org.apache.mahout.vectorizer.pruner.WordsPrunerReducer Maven / Gradle / Ivy
package org.apache.mahout.vectorizer.pruner;
/**
* 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.
*/
import org.apache.hadoop.conf.Configuration;
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.HadoopUtil;
import org.apache.mahout.common.Pair;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileIterable;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import org.apache.mahout.math.map.OpenIntLongHashMap;
import org.apache.mahout.vectorizer.HighDFWordsPruner;
import java.io.IOException;
import java.util.Iterator;
public class WordsPrunerReducer extends
Reducer, VectorWritable, WritableComparable, VectorWritable> {
private final OpenIntLongHashMap dictionary = new OpenIntLongHashMap();
private long maxDf = Long.MAX_VALUE;
private long minDf = -1;
@Override
protected void reduce(WritableComparable key, Iterable values, Context context)
throws IOException, InterruptedException {
Iterator it = values.iterator();
if (!it.hasNext()) {
return;
}
Vector value = it.next().get();
Vector vector = value.clone();
if (maxDf != Long.MAX_VALUE || minDf > -1) {
for (Vector.Element e : value.nonZeroes()) {
if (!dictionary.containsKey(e.index())) {
vector.setQuick(e.index(), 0.0);
continue;
}
long df = dictionary.get(e.index());
if (df > maxDf || df < minDf) {
vector.setQuick(e.index(), 0.0);
}
}
}
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();
//Path[] localFiles = HadoopUtil.getCachedFiles(conf);
maxDf = conf.getLong(HighDFWordsPruner.MAX_DF, Long.MAX_VALUE);
minDf = conf.getLong(HighDFWordsPruner.MIN_DF, -1);
Path dictionaryFile = HadoopUtil.getSingleCachedFile(conf);
// key is feature, value is the document frequency
for (Pair record
: new SequenceFileIterable(dictionaryFile, true, conf)) {
dictionary.put(record.getFirst().get(), record.getSecond().get());
}
}
}