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

Class 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.

    • Constructor Detail

      • GeohashPrefixTree

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

    • Method Detail

      • getMaxLevelsPossible

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

      • 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