Java tutorial
/* * Cloud9: A Hadoop toolkit for working with big data * * Licensed 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 edu.umd.gorden2; import java.io.IOException; import java.util.*; import java.io.*; import java.net.URI; import org.apache.commons.io.FileUtils; import org.apache.commons.io.IOUtils; import org.apache.commons.cli.CommandLine; import org.apache.commons.cli.CommandLineParser; import org.apache.commons.cli.GnuParser; import org.apache.commons.cli.HelpFormatter; import org.apache.commons.cli.OptionBuilder; import org.apache.commons.cli.Options; import org.apache.commons.cli.ParseException; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.DoubleWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.Partitioner; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.apache.log4j.Logger; import tl.lin.data.pair.PairOfStrings; /** * <p> * Implementation of the "pairs" algorithm for computing co-occurrence matrices from a large text * collection. This algorithm is described in Chapter 3 of "Data-Intensive Text Processing with * MapReduce" by Lin & Dyer, as well as the following paper: * </p> * * <blockquote>Jimmy Lin. <b>Scalable Language Processing Algorithms for the Masses: A Case Study in * Computing Word Co-occurrence Matrices with MapReduce.</b> <i>Proceedings of the 2008 Conference * on Empirical Methods in Natural Language Processing (EMNLP 2008)</i>, pages 419-428.</blockquote> * * @author Jimmy Lin */ public class PairsPMI extends Configured implements Tool { private static final Logger LOG = Logger.getLogger(PairsPMI.class); private static class MyMapper extends Mapper<LongWritable, Text, PairOfStrings, DoubleWritable> { private static final PairOfStrings PAIR = new PairOfStrings(); private static final DoubleWritable ONE = new DoubleWritable(1.0d); @Override public void map(LongWritable key, Text line, Context context) throws IOException, InterruptedException { String text = line.toString(); String[] s = text.trim().split("\\s+"); // eliminate the dup words Set<String> ss = new HashSet<String>(Arrays.asList(s)); String[] terms = ss.toArray(new String[ss.size()]); for (int i = 0; i < terms.length; i++) { String term = terms[i]; // skip empty tokens if (term.length() == 0) continue; for (int j = 0; j < terms.length; j++) { if (i != j) { PAIR.set(term, terms[j]); context.write(PAIR, ONE); } } } } } // WordCount Mapper private static class MyMapper2 extends Mapper<LongWritable, Text, Text, IntWritable> { // Reuse objects to save overhead of object creation. private final static IntWritable ONE = new IntWritable(1); private final static Text WORD = new Text(); @Override public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { String line = ((Text) value).toString(); String[] s = line.trim().split("\\s+"); // eliminate the dup words Set<String> ss = new HashSet<String>(Arrays.asList(s)); String[] terms = ss.toArray(new String[ss.size()]); // number of Lines WORD.set("*"); context.write(WORD, ONE); for (int i = 0; i < terms.length; i++) { String term = terms[i]; if (term.length() == 0) continue; WORD.set(term); context.write(WORD, ONE); } } } // WordCount Reducer private static class MyReducer2 extends Reducer<Text, IntWritable, Text, IntWritable> { // Reuse objects. private final static IntWritable SUM = new IntWritable(); @Override public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { // Sum up values. Iterator<IntWritable> iter = values.iterator(); int sum = 0; while (iter.hasNext()) { sum += iter.next().get(); } SUM.set(sum); context.write(key, SUM); } } // Pair Combiner private static class MyCombiner extends Reducer<PairOfStrings, DoubleWritable, PairOfStrings, DoubleWritable> { private final static DoubleWritable SUM = new DoubleWritable(); @Override public void reduce(PairOfStrings key, Iterable<DoubleWritable> values, Context context) throws IOException, InterruptedException { Iterator<DoubleWritable> iter = values.iterator(); double sum = 0.0d; while (iter.hasNext()) { sum += iter.next().get(); } SUM.set(sum); context.write(key, SUM); } } // Pair Reducer private static class MyReducer extends Reducer<PairOfStrings, DoubleWritable, PairOfStrings, DoubleWritable> { private final static DoubleWritable PMI = new DoubleWritable(); HashMap<String, Double> sidemap = new HashMap<String, Double>(); @Override protected void setup(Context context) throws IOException, InterruptedException { if (context.getCacheFiles() != null && context.getCacheFiles().length > 0) { URI mappingFileUri = context.getCacheFiles()[0]; if (mappingFileUri != null) { String side_file = FileUtils.readFileToString(new File("./part-r-00000")); String[] token = side_file.split("\\s+"); for (int