cell containing point p at the specified level.

Overrides:

getCell in class SpatialPrefixTree

getCell

public Cell getCell(String token)

Description copied from class: SpatialPrefixTree

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

Specified by:

getCell in class SpatialPrefixTree

getCell

public Cell getCell(byte[] bytes,
                    int offset,
                    int len)

Specified by:

getCell in class SpatialPrefixTree