org.apache.mahout.utils.vectors.text.term.TFPartialVectorReducer.java Source code

Introduction

Here is the source code for org.apache.mahout.utils.vectors.text.term.TFPartialVectorReducer.java

Source

/**
 * 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.text.term;

import java.io.IOException;
import java.net.URI;
import java.util.Iterator;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.lucene.analysis.shingle.ShingleFilter;
import org.apache.lucene.analysis.tokenattributes.TermAttribute;
import org.apache.mahout.common.StringTuple;
import org.apache.mahout.math.NamedVector;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.SequentialAccessSparseVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import org.apache.mahout.math.map.OpenObjectIntHashMap;
import org.apache.mahout.utils.nlp.collocations.llr.CollocMapper.IteratorTokenStream;
import org.apache.mahout.utils.vectors.common.PartialVectorMerger;
import org.apache.mahout.utils.vectors.text.DictionaryVectorizer;

/**
 * Converts a document in to a sparse vector
 */
public class TFPartialVectorReducer extends Reducer<Text, StringTuple, Text, VectorWritable> {

    private final OpenObjectIntHashMap<String> dictionary = new OpenObjectIntHashMap<String>();

    private int dimension;

    private boolean sequentialAccess;

    private int maxNGramSize = 1;

    @Override
    protected void reduce(Text key, Iterable<StringTuple> values, Context context)
            throws IOException, InterruptedException {
        Iterator<StringTuple> it = values.iterator();
        if (!it.hasNext()) {
            return;
        }
        StringTuple value = it.next();

        Vector vector = new RandomAccessSparseVector(dimension, value.length()); // guess at initial size

        if (maxNGramSize >= 2) {
            ShingleFilter sf = new ShingleFilter(new IteratorTokenStream(value.getEntries().iterator()),
                    maxNGramSize);

            do {
                String term = (sf.getAttribute(TermAttribute.class)).term();
                if (term.length() > 0) { // ngram
                    if (dictionary.containsKey(term)) {
                        int termId = dictionary.get(term);
                        vector.setQuick(termId, vector.getQuick(termId) + 1);
                    }
                }
            } while (sf.incrementToken());

            sf.end();
            sf.close();
        } else {
            for (String term : value.getEntries()) {
                if (term.length() > 0) { // unigram
                    if (dictionary.containsKey(term)) {
                        int termId = dictionary.get(term);
                        vector.setQuick(termId, vector.getQuick(termId) + 1);
                    }
                }
            }
        }
        if (sequentialAccess) {
            vector = new SequentialAccessSparseVector(vector);
        }
        // if the vector has no nonZero entries (nothing in the dictionary), let's not waste space sending it to disk.
        if (vector.getNumNondefaultElements() > 0) {
            VectorWritable vectorWritable = new VectorWritable(new NamedVector(vector, key.toString()));
            context.write(key, vectorWritable);
        } else {
            context.getCounter("TFParticalVectorReducer", "emptyVectorCount").increment(1);
        }
    }

    @Override
    protected void setup(Context context) throws IOException, InterruptedException {
        super.setup(context);
        Configuration conf = context.getConfiguration();
        try {
            dimension = conf.getInt(PartialVectorMerger.DIMENSION, Integer.MAX_VALUE);
            sequentialAccess = conf.getBoolean(PartialVectorMerger.SEQUENTIAL_ACCESS, false);
            maxNGramSize = conf.getInt(DictionaryVectorizer.MAX_NGRAMS, maxNGramSize);
            URI[] localFiles = DistributedCache.getCacheFiles(conf);
            if (localFiles == null || localFiles.length < 1) {
                throw new IllegalArgumentException("missing paths from the DistributedCache");
            }
            Path dictionaryFile = new Path(localFiles[0].getPath());
            FileSystem fs = dictionaryFile.getFileSystem(conf);
            SequenceFile.Reader reader = new SequenceFile.Reader(fs, dictionaryFile, conf);
            Writable key = new Text();
            IntWritable value = new IntWritable();

            // key is word value is id
            while (reader.next(key, value)) {
                dictionary.put(key.toString(), value.get());
            }
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
    }

}