Java tutorial
/** * 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.cd.tool; import java.io.BufferedWriter; import java.io.IOException; import java.io.OutputStreamWriter; import java.util.Collection; import java.util.List; import java.util.Locale; import java.util.Scanner; import com.google.common.base.Preconditions; import com.google.common.collect.Lists; import com.google.common.io.Closeables; import org.apache.commons.cli2.CommandLine; import org.apache.commons.cli2.Group; import org.apache.commons.cli2.Option; import org.apache.commons.cli2.OptionException; import org.apache.commons.cli2.builder.GroupBuilder; import org.apache.commons.cli2.commandline.Parser; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FSDataInputStream; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.SequenceFile; import org.apache.hadoop.io.Writable; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.input.TextInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat; import org.apache.mahout.common.CommandLineUtil; import org.apache.mahout.common.commandline.DefaultOptionCreator; import org.apache.mahout.common.iterator.sequencefile.SequenceFileValueIterable; import org.apache.mahout.ga.watchmaker.OutputUtils; import org.apache.mahout.ga.watchmaker.cd.FileInfoParser; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Gathers additional information about a given dataset. Takes a descriptor * about the attributes, and generates a description for each one. */ public final class CDInfosTool { private static final Logger log = LoggerFactory.getLogger(CDInfosTool.class); private CDInfosTool() { } /** * Uses Mahout to gather the information about a dataset. * * @param descriptors about the available attributes * @param inpath input path (the dataset) * @param descriptions {@code List<String>} that contains the * generated descriptions for each non ignored attribute */ public static void gatherInfos(Descriptors descriptors, Path inpath, Path output, Collection<String> descriptions) throws IOException, InterruptedException, ClassNotFoundException { Configuration conf = new Configuration(); FileSystem fs = FileSystem.get(inpath.toUri(), conf); Preconditions.checkArgument(fs.exists(inpath) && fs.getFileStatus(inpath).isDir(), "%s is not a directory", inpath); Job job = new Job(conf); configureJob(job, descriptors, inpath, output); job.waitForCompletion(true); importDescriptions(fs, conf, output, descriptions); } /** * Configure the job * * @param descriptors attributes's descriptors * @param inpath input {@code Path} * @param outpath output {@code Path} */ private static void configureJob(Job job, Descriptors descriptors, Path inpath, Path outpath) throws IOException { FileInputFormat.setInputPaths(job, inpath); FileOutputFormat.setOutputPath(job, outpath); job.setJarByClass(CDInfosTool.class); job.setOutputKeyClass(LongWritable.class); job.setOutputValueClass(Text.class); job.setMapperClass(ToolMapper.class); job.setCombinerClass(ToolCombiner.class); job.setReducerClass(ToolReducer.class); job.setInputFormatClass(TextInputFormat.class); job.setOutputFormatClass(SequenceFileOutputFormat.class); // store the stringified descriptors job.getConfiguration().set(ToolMapper.ATTRIBUTES, new String(descriptors.getChars())); } /** * Reads back the descriptions. * * @param fs file system * @param conf job configuration * @param outpath output {@code Path} * @param descriptions List of attribute's descriptions */ private static void importDescriptions(FileSystem fs, Configuration conf, Path outpath, Collection<String> descriptions) throws IOException { SequenceFile.Sorter sorter = new SequenceFile.Sorter(fs, LongWritable.class, Text.class, conf); // merge and sort the outputs Path[] outfiles = OutputUtils.listOutputFiles(fs, outpath); Path output = new Path(outpath, "output.sorted"); sorter.merge(outfiles, output); // import the descriptions for (Writable value : new SequenceFileValueIterable<Writable>(output, true, conf)) { descriptions.add(value.toString()); } } /** * Load the dataset's attributes descriptors from an .info file * * @param inpath dataset path */ private static Descriptors loadDescriptors(FileSystem fs, Path inpath) throws IOException { // TODO should become part of FileInfoParser Path infpath = FileInfoParser.getInfoFile(fs, inpath); FSDataInputStream input = fs.open(infpath); Scanner reader = new Scanner(input); List<Character> descriptors = Lists.newArrayList(); while (reader.hasNextLine()) { String c = reader.nextLine(); descriptors.add(c.toUpperCase(Locale.ENGLISH).charAt(0)); } if (descriptors.isEmpty()) { throw new IllegalArgumentException("Infos file is empty"); } char[] desc = new char[descriptors.size()]; for (int index = 0; index < descriptors.size(); index++) { desc[index] = descriptors.get(index); } return new Descriptors(desc); } private static void storeDescriptions(FileSystem fs, Path inpath, Descriptors descriptors, List<String> descriptions) throws IOException { // TODO should become part of FileInfoParser Path infpath = FileInfoParser.getInfoFile(fs, inpath); BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(fs.create(infpath))); try { int aindex = 0; for (int index = 0; index < descriptors.size(); index++) { if (descriptors.isLabel(index)) { writer.write(FileInfoParser.LABEL_TOKEN + ", "); writer.write(descriptions.get(aindex++)); } else if (descriptors.isNumerical(index)) { writer.write(FileInfoParser.NUMERICAL_TOKEN + ", "); writer.write(descriptions.get(aindex++)); } else if (descriptors.isNominal(index)) { writer.write(FileInfoParser.NOMINAL_TOKEN + ", "); writer.write(descriptions.get(aindex++)); } else { writer.write(FileInfoParser.IGNORED_TOKEN); } writer.newLine(); } } finally { Closeables.closeQuietly(writer); } } public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException { GroupBuilder gbuilder = new GroupBuilder(); Option inputOpt = DefaultOptionCreator.inputOption().create(); Option helpOpt = DefaultOptionCreator.helpOption(); Group group = gbuilder.withName("Options").withOption(inputOpt).withOption(helpOpt).create(); Parser parser = new Parser(); parser.setGroup(group); try { CommandLine cmdLine = parser.parse(args); if (cmdLine.hasOption(helpOpt)) { CommandLineUtil.printHelp(group); return; } Path input = new Path(cmdLine.getValue(inputOpt).toString()); Path output = new Path("output"); // TODO surely this should be configurable? FileSystem fs = FileSystem.get(input.toUri(), new Configuration()); log.info("Loading Descriptors..."); Descriptors descriptors = loadDescriptors(fs, input); log.info("Gathering informations..."); List<String> descriptions = Lists.newArrayList(); gatherInfos(descriptors, input, output, descriptions); log.info("Storing Descriptions..."); storeDescriptions(fs, input, descriptors, descriptions); } catch (OptionException e) { log.error("Error while parsing options", e); CommandLineUtil.printHelp(group); } } }