Example usage for org.apache.lucene.index Fields terms

List of usage examples for org.apache.lucene.index Fields terms

Introduction

In this page you can find the example usage for org.apache.lucene.index Fields terms.

Prototype

public abstract Terms terms(String field) throws IOException;

Source Link

Document

Get the Terms for this field.

Usage

From source file:com.github.flaxsearch.util.ReaderManager.java

License:Apache License

default TermsEnum findTermPostings(Integer segment, String field, String term) throws IOException {

    Fields fields = getFields(segment);
    Terms terms = fields.terms(field);

    if (terms == null) {
        String msg = String.format("No field %s", field);
        throw new WebApplicationException(msg, Response.Status.NOT_FOUND);
    }//from  ww w. ja v  a 2s . c o m

    TermsEnum te = terms.iterator();

    assert (term != null);
    if (!te.seekExact(new BytesRef(term))) {
        String msg = String.format("No term %s on field %s", term, field);
        throw new WebApplicationException(msg, Response.Status.NOT_FOUND);
    }

    return te;
}

From source file:com.o19s.solr.swan.highlight.SpanAwareFieldTermStack.java

License:Apache License

/**
 * a constructor.//from   ww  w .  j  a v  a 2  s  . com
 * 
 * @param reader IndexReader of the index
 * @param docId document id to be highlighted
 * @param fieldName field of the document to be highlighted
 * @param fieldQuery FieldQuery object
 * @throws IOException If there is a low-level I/O error
 */
public SpanAwareFieldTermStack(IndexReader reader, int docId, String fieldName,
        final SpanAwareFieldQuery fieldQuery) throws IOException {
    this.fieldName = fieldName;

    Set<String> termSet = fieldQuery.getTermSet(fieldName);
    Set<String> alwaysHighlightTermSet = fieldQuery.getHighlightTermSet(fieldName);

    // just return to make null snippet if un-matched fieldName specified when fieldMatch == true
    if (termSet == null)
        return;

    final Fields vectors = reader.getTermVectors(docId);
    if (vectors == null) {
        // null snippet
        return;
    }

    final Terms vector = vectors.terms(fieldName);
    if (vector == null) {
        // null snippet
        return;
    }

    final CharsRef spare = new CharsRef();
    final TermsEnum termsEnum = vector.iterator(null);
    DocsAndPositionsEnum dpEnum = null;
    BytesRef text;

    int numDocs = reader.maxDoc();
    while ((text = termsEnum.next()) != null) {
        UnicodeUtil.UTF8toUTF16(text, spare);
        final String term = spare.toString();
        if (!termSet.contains(term)) {
            continue;
        }
        dpEnum = termsEnum.docsAndPositions(null, dpEnum);
        if (dpEnum == null) {
            // null snippet
            return;
        }

        dpEnum.nextDoc();

        // For weight look here: http://lucene.apache.org/core/3_6_0/api/core/org/apache/lucene/search/DefaultSimilarity.html
        final float weight = (float) (Math
                .log(numDocs / (double) (reader.docFreq(new Term(fieldName, text)) + 1)) + 1.0);

        final int freq = dpEnum.freq();

        for (int i = 0; i < freq; i++) {
            int pos = dpEnum.nextPosition();
            if (dpEnum.startOffset() < 0) {
                return; // no offsets, null snippet
            }

            if (alwaysHighlightTermSet.contains(term)
                    || fieldQuery.doesDocFieldContainPosition(fieldName, docId, dpEnum.startOffset())) {
                termList.add(new TermInfo(term, dpEnum.startOffset(), dpEnum.endOffset(), pos, weight));
            }
        }

    }

    // sort by position
    Collections.sort(termList);
}

From source file:com.rocana.lucene.codec.v1.RocanaBasePostingsFormatTestCase.java

License:Apache License

@Override
public void testInvertedWrite() throws Exception {
    Directory dir = newDirectory();/*from  w  ww.  ja v a2s .co  m*/
    MockAnalyzer analyzer = new MockAnalyzer(random());
    analyzer.setMaxTokenLength(TestUtil.nextInt(random(), 1, IndexWriter.MAX_TERM_LENGTH));
    IndexWriterConfig iwc = newIndexWriterConfig(analyzer);

    // Must be concurrent because thread(s) can be merging
    // while up to one thread flushes, and each of those
    // threads iterates over the map while the flushing
    // thread might be adding to it:
    final Map<String, TermFreqs> termFreqs = new ConcurrentHashMap<>();

    final AtomicLong sumDocFreq = new AtomicLong();
    final AtomicLong sumTotalTermFreq = new AtomicLong();

