org.apache.mahout.utils.vectors.lucene.AbstractLuceneIterator.java Source code

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Here is the source code for org.apache.mahout.utils.vectors.lucene.AbstractLuceneIterator.java

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/**
 * 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.
 */

package org.apache.mahout.utils.vectors.lucene;

import com.google.common.collect.AbstractIterator;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.util.BytesRef;
import org.apache.mahout.math.NamedVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.utils.Bump125;
import org.apache.mahout.utils.vectors.TermInfo;
import org.apache.mahout.vectorizer.Weight;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

/**
 * Iterate over a Lucene index, extracting term vectors.
 * Subclasses define how much information to retrieve from the Lucene index.
 */
public abstract class AbstractLuceneIterator extends AbstractIterator<Vector> {
    private static final Logger log = LoggerFactory.getLogger(LuceneIterator.class);
    protected final IndexReader indexReader;
    protected final String field;
    protected final TermInfo terminfo;
    protected final double normPower;
    protected final Weight weight;
    protected final Bump125 bump = new Bump125();
    protected int nextDocId;
    protected int maxErrorDocs;
    protected int numErrorDocs;
    protected long nextLogRecord = bump.increment();
    protected int skippedErrorMessages;

    public AbstractLuceneIterator(TermInfo terminfo, double normPower, IndexReader indexReader, Weight weight,
            double maxPercentErrorDocs, String field) {
        this.terminfo = terminfo;
        this.normPower = normPower;
        this.indexReader = indexReader;

        this.weight = weight;
        this.nextDocId = 0;
        this.maxErrorDocs = (int) (maxPercentErrorDocs * indexReader.numDocs());
        this.field = field;
    }

    /**
     * Given the document name, derive a name for the vector. This may involve
     * reading the document from Lucene and setting up any other state that the
     * subclass wants. This will be called once for each document that the
     * iterator processes.
     * @param documentIndex the lucene document index.
     * @return the name to store in the vector.
     */
    protected abstract String getVectorName(int documentIndex) throws IOException;

    @Override
    protected Vector computeNext() {
        try {
            int doc;
            Terms termFreqVector;
            String name;

            do {
                doc = this.nextDocId;
                nextDocId++;

                if (doc >= indexReader.maxDoc()) {
                    return endOfData();
                }

                termFreqVector = indexReader.getTermVector(doc, field);
                name = getVectorName(doc);

                if (termFreqVector == null) {
                    numErrorDocs++;
                    if (numErrorDocs >= maxErrorDocs) {
                        log.error("There are too many documents that do not have a term vector for {}", field);
                        throw new IllegalStateException(
                                "There are too many documents that do not have a term vector for " + field);
                    }
                    if (numErrorDocs >= nextLogRecord) {
                        if (skippedErrorMessages == 0) {
                            log.warn("{} does not have a term vector for {}", name, field);
                        } else {
                            log.warn("{} documents do not have a term vector for {}", numErrorDocs, field);
                        }
                        nextLogRecord = bump.increment();
                        skippedErrorMessages = 0;
                    } else {
                        skippedErrorMessages++;
                    }
                }
            } while (termFreqVector == null);

            // The loop exits with termFreqVector and name set.

            TermsEnum te = termFreqVector.iterator(null);
            BytesRef term;
            TFDFMapper mapper = new TFDFMapper(indexReader.numDocs(), weight, this.terminfo);
            mapper.setExpectations(field, termFreqVector.size());
            while ((term = te.next()) != null) {
                mapper.map(term, (int) te.totalTermFreq());
            }
            Vector result = mapper.getVector();
            if (result == null) {
                // TODO is this right? last version would produce null in the iteration in this case, though it
                // seems like that may not be desirable
                return null;
            }

            if (normPower == LuceneIterable.NO_NORMALIZING) {
                result = new NamedVector(result, name);
            } else {
                result = new NamedVector(result.normalize(normPower), name);
            }
            return result;
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }
}