/**
* 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.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.clustering.Cluster;
import org.apache.mahout.math.VectorWritable;
public class DirichletReducer extends Reducer<Text,VectorWritable,Text,DirichletCluster> {
private DirichletClusterer clusterer;
private Cluster[] newModels;
public Cluster[] getNewModels() {
return newModels;
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
DirichletState state = DirichletMapper.getDirichletState(context.getConfiguration());
clusterer = new DirichletClusterer(state);
List<DirichletCluster> oldModels = state.getClusters();
for (DirichletCluster cluster : oldModels) {
cluster.getModel().configure(context.getConfiguration());
}
this.newModels = (Cluster[]) state.getModelFactory().sampleFromPosterior(state.getModels());
for (Cluster cluster : newModels) {
cluster.configure(context.getConfiguration());
}
}
@Override
protected void reduce(Text key, Iterable<VectorWritable> values, Context context)
throws IOException, InterruptedException {
int k = Integer.parseInt(key.toString());
Cluster model = newModels[k];
for (VectorWritable value : values) {
// only observe real points, not the empty placeholders emitted by each mapper
if (value.get().size() > 0) {
model.observe(value);
}
}
DirichletCluster cluster = clusterer.updateCluster(model, k);
context.write(new Text(String.valueOf(k)), cluster);
}
public void setup(DirichletState state) {
clusterer = new DirichletClusterer(state);
List<DirichletCluster> oldModels = state.getClusters();
for (DirichletCluster cluster : oldModels) {
cluster.getModel().configure(new Configuration());
}
this.newModels = (Cluster[]) state.getModelFactory().sampleFromPosterior(state.getModels());
for (Cluster cluster : newModels) {
cluster.configure(new Configuration());
}
}
}