    // TODO: would be better to use / delegate to the current
    // Codec returned by getCodec()

    iwc.setCodec(new AssertingCodec() {
        @Override
        public PostingsFormat getPostingsFormatForField(String field) {

            PostingsFormat p = getCodec().postingsFormat();
            if (p instanceof PerFieldPostingsFormat) {
                p = ((PerFieldPostingsFormat) p).getPostingsFormatForField(field);
            }
            if (p instanceof RocanaPerFieldPostingsFormat) {
                p = ((RocanaPerFieldPostingsFormat) p).getPostingsFormatForField(field);
            }
            final PostingsFormat defaultPostingsFormat = p;

            final Thread mainThread = Thread.currentThread();

            if (field.equals("body")) {

                // A PF that counts up some stats and then in
                // the end we verify the stats match what the
                // final IndexReader says, just to exercise the
                // new freedom of iterating the postings more
                // than once at flush/merge:

                return new PostingsFormat(defaultPostingsFormat.getName()) {

                    @Override
                    public FieldsConsumer fieldsConsumer(final SegmentWriteState state) throws IOException {

                        final FieldsConsumer fieldsConsumer = defaultPostingsFormat.fieldsConsumer(state);

                        return new FieldsConsumer() {
                            @Override
                            public void write(Fields fields) throws IOException {
                                fieldsConsumer.write(fields);

                                boolean isMerge = state.context.context == IOContext.Context.MERGE;

                                // We only use one thread for flushing
                                // in this test:
                                assert isMerge || Thread.currentThread() == mainThread;

                                // We iterate the provided TermsEnum
                                // twice, so we excercise this new freedom
                                // with the inverted API; if
                                // addOnSecondPass is true, we add up
                                // term stats on the 2nd iteration:
                                boolean addOnSecondPass = random().nextBoolean();

                                //System.out.println("write isMerge=" + isMerge + " 2ndPass=" + addOnSecondPass);

                                // Gather our own stats:
                                Terms terms = fields.terms("body");
                                assert terms != null;

                                TermsEnum termsEnum = terms.iterator();
                                PostingsEnum docs = null;
                                while (termsEnum.next() != null) {
                                    BytesRef term = termsEnum.term();
                                    // TODO: also sometimes ask for payloads/offsets?
                                    boolean noPositions = random().nextBoolean();
                                    if (noPositions) {
                                        docs = termsEnum.postings(docs, PostingsEnum.FREQS);
                                    } else {
                                        docs = termsEnum.postings(null, PostingsEnum.POSITIONS);
                                    }
                                    int docFreq = 0;
                                    long totalTermFreq = 0;
                                    while (docs.nextDoc() != PostingsEnum.NO_MORE_DOCS) {
                                        docFreq++;
                                        totalTermFreq += docs.freq();
                                        int limit = TestUtil.nextInt(random(), 1, docs.freq());
                                        if (!noPositions) {
                                            for (int i = 0; i < limit; i++) {
                                                docs.nextPosition();
                                            }
                                        }
                                    }

                                    String termString = term.utf8ToString();

                                    // During merge we should only see terms
                                    // we had already seen during a
                                    // previous flush:
                                    assertTrue(isMerge == false || termFreqs.containsKey(termString));

                                    if (isMerge == false) {
                                        if (addOnSecondPass == false) {
                                            TermFreqs tf = termFreqs.get(termString);
                                            if (tf == null) {
                                                tf = new TermFreqs();
                                                termFreqs.put(termString, tf);
                                            }
                                            tf.docFreq += docFreq;
                                            tf.totalTermFreq += totalTermFreq;
                                            sumDocFreq.addAndGet(docFreq);
                                            sumTotalTermFreq.addAndGet(totalTermFreq);
                                        } else if (termFreqs.containsKey(termString) == false) {
                                            // Add placeholder (2nd pass will
                                            // set its counts):
                                            termFreqs.put(termString, new TermFreqs());
                                        }
                                    }
                                }

                                // Also test seeking the TermsEnum:
                                for (String term : termFreqs.keySet()) {
                                    if (termsEnum.seekExact(new BytesRef(term))) {
                                        // TODO: also sometimes ask for payloads/offsets?
                                        boolean noPositions = random().nextBoolean();
                                        if (noPositions) {
                                            docs = termsEnum.postings(docs, PostingsEnum.FREQS);
                                        } else {
                                            docs = termsEnum.postings(null, PostingsEnum.POSITIONS);
                                        }

