Package org.apache.lucene.spatial.prefix.tree

Class GeohashPrefixTree

java.lang.Object
org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree
org.apache.lucene.spatial.prefix.tree.GeohashPrefixTree
public class GeohashPrefixTree extends SpatialPrefixTree
A SpatialPrefixTree based on Geohashes. Uses GeohashUtils to do all the geohash work.
WARNING: This API is experimental and might change in incompatible ways in the next release.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    GeohashPrefixTree.Factory
    Factory for creating GeohashPrefixTree instances with useful defaults

  • Field Summary

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

    ctx, maxLevels

  • Constructor Summary

    Constructors
    Constructor
    Description
    GeohashPrefixTree(org.locationtech.spatial4j.context.SpatialContext ctx, int maxLevels)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    protected Cell
    getCell(org.locationtech.spatial4j.shape.Point p, int level)
    Returns the cell containing point p at the specified level.
    double
    getDistanceForLevel(int level)
    Given a cell having the specified level, returns the distance from opposite corners.
    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).
    static int
    getMaxLevelsPossible()
    Any more than this and there's no point (double lat and lon are the same).
    CellIterator
    getTreeCellIterator(org.locationtech.spatial4j.shape.Shape shape, int detailLevel)
    Gets the intersecting cells for the specified shape, without exceeding detail level.
    Cell
    getWorldCell()
    Returns the level 0 cell which encompasses all spatial data.
    Cell
    readCell(BytesRef term, Cell scratch)
    This creates a new Cell (or re-using scratch if provided), initialized to the state as read by the bytes.

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

    getMaxLevels, getSpatialContext, toString

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • GeohashPrefixTree

      public GeohashPrefixTree(org.locationtech.spatial4j.context.SpatialContext ctx, int maxLevels)

  • Method Details

    • getMaxLevelsPossible

      public static int getMaxLevelsPossible()
      Any more than this and there's no point (double lat and lon are the same).

    • getWorldCell

      public Cell getWorldCell()
      Description copied from class: SpatialPrefixTree
      Returns the level 0 cell which encompasses all spatial data. Equivalent to SpatialPrefixTree.readCell(BytesRef,Cell) with no bytes.
      Specified by:
      getWorldCell in class SpatialPrefixTree

    • 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

      protected Cell getCell(org.locationtech.spatial4j.shape.Point p, int level)
      Returns the cell containing point p at the specified level.

    • getDistanceForLevel

      public double getDistanceForLevel(int level)
      Description copied from class: SpatialPrefixTree
      Given a cell having the specified level, returns the distance from opposite corners. Since this might vary depending on where the cell is, this method may over-estimate.
      Specified by:
      getDistanceForLevel in class SpatialPrefixTree
      Parameters:
      level - [1 to maxLevels]
      Returns:
      > 0

    • readCell

      public Cell readCell(BytesRef term, Cell scratch)
      Description copied from class: SpatialPrefixTree
      This creates a new Cell (or re-using scratch if provided), initialized to the state as read by the bytes. Warning: An implementation may refer to the same byte array (no copy). If Cell.setLeaf() is subsequently called, it would then modify these bytes.
      Specified by:
      readCell in class SpatialPrefixTree

    • getTreeCellIterator

      public CellIterator getTreeCellIterator(org.locationtech.spatial4j.shape.Shape shape, int detailLevel)
      Description copied from class: SpatialPrefixTree
      Gets the intersecting cells for the specified shape, without exceeding detail level. If a cell is within the query shape then it's marked as a leaf and none of its children are added. For cells at detailLevel, they are marked as leaves too, unless it's a point.

      IMPORTANT: Cells returned from the iterator can be re-used for cells at the same level. So you can't simply iterate to subsequent cells and still refer to the former cell nor the bytes returned from the former cell, unless you know the former cell is a parent.

      Overrides:
      getTreeCellIterator in class SpatialPrefixTree
      Parameters:
      shape - the shape; possibly null but the caller should liberally call remove() if so.
      detailLevel - the maximum detail level to get cells for
      Returns:
      the matching cells