/**
* 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.vectorizer.term;
import com.google.common.io.Closeables;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
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.CharTermAttribute;
import org.apache.mahout.common.HadoopUtil;
import org.apache.mahout.common.Pair;
import org.apache.mahout.common.StringTuple;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileIterable;
import org.apache.mahout.common.lucene.IteratorTokenStream;
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.vectorizer.DictionaryVectorizer;
import org.apache.mahout.vectorizer.common.PartialVectorMerger;
import java.io.IOException;
import java.util.Iterator;
/**
* 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 boolean namedVector;
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);
sf.reset();
try {
do {
String term = sf.getAttribute(CharTermAttribute.class).toString();
if (!term.isEmpty() && dictionary.containsKey(term)) { // ngram
int termId = dictionary.get(term);
vector.setQuick(termId, vector.getQuick(termId) + 1);
}
} while (sf.incrementToken());
sf.end();
} finally {
Closeables.close(sf, true);
}
} else {
for (String term : value.getEntries()) {
if (!term.isEmpty() && dictionary.containsKey(term)) { // unigram
int termId = dictionary.get(term);
vector.setQuick(termId, vector.getQuick(termId) + 1);
}
}
}
if (sequentialAccess) {
vector = new SequentialAccessSparseVector(vector);
}
if (namedVector) {
vector = new NamedVector(vector, key.toString());
}
// 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(vector);
context.write(key, vectorWritable);
} else {
context.getCounter("TFPartialVectorReducer", "emptyVectorCount").increment(1);
}
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
Configuration conf = context.getConfiguration();
dimension = conf.getInt(PartialVectorMerger.DIMENSION, Integer.MAX_VALUE);
sequentialAccess = conf.getBoolean(PartialVectorMerger.SEQUENTIAL_ACCESS, false);
namedVector = conf.getBoolean(PartialVectorMerger.NAMED_VECTOR, false);
maxNGramSize = conf.getInt(DictionaryVectorizer.MAX_NGRAMS, maxNGramSize);
//MAHOUT-1247
Path dictionaryFile = HadoopUtil.getSingleCachedFile(conf);
// key is word value is id
for (Pair<Writable, IntWritable> record
: new SequenceFileIterable<Writable, IntWritable>(dictionaryFile, true, conf)) {
dictionary.put(record.getFirst().toString(), record.getSecond().get());
}
}
}