                                        int docFreq = 0;
                                        long totalTermFreq = 0;
                                        while (docs.nextDoc() != PostingsEnum.NO_MORE_DOCS) {
                                            docFreq++;
                                            totalTermFreq += docs.freq();
                                            int limit = TestUtil.nextInt(random(), 1, docs.freq());
                                            if (!noPositions) {
                                                for (int i = 0; i < limit; i++) {
                                                    docs.nextPosition();
                                                }
                                            }
                                        }

                                        if (isMerge == false && addOnSecondPass) {
                                            TermFreqs tf = termFreqs.get(term);
                                            assert tf != null;
                                            tf.docFreq += docFreq;
                                            tf.totalTermFreq += totalTermFreq;
                                            sumDocFreq.addAndGet(docFreq);
                                            sumTotalTermFreq.addAndGet(totalTermFreq);
                                        }

                                        //System.out.println("  term=" + term + " docFreq=" + docFreq + " ttDF=" + termToDocFreq.get(term));
                                        assertTrue(docFreq <= termFreqs.get(term).docFreq);
                                        assertTrue(totalTermFreq <= termFreqs.get(term).totalTermFreq);
                                    }
                                }

                                // Also test seekCeil
                                for (int iter = 0; iter < 10; iter++) {
                                    BytesRef term = new BytesRef(
                                            TestUtil.randomRealisticUnicodeString(random()));
                                    SeekStatus status = termsEnum.seekCeil(term);
                                    if (status == SeekStatus.NOT_FOUND) {
                                        assertTrue(term.compareTo(termsEnum.term()) < 0);
                                    }
                                }
                            }

                            @Override
                            public void close() throws IOException {
                                fieldsConsumer.close();
                            }
                        };
                    }

                    @Override
                    public FieldsProducer fieldsProducer(SegmentReadState state) throws IOException {
                        return defaultPostingsFormat.fieldsProducer(state);
                    }
                };
            } else {
                return defaultPostingsFormat;
            }
        }
    });

    RandomIndexWriter w = new RandomIndexWriter(random(), dir, iwc);

    LineFileDocs docs = new LineFileDocs(random());
    int bytesToIndex = atLeast(100) * 1024;
    int bytesIndexed = 0;
    while (bytesIndexed < bytesToIndex) {
        Document doc = docs.nextDoc();
        w.addDocument(doc);
        bytesIndexed += RamUsageTester.sizeOf(doc);
    }

    IndexReader r = w.getReader();
    w.close();

    Terms terms = MultiFields.getTerms(r, "body");
    assertEquals(sumDocFreq.get(), terms.getSumDocFreq());
    assertEquals(sumTotalTermFreq.get(), terms.getSumTotalTermFreq());

    TermsEnum termsEnum = terms.iterator();
    long termCount = 0;
    boolean supportsOrds = true;
    while (termsEnum.next() != null) {
        BytesRef term = termsEnum.term();
        assertEquals(termFreqs.get(term.utf8ToString()).docFreq, termsEnum.docFreq());
        assertEquals(termFreqs.get(term.utf8ToString()).totalTermFreq, termsEnum.totalTermFreq());
        if (supportsOrds) {
            long ord;
            try {
                ord = termsEnum.ord();
            } catch (UnsupportedOperationException uoe) {
                supportsOrds = false;
                ord = -1;
            }
            if (ord != -1) {
                assertEquals(termCount, ord);
            }
        }
        termCount++;
    }
    assertEquals(termFreqs.size(), termCount);

    r.close();
    dir.close();
}

From source file:com.senseidb.abacus.api.codec.CodecTest.java

License:Apache License

static void testThreaded(int numThreads, final int numIter, final AtomicReader reader, final String field) {
    Runnable runnable = new Runnable() {
        public void run() {
            try {
                Fields f = reader.fields();
                Terms t = f.terms(field);

                TermsEnum te = t.iterator(null);

                ArrayList<BytesRef> termList = new ArrayList<BytesRef>();

                BytesRef termText;// ww  w.ja va  2 s  . c  o  m
                while ((termText = te.next()) != null) {
                    termList.add(termText);
                }

                Random rand = new Random();

                for (int i = 0; i < numIter; ++i) {
                    int idx = rand.nextInt(termList.size());
                    termText = termList.get(idx);
                    te = t.iterator(null);
                    te.seekCeil(termText);
                    DocsEnum de = te.docs(null, null);
                    int doc;
                    while ((doc = de.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
                    }

                    de = te.docs(null, null);
                    doc = -1;
                    while ((doc = de.advance(doc + 2)) != DocIdSetIterator.NO_MORE_DOCS) {
                    }
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    };

