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

Class PackedQuadPrefixTree

  • public class PackedQuadPrefixTree
extends QuadPrefixTree
    Uses a compact binary representation of 8 bytes to encode a spatial quad trie. The binary representation is as follows: 
     CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCDDDDDL

 Where C = Cell bits (2 per quad)
       D = Depth bits (5 with max of 29 levels)
       L = isLeaf bit
    It includes a built-in "pruneLeafyBranches" setting (true by default) similar to RecursivePrefixTreeStrategy.setPruneLeafyBranches(boolean) although this one only prunes at the target detail level (where it has the most effect). Usually you should disable RPT's prune, since it is very memory in-efficient.
    WARNING: This API is experimental and might change in incompatible ways in the next release.

    • Field Detail

      • QUAD

        protected static final byte[] QUAD

      • leafyPrune

        protected boolean leafyPrune

    • Constructor Detail

      • PackedQuadPrefixTree

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

    • Method Detail

      • getCell

        public Cell getCell​(org.locationtech.spatial4j.shape.Point p,
                    int level)
        Returns the cell containing point p at the specified level.
        Overrides:
        getCell in class QuadPrefixTree

      • build

        protected void build​(double x,
                     double y,
                     int level,
                     List<Cell> matches,
                     long term,
                     org.locationtech.spatial4j.shape.Shape shape,
                     int maxLevel)

      • checkBattenberg

        protected void checkBattenberg​(byte quad,
                               double cx,
                               double cy,
                               int level,
                               List<Cell> matches,
                               long term,
                               org.locationtech.spatial4j.shape.Shape shape,
                               int maxLevel)

      • 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.

      • 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.

        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

      • isPruneLeafyBranches

        public boolean isPruneLeafyBranches()

      • 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