pairsICSE15.1000021.CDbwReducer.1000021_CDbwReducer_s Maven / Gradle / Ivy
/**
* 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.clustering.cdbw;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.clustering.WeightedVectorWritable;
import org.apache.mahout.math.VectorWritable;
public class CDbwReducer extends Reducer {
private Map> referencePoints;
@Override
protected void cleanup(Context context) throws IOException, InterruptedException {
for (Map.Entry> entry : referencePoints.entrySet()) {
IntWritable iw = new IntWritable(entry.getKey());
for (VectorWritable vw : entry.getValue()) {
context.write(iw, vw);
}
}
super.cleanup(context);
}
@Override
protected void reduce(IntWritable key, Iterable values, Context context) throws IOException,
InterruptedException {
// find the most distant point
WeightedVectorWritable mdp = null;
for (WeightedVectorWritable dpw : values) {
if (mdp == null || mdp.getWeight() < dpw.getWeight()) {
mdp = new WeightedVectorWritable(dpw.getWeight(), dpw.getVector());
}
}
context.write(new IntWritable(key.get()), new VectorWritable(mdp.getVector()));
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
Configuration conf = context.getConfiguration();
try {
referencePoints = CDbwMapper.getRepresentativePoints(conf);
} catch (NumberFormatException e) {
throw new IllegalStateException(e);
} catch (SecurityException e) {
throw new IllegalStateException(e);
} catch (IllegalArgumentException e) {
throw new IllegalStateException(e);
}
}
public void configure(Map> referencePoints) {
this.referencePoints = referencePoints;
}
}