    Thread[] threads = new Thread[numThreads];
    for (int i = 0; i < numThreads; ++i) {
        threads[i] = new Thread(runnable);
    }
    for (int i = 0; i < numThreads; ++i) {
        threads[i].start();
    }
    for (int i = 0; i < numThreads; ++i) {
        try {
            threads[i].join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

From source file:com.sindicetech.siren.search.node.NodeTermCollectingRewrite.java

License:Open Source License

final void collectTerms(final IndexReader reader, final MultiNodeTermQuery query, final TermCollector collector)
        throws IOException {
    final IndexReaderContext topReaderContext = reader.getContext();
    Comparator<BytesRef> lastTermComp = null;
    for (final AtomicReaderContext context : topReaderContext.leaves()) {
        final Fields fields = context.reader().fields();
        if (fields == null) {
            // reader has no fields
            continue;
        }/*  ww w .ja v a  2 s. c  o  m*/

        final Terms terms = fields.terms(query.field);
        if (terms == null) {
            // field does not exist
            continue;
        }

        final TermsEnum termsEnum = this.getTermsEnum(query, terms, collector.attributes);
        assert termsEnum != null;

        if (termsEnum == TermsEnum.EMPTY)
            continue;

        // Check comparator compatibility:
        final Comparator<BytesRef> newTermComp = termsEnum.getComparator();
        if (lastTermComp != null && newTermComp != null && newTermComp != lastTermComp)
            throw new RuntimeException("term comparator should not change between segments: " + lastTermComp
                    + " != " + newTermComp);
        lastTermComp = newTermComp;
        collector.setReaderContext(topReaderContext, context);
        collector.setNextEnum(termsEnum);
        BytesRef bytes;
        while ((bytes = termsEnum.next()) != null) {
            if (!collector.collect(bytes))
                return; // interrupt whole term collection, so also don't iterate other subReaders
        }
    }
}

From source file:de.tuberlin.dima.cuttlefish.preprocessing.vectorization.Vectorizer.java

License:Open Source License

public void vectorize(File luceneIndexDir, File outputDir) throws Exception {

    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.getLocal(conf);
    SequenceFile.Writer writer = null;

    FeatureDictionary dict = new FeatureDictionary();

    DirectoryReader reader = null;/*from  ww  w.j  av a2s  . c  o m*/
    try {
        reader = DirectoryReader.open(new SimpleFSDirectory(luceneIndexDir));

        writer = SequenceFile.createWriter(fs, conf, new Path(outputDir.toString(), "documentVectors.seq"),
                IDAndCodes.class, VectorWritable.class);
        IDAndCodes idAndCodes = new IDAndCodes();
        VectorWritable vectorWritable = new VectorWritable();

        Fields fields = MultiFields.getFields(reader);
        if (fields != null) {
            Iterator<String> fieldNames = fields.iterator();
            while (fieldNames.hasNext()) {
                String field = fieldNames.next();
                if (!field.startsWith("bip:") && !"itemID".equals(field)) {

                    Terms terms = fields.terms(field);
                    TermsEnum termsEnum = terms.iterator(null);
                    BytesRef text;
                    while ((text = termsEnum.next()) != null) {
                        dict.addTextFeature(field, text.utf8ToString());
                    }
                }
            }
        }

        int numDocsVectorized = 0;

        for (int docID = 0; docID < reader.maxDoc(); docID++) {
            Document doc = reader.document(docID);

            int itemID = doc.getField("itemID").numericValue().intValue();

            RandomAccessSparseVector documentVector = new RandomAccessSparseVector(dict.numFeatures());
            Multimap<String, String> codes = HashMultimap.create();

            for (IndexableField field : doc.getFields()) {

                String fieldName = field.name();

                if (!fieldName.startsWith("bip:") && !"itemID".equals(fieldName)) {

                    Terms termFreqVector = reader.getTermVector(docID, fieldName);

                    if (termFreqVector != null) {

                        int maxTermFrequency = maxTermFrequency(termFreqVector);

                        TermsEnum te = termFreqVector.iterator(null);
                        BytesRef term;

                        while ((term = te.next()) != null) {

                            String termStr = term.utf8ToString();
                            int termFrequency = (int) te.totalTermFreq();

