Package org.apache.sedona.core.spatialPartitioning

Class QuadTreeRTPartitioning

java.lang.Object

org.apache.sedona.core.spatialPartitioning.QuadtreePartitioning

org.apache.sedona.core.spatialPartitioning.QuadTreeRTPartitioning

All Implemented Interfaces:

Serializable

public class QuadTreeRTPartitioning
extends QuadtreePartitioning

The class is used to build an R-tree over a random sample of another dataset and uses distance bounds to ensure efficient local kNN joins.

By calculating distance bounds and using circle range queries, it ensures that the subsets Si, containing all necessary points for accurate kNN results. The final union of local join results provides the complete kNN join result for the datasets R and S.

It generates List<List> expandedPartitionedBoundaries based on the quad tree.

See Also:

• Serialized Form

Field Summary

Fields inherited from class org.apache.sedona.core.spatialPartitioning.QuadtreePartitioning

partitionTree

Constructor Summary

Constructors

Constructor	Description
QuadTreeRTPartitioning(List<org.locationtech.jts.geom.Envelope> samples, org.locationtech.jts.geom.Envelope boundary, int partitions)
QuadTreeRTPartitioning(List<org.locationtech.jts.geom.Envelope> samples, org.locationtech.jts.geom.Envelope boundary, int partitions, int minTreeLevel)

Method Summary

Modifier and Type	Method	Description
org.locationtech.jts.index.strtree.STRtree	buildSTRTree(List<org.locationtech.jts.geom.Envelope> samples, int k)	This function is used to build the STR tree from the quad-tree built from the samples.
HashMap<Integer,List<org.locationtech.jts.geom.Envelope>>	getMbrs()
org.locationtech.jts.index.strtree.STRtree	getMbrSpatialIndex()
double	getMinimalEnvelopeWidth(List<QuadRectangle> partitionMBRs)	This function is used to calculate the minimal envelope width of the partitioned MBRs.
void	processPartitions(List<QuadRectangle> partitionMBRs, Map<Integer,List<org.locationtech.jts.geom.Envelope>> mbrs, int k, org.locationtech.jts.index.strtree.STRtree sampleTree, org.locationtech.jts.geom.GeometryFactory geometryFactory)

Methods inherited from class org.apache.sedona.core.spatialPartitioning.QuadtreePartitioning

getPartitionTree

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

QuadTreeRTPartitioning

public QuadTreeRTPartitioning(List<org.locationtech.jts.geom.Envelope> samples,
 org.locationtech.jts.geom.Envelope boundary,
 int partitions)
                       throws Exception

Throws:

Exception

QuadTreeRTPartitioning

public QuadTreeRTPartitioning(List<org.locationtech.jts.geom.Envelope> samples,
 org.locationtech.jts.geom.Envelope boundary,
 int partitions,
 int minTreeLevel)
                       throws Exception

Throws:

Exception

Method Details

getMbrs

public HashMap<Integer,List<org.locationtech.jts.geom.Envelope>> getMbrs()

getMbrSpatialIndex

public org.locationtech.jts.index.strtree.STRtree getMbrSpatialIndex()

buildSTRTree

public org.locationtech.jts.index.strtree.STRtree buildSTRTree(List<org.locationtech.jts.geom.Envelope> samples,
 int k)

This function is used to build the STR tree from the quad-tree built from the samples. It is used to expand the partitioned boundaries.

Parameters:

samples - the samples

k - the number of neighbor samples

Returns:

processPartitions

public void processPartitions(List<QuadRectangle> partitionMBRs,
 Map<Integer,List<org.locationtech.jts.geom.Envelope>> mbrs,
 int k,
 org.locationtech.jts.index.strtree.STRtree sampleTree,
 org.locationtech.jts.geom.GeometryFactory geometryFactory)

getMinimalEnvelopeWidth

public double getMinimalEnvelopeWidth(List<QuadRectangle> partitionMBRs)

This function is used to calculate the minimal envelope width of the partitioned MBRs.

Parameters:

partitionMBRs -

Returns: