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

Class QuadPrefixTree

  • Direct Known Subclasses:
    PackedQuadPrefixTree
    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.

    • Field Detail

      • xmin

        protected final double xmin

      • xmax

        protected final double xmax

      • ymin

        protected final double ymin

      • ymax

        protected final double ymax

      • xmid

        protected final double xmid

      • ymid

        protected final double ymid

      • gridW

        protected final double gridW

      • gridH

        public final double gridH

      • robust

        protected boolean robust

    • Constructor Detail

      • QuadPrefixTree

        public QuadPrefixTree​(org.locationtech.spatial4j.context.SpatialContext ctx,
                      org.locationtech.spatial4j.shape.Rectangle bounds,
                      int maxLevels)

      • QuadPrefixTree

        public QuadPrefixTree​(org.locationtech.spatial4j.context.SpatialContext ctx)

      • QuadPrefixTree

        public QuadPrefixTree​(org.locationtech.spatial4j.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​(org.locationtech.spatial4j.shape.Point p,
                    int level)
        Returns the cell containing point p at the specified level.

      • checkBattenbergNotRobustly

        protected void checkBattenbergNotRobustly​(char c,
                                          double cx,
                                          double cy,
                                          int level,
                                          List<Cell> matches,
                                          BytesRef str,
                                          org.locationtech.spatial4j.shape.Shape shape,
                                          int maxLevel)

      • battenberg

        protected int battenberg​(double xmid,
                         double ymid,
                         double xp,
                         double yp)
        Returns a Z-Order quadrant [0-3].

      • 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