/**
* 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.dirichlet;
import java.io.IOException;
import java.util.Iterator;
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.clustering.dirichlet.models.Model;
import org.apache.mahout.matrix.DenseVector;
import org.apache.mahout.matrix.Vector;
public class DirichletReducer extends MapReduceBase implements
Reducer<Text, Text, Text, Text> {
DirichletState<Vector> state;
public Model<Vector>[] newModels;
@Override
public void reduce(Text key, Iterator<Text> values,
OutputCollector<Text, Text> output, Reporter reporter) throws IOException {
Integer k = new Integer(key.toString());
Model<Vector> model = newModels[k];
while (values.hasNext()) {
Vector v = DenseVector.decodeFormat(values.next().toString());
model.observe(v);
}
model.computeParameters();
DirichletCluster<Vector> cluster = state.clusters.get(k);
cluster.setModel(model);
output.collect(key, new Text(cluster.asFormatString()));
}
public void configure(DirichletState<Vector> state) {
this.state = state;
this.newModels = state.modelFactory.sampleFromPosterior(state.getModels());
}
@Override
public void configure(JobConf job) {
super.configure(job);
state = DirichletMapper.getDirichletState(job);
this.newModels = state.modelFactory.sampleFromPosterior(state.getModels());
}
}