/**
* 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.ga.watchmaker;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.SequenceFile.Reader;
import org.apache.hadoop.io.SequenceFile.Sorter;
import org.apache.hadoop.mapred.JobConf;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/** Utility Class that deals with the output. */
public final class OutputUtils {
private OutputUtils() {
// do nothing
}
/**
* Removes the output directory if it already exists.
*
* @param fs <code>FileSystem</code> to use
* @return output <code>Path</code>
*/
public static Path prepareOutput(FileSystem fs) throws IOException {
Path outpath = new Path(fs.getWorkingDirectory(), "output");
if (fs.exists(outpath)) {
fs.delete(outpath, true);
}
return outpath;
}
/**
* Lists all files in the output <code>Path</code>
*
* @param fs <code>FileSystem</code> to use
* @param outpath output <code>Path</code>
* @return <code>Path</code> array
*/
public static Path[] listOutputFiles(FileSystem fs, Path outpath)
throws IOException {
FileStatus[] status = fs.listStatus(outpath);
List<Path> outpaths = new ArrayList<Path>();
for (FileStatus s : status) {
if (!s.isDir()) {
outpaths.add(s.getPath());
}
}
Path[] outfiles = new Path[outpaths.size()];
outpaths.toArray(outfiles);
return outfiles;
}
/**
* Reads back the evaluations.
*
* @param outpath output <code>Path</code>
* @param evaluations List of evaluations
*/
public static void importEvaluations(FileSystem fs, JobConf conf,
Path outpath, List<Double> evaluations) throws IOException {
Sorter sorter = new Sorter(fs, LongWritable.class, DoubleWritable.class, conf);
// merge and sort the outputs
Path[] outfiles = listOutputFiles(fs, outpath);
Path output = new Path(outpath, "output.sorted");
sorter.merge(outfiles, output);
// import the evaluations
LongWritable key = new LongWritable();
DoubleWritable value = new DoubleWritable();
Reader reader = new Reader(fs, output, conf);
try {
while (reader.next(key, value)) {
evaluations.add(value.get());
}
} finally {
reader.close();
}
}
}