package org.apache.lucene.facet.sampling;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.lucene.facet.params.FacetSearchParams;
import org.apache.lucene.facet.partitions.PartitionsFacetResultsHandler;
import org.apache.lucene.facet.sampling.Sampler.SampleResult;
import org.apache.lucene.facet.search.FacetArrays;
import org.apache.lucene.facet.search.FacetResult;
import org.apache.lucene.facet.search.FacetsAccumulator;
import org.apache.lucene.facet.search.ScoredDocIDs;
import org.apache.lucene.facet.search.StandardFacetsAccumulator;
import org.apache.lucene.facet.taxonomy.TaxonomyReader;
import org.apache.lucene.index.IndexReader;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Facets accumulation with sampling.<br>
* <p>
* Note two major differences between this class and {@link SamplingWrapper}:
* <ol>
* <li>Latter can wrap any other {@link FacetsAccumulator} while this class
* directly extends {@link StandardFacetsAccumulator}.</li>
* <li>This class can effectively apply sampling on the complement set of
* matching document, thereby working efficiently with the complement
* optimization - see {@link StandardFacetsAccumulator#getComplementThreshold()}
* .</li>
* </ol>
* <p>
* Note: Sampling accumulation (Accumulation over a sampled-set of the results),
* does not guarantee accurate values for
* {@link FacetResult#getNumValidDescendants()}.
*
* @see Sampler
* @lucene.experimental
*/
public class SamplingAccumulator extends StandardFacetsAccumulator {
private double samplingRatio = -1d;
private final Sampler sampler;
public SamplingAccumulator(Sampler sampler, FacetSearchParams searchParams,
IndexReader indexReader, TaxonomyReader taxonomyReader,
FacetArrays facetArrays) {
super(searchParams, indexReader, taxonomyReader, facetArrays);
this.sampler = sampler;
}
/**
* Constructor...
*/
public SamplingAccumulator(
Sampler sampler,
FacetSearchParams searchParams,
IndexReader indexReader, TaxonomyReader taxonomyReader) {
super(searchParams, indexReader, taxonomyReader);
this.sampler = sampler;
}
@Override
public List<FacetResult> accumulate(ScoredDocIDs docids) throws IOException {
// Replacing the original searchParams with the over-sampled
FacetSearchParams original = searchParams;
SampleFixer samplerFixer = sampler.samplingParams.getSampleFixer();
final boolean shouldOversample = sampler.samplingParams.shouldOverSample();
if (shouldOversample) {
searchParams = sampler.overSampledSearchParams(original);
}
List<FacetResult> sampleRes = super.accumulate(docids);
List<FacetResult> results = new ArrayList<FacetResult>();
for (FacetResult fres : sampleRes) {
// for sure fres is not null because this is guaranteed by the delegee.
PartitionsFacetResultsHandler frh = createFacetResultsHandler(fres.getFacetRequest());
if (samplerFixer != null) {
// fix the result of current request
samplerFixer.fixResult(docids, fres, samplingRatio);
fres = frh.rearrangeFacetResult(fres); // let delegee's handler do any arranging it needs to
if (shouldOversample) {
// Using the sampler to trim the extra (over-sampled) results
fres = sampler.trimResult(fres);
}
}
// final labeling if allowed (because labeling is a costly operation)
if (fres.getFacetResultNode().ordinal == TaxonomyReader.INVALID_ORDINAL) {
// category does not exist, add an empty result
results.add(emptyResult(fres.getFacetResultNode().ordinal, fres.getFacetRequest()));
} else {
frh.labelResult(fres);
results.add(fres);
}
}
searchParams = original; // Back to original params
return results;
}
@Override
protected ScoredDocIDs actualDocsToAccumulate(ScoredDocIDs docids) throws IOException {
SampleResult sampleRes = sampler.getSampleSet(docids);
samplingRatio = sampleRes.actualSampleRatio;
return sampleRes.docids;
}
@Override
protected double getTotalCountsFactor() {
if (samplingRatio<0) {
throw new IllegalStateException("Total counts ratio unavailable because actualDocsToAccumulate() was not invoked");
}
return samplingRatio;
}
}