                            int documentFrequency = reader.docFreq(new Term(fieldName, term));
                            int numDocs = reader.numDocs();

                            double weight = weighting.weight(fieldName, termStr, termFrequency,
                                    documentFrequency, maxTermFrequency, numDocs);

                            int featureIndex = dict.index(fieldName, term.utf8ToString());
                            documentVector.setQuick(featureIndex, weight);
                        }
                    }

                } else if (fieldName.startsWith("bip:")) {
                    for (String value : doc.getValues(fieldName)) {
                        codes.put(fieldName, value);
                    }
                }
            }

            Vector featureVector = new SequentialAccessSparseVector(documentVector);

            weighting.normalize(featureVector);

            idAndCodes.set(itemID, codes);
            vectorWritable.set(featureVector);
            writer.append(idAndCodes, vectorWritable);

            numDocsVectorized++;
            if (numDocsVectorized % 100 == 0) {
                log.info("Vectorized {} documents", numDocsVectorized);
            }
        }

        log.info("Vectorized {} documents", numDocsVectorized);

        dict.writeToFile(new File(outputDir, "features.txt"));

        log.info("Wrote feature dictionary");

    } finally {
        Closeables.close(reader, true);
        Closeables.close(writer, true);
    }

}

From source file:de.tudarmstadt.ukp.dkpro.tc.features.ngram.base.LuceneFeatureExtractorBase.java

License:Apache License

@Override
protected FrequencyDistribution<String> getTopNgrams() throws ResourceInitializationException {

    FrequencyDistribution<String> topNGrams = new FrequencyDistribution<String>();

    MinMaxPriorityQueue<TermFreqTuple> topN = MinMaxPriorityQueue.maximumSize(getTopN()).create();

    long ngramVocabularySize = 0;
    IndexReader reader;//w  w w .j av a  2 s .  com
    try {
        reader = DirectoryReader.open(FSDirectory.open(luceneDir));
        Fields fields = MultiFields.getFields(reader);
        if (fields != null) {
            Terms terms = fields.terms(getFieldName());
            if (terms != null) {
                TermsEnum termsEnum = terms.iterator(null);
                BytesRef text = null;
                while ((text = termsEnum.next()) != null) {
                    String term = text.utf8ToString();
                    long freq = termsEnum.totalTermFreq();
                    if (passesScreening(term)) {
                        topN.add(new TermFreqTuple(term, freq));
                        ngramVocabularySize += freq;
                    }
                }
            }
        }
    } catch (Exception e) {
        throw new ResourceInitializationException(e);
    }

    int size = topN.size();
    for (int i = 0; i < size; i++) {
        TermFreqTuple tuple = topN.poll();
        long absCount = tuple.getFreq();
        double relFrequency = ((double) absCount) / ngramVocabularySize;

        if (relFrequency >= ngramFreqThreshold) {
            topNGrams.addSample(tuple.getTerm(), tuple.getFreq());
        }
    }

    logSelectionProcess(topNGrams.getB());

    return topNGrams;
}

From source file:de.tudarmstadt.ukp.dkpro.tc.features.ngram.meta.LuceneNGramMetaCollectorTest.java

License:Apache License

@Test
public void luceneNgramMetaCollectorTest() throws Exception {
    File tmpDir = folder.newFolder();

    CollectionReaderDescription reader = CollectionReaderFactory.createReaderDescription(TextReader.class,
            TextReader.PARAM_SOURCE_LOCATION, "src/test/resources/data/", TextReader.PARAM_LANGUAGE, "en",
            TextReader.PARAM_PATTERNS, "text*.txt");

    AnalysisEngineDescription segmenter = AnalysisEngineFactory
            .createEngineDescription(BreakIteratorSegmenter.class);

    AnalysisEngineDescription metaCollector = AnalysisEngineFactory
            .createEngineDescription(LuceneNGramMetaCollector.class, LuceneNGramDFE.PARAM_LUCENE_DIR, tmpDir);

    for (JCas jcas : new JCasIterable(reader, segmenter, metaCollector)) {
        //            System.out.println(jcas.getDocumentText().length());
    }/*ww  w . ja v  a 2 s.c om*/

