Class S2PrefixTree
java.lang.Object
org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree
org.apache.lucene.spatial.prefix.tree.S2PrefixTree
Spatial prefix tree for S2 Geometry. Shape factories for the
given
SpatialContext
must implement the interface S2ShapeFactory
.
The tree can be configured on how it divided itself by providing an arity. The default arity is 1 which divided every sub-cell in 4 (except the first level that is always divided by 6) . Arity 2 divides sub-cells in 16 and arity 3 in 64 sub-cells.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Nested Class Summary
Modifier and TypeClassDescriptionprotected static class
Factory for creatingS2PrefixTree
instances with useful defaults -
Field Summary
Fields inherited from class org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree
ctx, maxLevels
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Constructor Summary
ConstructorDescriptionS2PrefixTree
(org.locationtech.spatial4j.context.SpatialContext ctx, int maxLevels) Creates a S2 spatial tree with arity 1.S2PrefixTree
(org.locationtech.spatial4j.context.SpatialContext ctx, int maxLevels, int arity) Creates a S2 spatial tree with provided arity. -
Method Summary
Modifier and TypeMethodDescriptiondouble
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
getMaxLevels
(int arity) Get max levels for this spatial tree.getTreeCellIterator
(org.locationtech.spatial4j.shape.Shape shape, int detailLevel) Gets the intersecting cells for the specified shape, without exceeding detail level.Returns the level 0 cell which encompasses all spatial data.This creates a new Cell (or re-usingscratch
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
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Field Details
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s2ShapeFactory
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arity
protected final int arity
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Constructor Details
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S2PrefixTree
public S2PrefixTree(org.locationtech.spatial4j.context.SpatialContext ctx, int maxLevels) Creates a S2 spatial tree with arity 1.- Parameters:
ctx
- The provided spatial context. The shape factor of the spatial context must implementS2ShapeFactory
maxLevels
- The provided maximum level for this tree.
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S2PrefixTree
public S2PrefixTree(org.locationtech.spatial4j.context.SpatialContext ctx, int maxLevels, int arity) Creates a S2 spatial tree with provided arity.- Parameters:
ctx
- The provided spatial context. The shape factor of the spatial context must implementS2ShapeFactory
maxLevels
- The provided maximum level for this tree.arity
- The arity of the tree.
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Method Details
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getMaxLevels
public static int getMaxLevels(int arity) Get max levels for this spatial tree.- Parameters:
arity
- The arity of the tree.- Returns:
- The maximum number of levels by the provided arity.
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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). Consequentlydist
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 classSpatialPrefixTree
- Parameters:
dist
->= 0
- Returns:
- level [1 to maxLevels]
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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 classSpatialPrefixTree
- Parameters:
level
- [1 to maxLevels]- Returns:
> 0
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getWorldCell
Description copied from class:SpatialPrefixTree
Returns the level 0 cell which encompasses all spatial data. Equivalent toSpatialPrefixTree.readCell(BytesRef,Cell)
with no bytes.- Specified by:
getWorldCell
in classSpatialPrefixTree
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readCell
Description copied from class:SpatialPrefixTree
This creates a new Cell (or re-usingscratch
if provided), initialized to the state as read by the bytes. Warning: An implementation may refer to the same byte array (no copy). IfCell.setLeaf()
is subsequently called, it would then modify these bytes.- Specified by:
readCell
in classSpatialPrefixTree
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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 classSpatialPrefixTree
- Parameters:
shape
- the shape; possibly null but the caller should liberally callremove()
if so.detailLevel
- the maximum detail level to get cells for- Returns:
- the matching cells
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