/**
* 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.fuzzykmeans;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.mahout.matrix.AbstractVector;
import org.apache.mahout.matrix.Vector;
public class FuzzyKMeansReducer extends MapReduceBase implements
Reducer<Text, Text, Text, Text> {
protected Map<String, SoftCluster> clusterMap;
@Override
public void reduce(Text key, Iterator<Text> values,
OutputCollector<Text, Text> output, Reporter reporter) throws IOException {
SoftCluster cluster = clusterMap.get(key.toString());
while (values.hasNext()) {
String value = values.next().toString();
int mapperSepIndex = value
.indexOf(FuzzyKMeansDriver.MAPPER_VALUE_SEPARATOR); // tild separator
// is used in
// mapper
int combinerSepIndex = value
.indexOf(FuzzyKMeansDriver.COMBINER_VALUE_SEPARATOR); // tab separator
// is used in
// combiner
int index = mapperSepIndex == -1 ? combinerSepIndex : mapperSepIndex;// needed
// to
// split
// prob and vector
double partialSumPtProb = new Double(value.substring(0, index));
Vector total = AbstractVector.decodeVector(value.substring(index + 1));
if (mapperSepIndex != -1) // escaped from combiner
{
cluster.addPoint(total, Math.pow(partialSumPtProb, SoftCluster.getM()));
} else {
cluster.addPoints(total, partialSumPtProb);
}
}
// force convergence calculation
cluster.computeConvergence();
output.collect(new Text(cluster.getIdentifier()), new Text(SoftCluster
.formatCluster(cluster)));
}
@Override
public void configure(JobConf job) {
super.configure(job);
SoftCluster.configure(job);
clusterMap = new HashMap<String, SoftCluster>();
List<SoftCluster> clusters = new ArrayList<SoftCluster>();
FuzzyKMeansUtil.configureWithClusterInfo(job
.get(SoftCluster.CLUSTER_PATH_KEY), clusters);
setClusterMap(clusters);
if (clusterMap.isEmpty())
throw new NullPointerException("Cluster is empty!!!");
}
private void setClusterMap(List<SoftCluster> clusters) {
clusterMap = new HashMap<String, SoftCluster>();
for (SoftCluster cluster : clusters) {
clusterMap.put(cluster.getIdentifier(), cluster);
}
clusters.clear();
}
public void config(List<SoftCluster> clusters) {
setClusterMap(clusters);
}
}