    int i = 0;
    IndexReader index;
    try {
        index = DirectoryReader.open(FSDirectory.open(tmpDir));
        Fields fields = MultiFields.getFields(index);
        if (fields != null) {
            Terms terms = fields.terms(LuceneNGramDFE.LUCENE_NGRAM_FIELD);
            if (terms != null) {
                TermsEnum termsEnum = terms.iterator(null);
                //                    Bits liveDocs = MultiFields.getLiveDocs(index);
                //                    DocsEnum docs = termsEnum.docs(liveDocs, null);
                //                    int docId;
                //                    while((docId = docs.nextDoc()) != DocsEnum.NO_MORE_DOCS) {
                //                        index.g
                //                    }
                BytesRef text = null;
                while ((text = termsEnum.next()) != null) {
                    //                        System.out.println(text.utf8ToString() + " - " + termsEnum.totalTermFreq());
                    //                        System.out.println(termsEnum.docFreq());

                    if (text.utf8ToString().equals("this")) {
                        assertEquals(2, termsEnum.docFreq());
                        assertEquals(3, termsEnum.totalTermFreq());
                    }

                    i++;
                }
            }
        }
    } catch (Exception e) {
        throw new ResourceInitializationException(e);
    }

    assertEquals(35, i);
}

From source file:de.tudarmstadt.ukp.dkpro.tc.features.pair.core.ngram.LuceneNGramCPFE.java

License:Apache License

private FrequencyDistribution<String> getTopNgramsCombo(int topNgramThreshold, String fieldName)
        throws ResourceInitializationException {

    FrequencyDistribution<String> topNGrams = new FrequencyDistribution<String>();

    MinMaxPriorityQueue<TermFreqTuple> topN = MinMaxPriorityQueue.maximumSize(topNgramThreshold).create();
    IndexReader reader;// w w w .  jav a  2  s .com
    try {
        reader = DirectoryReader.open(FSDirectory.open(luceneDir));
        Fields fields = MultiFields.getFields(reader);
        if (fields != null) {
            Terms terms = fields.terms(fieldName);
            if (terms != null) {
                TermsEnum termsEnum = terms.iterator(null);
                BytesRef text = null;
                while ((text = termsEnum.next()) != null) {
                    String term = text.utf8ToString();
                    long freq = termsEnum.totalTermFreq();
                    //add conditions here, like ngram1 is in most freq ngrams1...
                    String combo1 = term.split(ComboUtils.JOINT)[0];
                    String combo2 = term.split(ComboUtils.JOINT)[1];
                    int combinedSize = combo1.split("_").length + combo2.split("_").length;
                    if (topKSetView1.contains(combo1) && topKSet.contains(combo1)
                            && topKSetView2.contains(combo2) && topKSet.contains(combo2)
                            && combinedSize <= ngramMaxNCombo && combinedSize >= ngramMinNCombo) {
                        //print out here for testing
                        topN.add(new TermFreqTuple(term, freq));
                    }
                }
            }
        }
    } catch (Exception e) {
        throw new ResourceInitializationException(e);
    }

    int size = topN.size();
    for (int i = 0; i < size; i++) {
        TermFreqTuple tuple = topN.poll();
        // System.out.println(tuple.getTerm() + " - " + tuple.getFreq());
        topNGrams.addSample(tuple.getTerm(), tuple.getFreq());
    }

    return topNGrams;
}

From source file:de.tudarmstadt.ukp.dkpro.tc.features.pair.core.ngram.LuceneNGramPFE.java

License:Apache License

private FrequencyDistribution<String> getTopNgrams(int topNgramThreshold, String fieldName)
        throws ResourceInitializationException {

    FrequencyDistribution<String> topNGrams = new FrequencyDistribution<String>();

    MinMaxPriorityQueue<TermFreqTuple> topN = MinMaxPriorityQueue.maximumSize(topNgramThreshold).create();
    IndexReader reader;/* w w  w. j  av  a 2 s  . c  o m*/
    try {
        reader = DirectoryReader.open(FSDirectory.open(luceneDir));
        Fields fields = MultiFields.getFields(reader);
        if (fields != null) {
            Terms terms = fields.terms(fieldName);
            if (terms != null) {
                TermsEnum termsEnum = terms.iterator(null);
                BytesRef text = null;
                while ((text = termsEnum.next()) != null) {
                    String term = text.utf8ToString();
                    long freq = termsEnum.totalTermFreq();
                    topN.add(new TermFreqTuple(term, freq));
                }
            }
        }
    } catch (Exception e) {
        throw new ResourceInitializationException(e);
    }

    int size = topN.size();
    for (int i = 0; i < size; i++) {
        TermFreqTuple tuple = topN.poll();
        // System.out.println(tuple.getTerm() + " - " + tuple.getFreq());
        topNGrams.addSample(tuple.getTerm(), tuple.getFreq());
    }

    return topNGrams;
}