/**
* 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.tfidf;
import java.io.IOException;
import java.net.URI;
import java.util.Iterator;
import com.google.common.base.Preconditions;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.common.Pair;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileIterable;
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.OpenIntLongHashMap;
import org.apache.mahout.vectorizer.TFIDF;
import org.apache.mahout.vectorizer.common.PartialVectorMerger;
/**
* Converts a document in to a sparse vector
*/
public class TFIDFPartialVectorReducer extends
Reducer<WritableComparable<?>, VectorWritable, WritableComparable<?>, VectorWritable> {
private final OpenIntLongHashMap dictionary = new OpenIntLongHashMap();
private final TFIDF tfidf = new TFIDF();
private int minDf = 1;
private int maxDfPercent = 99;
private long vectorCount = 1;
private long featureCount;
private boolean sequentialAccess;
private boolean namedVector;
@Override
protected void reduce(WritableComparable<?> key, Iterable<VectorWritable> values, Context context)
throws IOException, InterruptedException {
Iterator<VectorWritable> it = values.iterator();
if (!it.hasNext()) {
return;
}
Vector value = it.next().get();
Iterator<Vector.Element> it1 = value.iterateNonZero();
Vector vector = new RandomAccessSparseVector((int) featureCount, value.getNumNondefaultElements());
while (it1.hasNext()) {
Vector.Element e = it1.next();
if (!dictionary.containsKey(e.index())) {
continue;
}
long df = dictionary.get(e.index());
if (df * 100.0 / vectorCount > maxDfPercent) {
continue;
}
if (df < minDf) {
df = minDf;
}
vector.setQuick(e.index(), tfidf.calculate((int) e.get(), (int) df, (int) featureCount, (int) vectorCount));
}
if (sequentialAccess) {
vector = new SequentialAccessSparseVector(vector);
}
if (namedVector) {
vector = new NamedVector(vector, key.toString());
}
VectorWritable vectorWritable = new VectorWritable(vector);
context.write(key, vectorWritable);
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
Configuration conf = context.getConfiguration();
URI[] localFiles = DistributedCache.getCacheFiles(conf);
Preconditions.checkArgument(localFiles != null && localFiles.length >= 1,
"missing paths from the DistributedCache");
vectorCount = conf.getLong(TFIDFConverter.VECTOR_COUNT, 1);
featureCount = conf.getLong(TFIDFConverter.FEATURE_COUNT, 1);
minDf = conf.getInt(TFIDFConverter.MIN_DF, 1);
maxDfPercent = conf.getInt(TFIDFConverter.MAX_DF_PERCENTAGE, 99);
sequentialAccess = conf.getBoolean(PartialVectorMerger.SEQUENTIAL_ACCESS, false);
namedVector = conf.getBoolean(PartialVectorMerger.NAMED_VECTOR, false);
Path dictionaryFile = new Path(localFiles[0].getPath());
// key is feature, value is the document frequency
for (Pair<IntWritable,LongWritable> record
: new SequenceFileIterable<IntWritable,LongWritable>(dictionaryFile, true, conf)) {
dictionary.put(record.getFirst().get(), record.getSecond().get());
}
}
}