Class KdTree
- java.lang.Object
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- org.locationtech.jts.index.kdtree.KdTree
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public class KdTree extends java.lang.Object
An implementation of a 2-D KD-Tree. KD-trees provide fast range searching on point data.This implementation supports detecting and snapping points which are closer than a given distance tolerance. If the same point (up to tolerance) is inserted more than once, it is snapped to the existing node. In other words, if a point is inserted which lies within the tolerance of a node already in the index, it is snapped to that node. When a point is snapped to a node then a new node is not created but the count of the existing node is incremented. If more than one node in the tree is within tolerance of an inserted point, the closest and then lowest node is snapped to.
- Author:
- David Skea, Martin Davis
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description KdNode
insert(Coordinate p)
Inserts a new point in the kd-tree, with no data.KdNode
insert(Coordinate p, java.lang.Object data)
Inserts a new point into the kd-tree.boolean
isEmpty()
Tests whether the index contains any items.java.util.List
query(Envelope queryEnv)
Performs a range search of the points in the index.void
query(Envelope queryEnv, java.util.List result)
Performs a range search of the points in the index.void
query(Envelope queryEnv, KdNodeVisitor visitor)
Performs a range search of the points in the index and visits all nodes found.static Coordinate[]
toCoordinates(java.util.Collection kdnodes)
Converts a collection ofKdNode
s to an array ofCoordinate
s.static Coordinate[]
toCoordinates(java.util.Collection kdnodes, boolean includeRepeated)
Converts a collection ofKdNode
s to an array ofCoordinate
s, specifying whether repeated nodes should be represented by multiple coordinates.
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Constructor Detail
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KdTree
public KdTree()
Creates a new instance of a KdTree with a snapping tolerance of 0.0. (I.e. distinct points will not be snapped)
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KdTree
public KdTree(double tolerance)
Creates a new instance of a KdTree, specifying a snapping distance tolerance. Points which lie closer than the tolerance to a point already in the tree will be treated as identical to the existing point.- Parameters:
tolerance
- the tolerance distance for considering two points equal
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Method Detail
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toCoordinates
public static Coordinate[] toCoordinates(java.util.Collection kdnodes)
Converts a collection ofKdNode
s to an array ofCoordinate
s.- Parameters:
kdnodes
- a collection of nodes- Returns:
- an array of the coordinates represented by the nodes
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toCoordinates
public static Coordinate[] toCoordinates(java.util.Collection kdnodes, boolean includeRepeated)
Converts a collection ofKdNode
s to an array ofCoordinate
s, specifying whether repeated nodes should be represented by multiple coordinates.- Parameters:
kdnodes
- a collection of nodesincludeRepeated
- true if repeated nodes should be included multiple times- Returns:
- an array of the coordinates represented by the nodes
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isEmpty
public boolean isEmpty()
Tests whether the index contains any items.- Returns:
- true if the index does not contain any items
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insert
public KdNode insert(Coordinate p)
Inserts a new point in the kd-tree, with no data.- Parameters:
p
- the point to insert- Returns:
- the kdnode containing the point
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insert
public KdNode insert(Coordinate p, java.lang.Object data)
Inserts a new point into the kd-tree.- Parameters:
p
- the point to insertdata
- a data item for the point- Returns:
- returns a new KdNode if a new point is inserted, else an existing node is returned with its counter incremented. This can be checked by testing returnedNode.getCount() > 1.
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query
public void query(Envelope queryEnv, KdNodeVisitor visitor)
Performs a range search of the points in the index and visits all nodes found.- Parameters:
queryEnv
- the range rectangle to queryvisitor
- a visitor to visit all nodes found by the search
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query
public java.util.List query(Envelope queryEnv)
Performs a range search of the points in the index.- Parameters:
queryEnv
- the range rectangle to query- Returns:
- a list of the KdNodes found
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query
public void query(Envelope queryEnv, java.util.List result)
Performs a range search of the points in the index.- Parameters:
queryEnv
- the range rectangle to queryresult
- a list to accumulate the result nodes into
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