/**
* 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 org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.clustering.dirichlet.models.DistributionDescription;
import org.apache.mahout.common.Pair;
import org.apache.mahout.common.iterator.sequencefile.PathFilters;
import org.apache.mahout.common.iterator.sequencefile.PathType;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileDirIterable;
import org.apache.mahout.math.DenseVector;
import org.apache.mahout.math.VectorWritable;
public class DirichletMapper extends Mapper<WritableComparable<?>, VectorWritable, Text, VectorWritable> {
private DirichletClusterer clusterer;
@Override
protected void map(WritableComparable<?> key, VectorWritable v, Context context)
throws IOException, InterruptedException {
int k = clusterer.assignToModel(v);
context.write(new Text(String.valueOf(k)), v);
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
DirichletState dirichletState = getDirichletState(context.getConfiguration());
for (DirichletCluster cluster : dirichletState.getClusters()) {
cluster.getModel().configure(context.getConfiguration());
}
clusterer = new DirichletClusterer(dirichletState);
for (int i = 0; i < dirichletState.getNumClusters(); i++) {
// write an empty vector to each clusterId so that all will be seen by a reducer
// Reducers will ignore these points but every model will be processed by one of them
context.write(new Text(Integer.toString(i)), new VectorWritable(new DenseVector(0)));
}
}
public void setup(DirichletState state) {
this.clusterer = new DirichletClusterer(state);
}
public static DirichletState getDirichletState(Configuration conf) {
String statePath = conf.get(DirichletDriver.STATE_IN_KEY);
String descriptionString = conf.get(DirichletDriver.MODEL_DISTRIBUTION_KEY);
String numClusters = conf.get(DirichletDriver.NUM_CLUSTERS_KEY);
String alpha0 = conf.get(DirichletDriver.ALPHA_0_KEY);
DistributionDescription description = DistributionDescription.fromString(descriptionString);
return loadState(conf, statePath, description, Double.parseDouble(alpha0), Integer.parseInt(numClusters));
}
protected static DirichletState loadState(Configuration conf,
String statePath,
DistributionDescription description,
double alpha,
int k) {
DirichletState state = DirichletDriver.createState(description, k, alpha);
Path path = new Path(statePath);
for (Pair<Writable,DirichletCluster> record
: new SequenceFileDirIterable<Writable,DirichletCluster>(path,
PathType.LIST,
PathFilters.logsCRCFilter(),
conf)) {
int index = Integer.parseInt(record.getFirst().toString());
state.getClusters().set(index, record.getSecond());
}
// TODO: with more than one mapper, they will all have different mixtures. Will this matter?
state.setMixture(UncommonDistributions.rDirichlet(state.totalCounts(), alpha));
return state;
}
}