i = 0; i <= token.length - 2; i += 2) { sidemap.put(token[i], Double.parseDouble(token[i + 1])); } } else { System.out.println(">>>>>> NO MAPPING FILE"); } } else { System.out.println(">>>>>> NO CACHE FILES AT ALL"); } } @Override public void reduce(PairOfStrings key, Iterable<DoubleWritable> values, Context context) throws IOException, InterruptedException { Iterator<DoubleWritable> iter = values.iterator(); double sum = 0.0d; while (iter.hasNext()) { sum += iter.next().get(); } Double pmix = sidemap.get(key.getLeftElement()); Double pmiy = sidemap.get(key.getRightElement()); Double count = sidemap.get("*"); Double pmixy = sum; if (pmixy >= 10) { Double pmi = pmixy * count / (pmix * pmiy); Double logpmi = Math.log10(pmi); PMI.set(logpmi); context.write(key, PMI); } } } // Currently useless protected static class MyPartitioner extends Partitioner<PairOfStrings, DoubleWritable> { @Override public int getPartition(PairOfStrings key, DoubleWritable value, int numReduceTasks) { return (key.getLeftElement().hashCode() & Integer.MAX_VALUE) % numReduceTasks; } } /** * Creates an instance of this tool. */ public PairsPMI() { } private static final String INPUT = "input"; private static final String OUTPUT = "output"; private static final String NUM_REDUCERS = "numReducers"; /** * Runs this tool. */ @SuppressWarnings({ "static-access" }) public int run(String[] args) throws Exception { Options options = new Options(); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("input path").create(INPUT)); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("output path").create(OUTPUT)); options.addOption(OptionBuilder.withArgName("num").hasArg().withDescription("number of reducers") .create(NUM_REDUCERS)); CommandLine cmdline; CommandLineParser parser = new GnuParser(); try { cmdline = parser.parse(options, args); } catch (ParseException exp) { System.err.println("Error parsing command line: " + exp.getMessage()); return -1; } if (!cmdline.hasOption(INPUT) || !cmdline.hasOption(OUTPUT)) { System.out.println("args: " + Arrays.toString(args)); HelpFormatter formatter = new HelpFormatter(); formatter.setWidth(120); formatter.printHelp(this.getClass().getName(), options); ToolRunner.printGenericCommandUsage(System.out); return -1; } String inputPath = cmdline.getOptionValue(INPUT); String outputPath = cmdline.getOptionValue(OUTPUT); int reduceTasks = cmdline.hasOption(NUM_REDUCERS) ? Integer.parseInt(cmdline.getOptionValue(NUM_REDUCERS)) : 1; LOG.info("Tool: " + PairsPMI.class.getSimpleName()); LOG.info(" - input path: " + inputPath); LOG.info(" - output path: " + outputPath); LOG.info(" - number of reducers: " + reduceTasks); // // Pair job Job job = Job.getInstance(getConf()); job.setJobName(PairsPMI.class.getSimpleName()); job.setJarByClass(PairsPMI.class); // Delete the output directory if it exists already. Path outputDir = new Path(outputPath); FileSystem.get(getConf()).delete(outputDir, true); job.setNumReduceTasks(reduceTasks); FileInputFormat.setInputPaths(job, new Path(inputPath)); FileOutputFormat.setOutputPath(job, new Path(outputPath)); job.setMapOutputKeyClass(PairOfStrings.class); job.setMapOutputValueClass(DoubleWritable.class); job.setOutputKeyClass(PairOfStrings.class); job.setOutputValueClass(DoubleWritable.class); job.setMapperClass(MyMapper.class); job.setCombinerClass(MyCombiner.class); job.setReducerClass(MyReducer.class); //job.setPartitionerClass(MyPartitioner.class); job.addCacheFile(new URI("wc/part-r-00000")); long startTime = System.currentTimeMillis(); // // wordcount job Job job2 = Job.getInstance(getConf()); job2.setJobName("Wordcount"); job2.setJarByClass(PairsPMI.class); String outputPath2 = "wc"; // Delete the output directory if it exists already. Path outputDir2 = new Path(outputPath2); FileSystem.get(getConf()).delete(outputDir2, true); job2.setNumReduceTasks(1); FileInputFormat.setInputPaths(job2, new Path(inputPath)); FileOutputFormat.setOutputPath(job2, new Path(outputPath2)); job2.setMapOutputKeyClass(Text.class); job2.setMapOutputValueClass(IntWritable.class); job2.setOutputKeyClass(Text.class); job2.setOutputValueClass(IntWritable.class); job2.setMapperClass(MyMapper2.class); job2.setCombinerClass(MyReducer2.class); job2.setReducerClass(MyReducer2.class); // add side file to job1 job.addCacheFile(new URI("wc/part-r-00000")); job2.waitForCompletion(true); job.waitForCompletion(true); System.out.println("Job Finished in " + (System.currentTimeMillis() - startTime) / 1000.0 + " seconds"); return 0; } /** * Dispatches command-line arguments to the tool via the {@code ToolRunner}. */ public static void main(String[] args) throws Exception { ToolRunner.run(new PairsPMI(), args); } }