LookupPostings.java Source code

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Here is the source code for LookupPostings.java

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/*
 * 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.
 */

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;

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.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.MapFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

import edu.umd.cloud9.io.array.ArrayListWritable;
import edu.umd.cloud9.io.pair.PairOfInts;
import edu.umd.cloud9.io.pair.PairOfWritables;
import edu.umd.cloud9.util.fd.Int2IntFrequencyDistribution;
import edu.umd.cloud9.util.fd.Int2IntFrequencyDistributionEntry;

public class LookupPostings extends Configured implements Tool {
    private static final String INDEX = "index";
    private static final String COLLECTION = "collection";

    private LookupPostings() {
    }

    /**
     * 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(INDEX));
        options.addOption(
                OptionBuilder.withArgName("path").hasArg().withDescription("output path").create(COLLECTION));

        CommandLine cmdline = null;
        CommandLineParser parser = new GnuParser();

        try {
            cmdline = parser.parse(options, args);
        } catch (ParseException exp) {
            System.err.println("Error parsing command line: " + exp.getMessage());
            System.exit(-1);
        }

        if (!cmdline.hasOption(INDEX) || !cmdline.hasOption(COLLECTION)) {
            System.out.println("args: " + Arrays.toString(args));
            HelpFormatter formatter = new HelpFormatter();
            formatter.setWidth(120);
            formatter.printHelp(LookupPostings.class.getName(), options);
            ToolRunner.printGenericCommandUsage(System.out);
            System.exit(-1);
        }

        String indexPath = cmdline.getOptionValue(INDEX);
        String collectionPath = cmdline.getOptionValue(COLLECTION);

        if (collectionPath.endsWith(".gz")) {
            System.out.println("gzipped collection is not seekable: use compressed version!");
            System.exit(-1);
        }

        Configuration config = new Configuration();
        FileSystem fs = FileSystem.get(config);
        MapFile.Reader reader = new MapFile.Reader(new Path(indexPath + "/part-r-00000"), config);

        FSDataInputStream collection = fs.open(new Path(collectionPath));
        BufferedReader d = new BufferedReader(new InputStreamReader(collection));

        Text key = new Text();
        PairOfWritables<IntWritable, ArrayListWritable<PairOfInts>> value = new PairOfWritables<IntWritable, ArrayListWritable<PairOfInts>>();

        System.out.println("Looking up postings for the term \"starcross'd\"");
        key.set("starcross'd");

        reader.get(key, value);

        ArrayListWritable<PairOfInts> postings = value.getRightElement();
        for (PairOfInts pair : postings) {
            System.out.println(pair);
            collection.seek(pair.getLeftElement());
            System.out.println(d.readLine());
        }

        key.set("gold");
        reader.get(key, value);
        System.out.println("Complete postings list for 'gold': " + value);

        Int2IntFrequencyDistribution goldHist = new Int2IntFrequencyDistributionEntry();
        postings = value.getRightElement();
        for (PairOfInts pair : postings) {
            goldHist.increment(pair.getRightElement());
        }

        System.out.println("histogram of tf values for gold");
        for (PairOfInts pair : goldHist) {
            System.out.println(pair.getLeftElement() + "\t" + pair.getRightElement());
        }

        key.set("silver");
        reader.get(key, value);
        System.out.println("Complete postings list for 'silver': " + value);

        Int2IntFrequencyDistribution silverHist = new Int2IntFrequencyDistributionEntry();
        postings = value.getRightElement();
        for (PairOfInts pair : postings) {
            silverHist.increment(pair.getRightElement());
        }

        System.out.println("histogram of tf values for silver");
        for (PairOfInts pair : silverHist) {
            System.out.println(pair.getLeftElement() + "\t" + pair.getRightElement());
        }

        key.set("bronze");
        Writable w = reader.get(key, value);

        if (w == null) {
            System.out.println("the term bronze does not appear in the collection");
        }

        collection.close();
        reader.close();

        return 0;
    }

    /**
     * Dispatches command-line arguments to the tool via the {@code ToolRunner}.
     */
    public static void main(String[] args) throws Exception {
        ToolRunner.run(new LookupPostings(), args);
    }
}