org.apache.lucene.facet.search.sampling
Class SamplingAccumulator

java.lang.Object
  org.apache.lucene.facet.search.FacetsAccumulator
      org.apache.lucene.facet.search.StandardFacetsAccumulator
          org.apache.lucene.facet.search.sampling.SamplingAccumulator

public class SamplingAccumulator
extends StandardFacetsAccumulator

Facets accumulation with sampling.

Note two major differences between this class and SamplingWrapper:

1. Latter can wrap any other FacetsAccumulator while this class directly extends StandardFacetsAccumulator.
2. This class can effectively apply sampling on the complement set of matching document, thereby working efficiently with the complement optimization - see FacetsAccumulator.getComplementThreshold().

Note: Sampling accumulation (Accumulation over a sampled-set of the results), does not guarantee accurate values for FacetResult.getNumValidDescendants() & FacetResultNode.getResidue().

See Also:

Sampler

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

Field Summary

Fields inherited from class org.apache.lucene.facet.search.StandardFacetsAccumulator

floatArrayAllocator, intArrayAllocator, isUsingComplements, maxPartitions, partitionSize

Fields inherited from class org.apache.lucene.facet.search.FacetsAccumulator

DEFAULT_COMPLEMENT_THRESHOLD, DISABLE_COMPLEMENT, FORCE_COMPLEMENT, indexReader, searchParams, taxonomyReader

Constructor Summary

SamplingAccumulator(Sampler sampler, FacetSearchParams searchParams, IndexReader indexReader, TaxonomyReader taxonomyReader)
Constructor...

SamplingAccumulator(Sampler sampler, FacetSearchParams searchParams, IndexReader indexReader, TaxonomyReader taxonomyReader, IntArrayAllocator intArrayAllocator, FloatArrayAllocator floatArrayAllocator)
Constructor...

Method Summary

List<FacetResult>	accumulate(ScoredDocIDs docids) Accumulate facets over given documents, according to facet requests in effect.
protected ScoredDocIDs	actualDocsToAccumulate(ScoredDocIDs docids) Set the actual set of documents over which accumulation should take place.
protected double	getTotalCountsFactor() Expert: factor by which counts should be multiplied when initializing the count arrays from total counts.

Methods inherited from class org.apache.lucene.facet.search.StandardFacetsAccumulator

getCategoryListMap, shouldComplement

Methods inherited from class org.apache.lucene.facet.search.FacetsAccumulator

getComplementThreshold, isAllowLabeling, mayComplement, setAllowLabeling, setComplementThreshold

Methods inherited from class java.lang.Object

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

Constructor Detail

SamplingAccumulator

public SamplingAccumulator(Sampler sampler,
                           FacetSearchParams searchParams,
                           IndexReader indexReader,
                           TaxonomyReader taxonomyReader,
                           IntArrayAllocator intArrayAllocator,
                           FloatArrayAllocator floatArrayAllocator)

Constructor...

SamplingAccumulator

public SamplingAccumulator(Sampler sampler,
                           FacetSearchParams searchParams,
                           IndexReader indexReader,
                           TaxonomyReader taxonomyReader)

Constructor...

Method Detail

accumulate

public List<FacetResult> accumulate(ScoredDocIDs docids)
                             throws IOException

Description copied from class: FacetsAccumulator

Accumulate facets over given documents, according to facet requests in effect.

Overrides:

accumulate in class StandardFacetsAccumulator

Parameters:

docids - documents (and their scores) for which facets are Accumulated.

Returns:

Accumulated facets.

Throws:

IOException - on error.

actualDocsToAccumulate

protected ScoredDocIDs actualDocsToAccumulate(ScoredDocIDs docids)
                                       throws IOException

Description copied from class: StandardFacetsAccumulator

Set the actual set of documents over which accumulation should take place.

Allows to override the set of documents to accumulate for. Invoked just before actual accumulating starts. From this point that set of documents remains unmodified. Default implementation just returns the input unchanged.

Overrides:

actualDocsToAccumulate in class StandardFacetsAccumulator

Parameters:

docids - candidate documents to accumulate for

Returns:

actual documents to accumulate for

Throws:

IOException

getTotalCountsFactor

protected double getTotalCountsFactor()

Description copied from class: StandardFacetsAccumulator

Expert: factor by which counts should be multiplied when initializing the count arrays from total counts. Default implementation for this returns 1, which is a no op.

Overrides:

getTotalCountsFactor in class StandardFacetsAccumulator

Returns:

a factor by which total counts should be multiplied