org.apache.lucene.spatial.prefix

Class PrefixTreeFacetCounter

java.lang.Object

org.apache.lucene.spatial.prefix.PrefixTreeFacetCounter

public class PrefixTreeFacetCounter
extends Object

Computes facets on cells for PrefixTreeStrategy.

NOTE: If for a given document and a given field using RecursivePrefixTreeStrategy multiple values are indexed (i.e. multi-valued) and at least one of them is a non-point, then there is a possibility of double-counting the document in the facet results. Since each shape is independently turned into grid cells at a resolution chosen by the shape's size, it's possible they will be indexed at different resolutions. This means the document could be present in BOTH the postings for a cell in both its prefix and leaf variants. To avoid this, use a single valued field with a ShapeCollection (or WKT equivalent). Or calculate a suitable level/distErr to index both and call PrefixTreeStrategy.createIndexableFields(org.locationtech.spatial4j.shape.Shape, int) with the same value for all shapes for a given document/field.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	PrefixTreeFacetCounter.FacetVisitor A callback/visitor of facet counts.

Method Summary

Modifier and Type	Method and Description
static void	compute(PrefixTreeStrategy strategy, IndexReaderContext context, Bits topAcceptDocs, org.locationtech.spatial4j.shape.Shape queryShape, int facetLevel, PrefixTreeFacetCounter.FacetVisitor facetVisitor) Computes facets using a callback/visitor style design, allowing flexibility for the caller to determine what to do with each underlying count.
static void	compute(PrefixTreeStrategy strategy, LeafReaderContext context, Bits acceptDocs, org.locationtech.spatial4j.shape.Shape queryShape, int facetLevel, PrefixTreeFacetCounter.FacetVisitor facetVisitor) Lower-level per-leaf segment method.

Methods inherited from class java.lang.Object

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

Method Detail

compute

public static void compute(PrefixTreeStrategy strategy,
                           IndexReaderContext context,
                           Bits topAcceptDocs,
                           org.locationtech.spatial4j.shape.Shape queryShape,
                           int facetLevel,
                           PrefixTreeFacetCounter.FacetVisitor facetVisitor)
                    throws IOException

Computes facets using a callback/visitor style design, allowing flexibility for the caller to determine what to do with each underlying count.

Parameters:

strategy - the prefix tree strategy (contains the field reference, grid, max levels)

context - the IndexReader's context

topAcceptDocs - a Bits to limit counted docs. If null, live docs are counted.

queryShape - the shape to limit the range of facet counts to

facetLevel - the maximum depth (detail) of faceted cells

facetVisitor - the visitor/callback to receive the counts

Throws:

IOException

compute

public static void compute(PrefixTreeStrategy strategy,
                           LeafReaderContext context,
                           Bits acceptDocs,
                           org.locationtech.spatial4j.shape.Shape queryShape,
                           int facetLevel,
                           PrefixTreeFacetCounter.FacetVisitor facetVisitor)
                    throws IOException

Lower-level per-leaf segment method.

Throws:

IOException