com.yahoo.semsearch.fastlinking.io.WikipediaDocnoMapping.java Source code

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Here is the source code for com.yahoo.semsearch.fastlinking.io.WikipediaDocnoMapping.java

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/*
 * Cloud9: A MapReduce Library for Hadoop
 *
 * 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 com.yahoo.semsearch.fastlinking.io;

import java.io.IOException;
import java.util.Arrays;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.util.LineReader;
import org.apache.log4j.Logger;

import edu.umd.cloud9.collection.DocnoMapping;

/**
 * https://lintool.github.io/Cloud9/
 * <p>
 * Provides a mapping between Wikipedia internal ids (docids) and sequentially-numbered ints
 * (docnos).
 * </p>
 *
 * <p>
 * The <code>main</code> of this class provides a simple program for accessing docno mappings.
 * Command-line arguments are as follows:
 * </p>
 *
 * <ul>
 * <li>getDocno, getDocid: get docno from docid or, get docid from docno</li>
 * <li>[mappings-file]: the mappings file</li>
 * <li>[docid/docno]: the docid or docno (optional)</li>
 * </ul>
 *
 * @author Jimmy Lin
 */
public class WikipediaDocnoMapping implements DocnoMapping {
    private static final Logger LOG = Logger.getLogger(WikipediaDocnoMapping.class);

    private int[] docids;

    /**
     * Creates a {@code WikipediaDocnoMapping} object
     */
    public WikipediaDocnoMapping() {
    }

    @Override
    public int getDocno(String docid) {
        return Arrays.binarySearch(docids, Integer.parseInt(docid));
    }

    @Override
    public String getDocid(int docno) {
        return String.valueOf(docids[docno]);
    }

    @Override
    public void loadMapping(Path p, FileSystem fs) throws IOException {
        docids = WikipediaDocnoMapping.readDocnoMappingData(p, fs);
    }

    /**
     * Creates a mappings file from the contents of a flat text file containing docid to docno
     * mappings. This method is used by {@link WikipediaDocnoMappingBuilder} internally.
     *
     * @param inputFile flat text file containing docid to docno mappings
     * @param outputFile output mappings file
     * @throws IOException
     */
    static public void writeDocnoMappingData(FileSystem fs, String inputFile, int n, String outputFile)
            throws IOException {
        LOG.info("Writing " + n + " docids to " + outputFile);
        LineReader reader = new LineReader(fs.open(new Path(inputFile)));

        int cnt = 0;
        Text line = new Text();

        FSDataOutputStream out = fs.create(new Path(outputFile), true);
        out.writeInt(n);
        for (int i = 0; i < n; i++) {
            reader.readLine(line);
            String[] arr = line.toString().split("\\t");
            out.writeInt(Integer.parseInt(arr[0]));
            cnt++;
            if (cnt % 100000 == 0) {
                LOG.info(cnt + " articles");
            }
        }
        out.close();
        reader.close();
        LOG.info("Done!");
    }

    /**
     * Reads a mappings file into memory.
     *
     * @param p path to the mappings file
     * @param fs appropriate FileSystem
     * @return an array of docids; the index position of each docid is its docno
     * @throws IOException
     */
    static public int[] readDocnoMappingData(Path p, FileSystem fs) throws IOException {
        FSDataInputStream in = fs.open(p);

        // docnos start at one, so we need an array that's one larger than number of docs.
        int sz = in.readInt() + 1;
        int[] arr = new int[sz];

        for (int i = 1; i < sz; i++) {
            arr[i] = in.readInt();
        }
        in.close();

        arr[0] = 0;

        return arr;
    }

    @Override
    public Builder getBuilder() {
        return new WikipediaDocnoMappingBuilder();
    }

    /**
     * Simple program the provides access to the docno/docid mappings.
     *
     * @param args command-line arguments
     * @throws IOException
     */
    public static void main(String[] args) throws IOException {
        if (args.length < 2) {
            System.out.println("usage: (getDocno|getDocid|printAll) [mapping-file] [docid/docno]");
            System.exit(-1);
        }

        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);

        System.out.println("loading mapping file " + args[1]);
        WikipediaDocnoMapping mapping = new WikipediaDocnoMapping();
        mapping.loadMapping(new Path(args[1]), fs);

        if (args[0].equals("getDocno")) {
            System.out.println("looking up docno for \"" + args[2] + "\"");
            int idx = mapping.getDocno(args[2]);
            if (idx > 0) {
                System.out.println(mapping.getDocno(args[2]));
            } else {
                System.err.print("Invalid docid!");
            }
        } else if (args[0].equals("getDocid")) {
            try {
                System.out.println("looking up docid for " + args[2]);
                System.out.println(mapping.getDocid(Integer.parseInt(args[2])));
            } catch (Exception e) {
                System.err.print("Invalid docno!");
            }
        } else if (args[0].equals("printAll")) {
            for (int docno = 1; docno < mapping.docids.length; docno++) {
                System.out.println(mapping.getDocid(docno) + "\t" + docno);
            }
        } else {
            System.out.println("Invalid command!");
            System.out.println("usage: (getDocno|getDocid) [mapping-file] [docid/docno]");
        }
    }
}