/**
* 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.classifier.df.mapreduce.inmem;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.mahout.classifier.df.DFUtils;
import org.apache.mahout.classifier.df.DecisionForest;
import org.apache.mahout.classifier.df.builder.TreeBuilder;
import org.apache.mahout.classifier.df.mapreduce.Builder;
import org.apache.mahout.classifier.df.mapreduce.MapredOutput;
import org.apache.mahout.classifier.df.node.Node;
import org.apache.mahout.common.Pair;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileIterable;
import java.io.IOException;
import java.util.List;
import java.util.Map;
/**
* MapReduce implementation where each mapper loads a full copy of the data in-memory. The forest trees are
* splitted across all the mappers
*/
public class InMemBuilder extends Builder {
public InMemBuilder(TreeBuilder treeBuilder, Path dataPath, Path datasetPath, Long seed, Configuration conf) {
super(treeBuilder, dataPath, datasetPath, seed, conf);
}
public InMemBuilder(TreeBuilder treeBuilder, Path dataPath, Path datasetPath) {
this(treeBuilder, dataPath, datasetPath, null, new Configuration());
}
@Override
protected void configureJob(Job job) throws IOException {
Configuration conf = job.getConfiguration();
job.setJarByClass(InMemBuilder.class);
FileOutputFormat.setOutputPath(job, getOutputPath(conf));
// put the data in the DistributedCache
DistributedCache.addCacheFile(getDataPath().toUri(), conf);
job.setOutputKeyClass(IntWritable.class);
job.setOutputValueClass(MapredOutput.class);
job.setMapperClass(InMemMapper.class);
job.setNumReduceTasks(0); // no reducers
job.setInputFormatClass(InMemInputFormat.class);
job.setOutputFormatClass(SequenceFileOutputFormat.class);
}
@Override
protected DecisionForest parseOutput(Job job) throws IOException {
Configuration conf = job.getConfiguration();
Map<Integer,MapredOutput> output = Maps.newHashMap();
Path outputPath = getOutputPath(conf);
FileSystem fs = outputPath.getFileSystem(conf);
Path[] outfiles = DFUtils.listOutputFiles(fs, outputPath);
// import the InMemOutputs
for (Path path : outfiles) {
for (Pair<IntWritable,MapredOutput> record : new SequenceFileIterable<IntWritable,MapredOutput>(path, conf)) {
output.put(record.getFirst().get(), record.getSecond());
}
}
return processOutput(output);
}
/**
* Process the output, extracting the trees
*/
private static DecisionForest processOutput(Map<Integer,MapredOutput> output) {
List<Node> trees = Lists.newArrayList();
for (Map.Entry<Integer,MapredOutput> entry : output.entrySet()) {
MapredOutput value = entry.getValue();
trees.add(value.getTree());
}
return new DecisionForest(trees);
}
}