ivory.core.tokenize.DocumentProcessingUtils.java Source code

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Here is the source code for ivory.core.tokenize.DocumentProcessingUtils.java

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/*
 * Ivory: A Hadoop toolkit for web-scale information retrieval
 *
 * Licensed 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 ivory.core.tokenize;

import ivory.core.data.dictionary.Dictionary;
import ivory.core.data.document.TermDocVector;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedMap;

import org.apache.log4j.Logger;

import com.google.common.collect.Maps;

import edu.umd.cloud9.collection.Indexable;
import edu.umd.cloud9.util.array.ArrayListOfInts;

/**
 * @author Tamer Elsayed
 * @author Jimmy Lin
 */
public class DocumentProcessingUtils {
    private static final Logger LOG = Logger.getLogger(DocumentProcessingUtils.class);

    public static short TF_CUT = Short.MAX_VALUE;

    public static SortedMap<Integer, int[]> integerizeTermDocVector(TermDocVector doc, Dictionary termIDMap) {
        SortedMap<Integer, int[]> positions = Maps.newTreeMap();

        TermDocVector.Reader reader = null;
        try {
            reader = doc.getReader();
        } catch (IOException e1) {
            throw new RuntimeException("Error getting TermDocVectorReader: " + e1.getMessage());
        }

        while (reader.hasMoreTerms()) {
            int termid = termIDMap.getId(reader.nextTerm());
            if (termid <= 0) {
                continue;
            }

            positions.put(termid, reader.getPositions());
        }

        return positions;
    }

    public static Map<String, ArrayListOfInts> parseDocument(Indexable doc, Tokenizer tokenizer) {
        Map<String, ArrayListOfInts> positions = Maps.newHashMap();

        String text = doc.getContent();
        String[] terms = tokenizer.processContent(text);

        // The tokenizer may return terms with zero length (empty terms), and the tf may exceed the
        // capacity of a short (in which case we need to handle separately).

        for (int i = 0; i < terms.length; i++) {
            String term = terms[i];

            // Guard against bad tokenization
            if (term.length() == 0 || term.length() >= Byte.MAX_VALUE) {
                continue;
            }

            // Remember, token position is numbered started from one...
            if (positions.containsKey(term)) {
                positions.get(term).add(i + 1);
            } else {
                ArrayListOfInts l = new ArrayListOfInts();
                l.add(i + 1);
                positions.put(term, l);
            }
        }

        int doclength = 0;
        Iterator<Map.Entry<String, ArrayListOfInts>> it = positions.entrySet().iterator();
        Map.Entry<String, ArrayListOfInts> e;
        ArrayListOfInts positionsList;
        while (it.hasNext()) {
            e = it.next();
            positionsList = e.getValue();

            // We're storing tfs as shorts, so check for overflow...
            if (positionsList.size() >= TF_CUT) {
                // There are a few ways to handle this... If we're getting such a high tf, then it most
                // likely means that this is a junk doc.
                LOG.warn("Error: tf of " + e.getValue() + " will overflow max short value. docno=" + doc.getDocid()
                        + ", term=" + e.getKey());
                it.remove();
            } else {
                positionsList.trimToSize();
                doclength += positionsList.size();
            }
        }

        if (positions.size() == 0) {
            return positions;
        }

        // We're going to stick the doclength here as a special case.
        positions.put("", new ArrayListOfInts(new int[] { doclength }));
        return positions;
    }
}