org.apache.mahout.clustering.topdown.postprocessor.ClusterOutputPostProcessorReducer 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.topdown.postprocessor;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.VectorWritable;
import java.io.IOException;
import java.util.Map;
/**
* Reducer for post processing cluster output.
*/
public class ClusterOutputPostProcessorReducer
extends Reducer {
private Map reverseClusterMappings;
//read the current cluster ids, and populate the hash cluster mapping hash table
@Override
public void setup(Context context) throws IOException {
Configuration conf = context.getConfiguration();
Path clusterOutputPath = new Path(conf.get("clusterOutputPath"));
//we want to the key to be the index, the value to be the cluster id
reverseClusterMappings = ClusterCountReader.getClusterIDs(clusterOutputPath, conf, false);
}
/**
* The key is the remapped cluster id and the values contains the vectors in that cluster.
*/
@Override
protected void reduce(IntWritable key, Iterable values, Context context) throws IOException,
InterruptedException {
//remap the cluster back to its original id
//and then output the vectors with their correct
//cluster id.
IntWritable outKey = new IntWritable(reverseClusterMappings.get(key.get()));
System.out.println(outKey + " this: " + this);
for (VectorWritable value : values) {
context.write(outKey, value);
}
}
}