LinkedGraph.java Source code

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Here is the source code for LinkedGraph.java

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/**
 * 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.
 */

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
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.GenericOptionsParser;

public class LinkedGraph {

    public static class TokenizerMapper extends Mapper<Object, Text, Text, Text> {

        private final static IntWritable one = new IntWritable(1);
        //
        private Text word1 = new Text();
        private Text word2 = new Text();

        // text can accept string 
        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            StringTokenizer itr = new StringTokenizer(value.toString());

            //
            int count = 0;
            String[] words = new String[2];
            while (itr.hasMoreTokens()) {

                String tmp = itr.nextToken();

                words[count] = tmp;

                if (count == 1) {
                    word1.set(words[1]);
                    word2.set(words[0]);
                    context.write(word1, word2);
                    //
                    // word2.set(word[0]);
                    // context.write(word2, words[0]);
                }

                count = (count + 1) % 2;

                // word.set(itr.nextToken());
                // context.write(word, one);
            }
        }
    }

    public static class IntSumReducer extends Reducer<Text, Text, Text, Text> {
        private IntWritable result = new IntWritable();

        //accept a string sth = new Text()

        private Text res = new Text();

        public void reduce(Text key, Iterable<Text> values, Context context)
                throws IOException, InterruptedException {
            // int sum = 0;
            StringBuilder sb = new StringBuilder();
            String str = null;

            for (Text val : values) {
                sb.append(val + " ");
            }

            if (sb.length() > 0) {
                str = "(" + sb.toString().trim() + ")";
            }

            res.set(str);
            context.write(key, res);

            // for (IntWritable val : values) {
            //   sum += val.get();
            // }
            // result.set(sum);
            // //sth.set(res) 
            // context.write(key, result);
        }
    }

    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
        if (otherArgs.length != 2) {
            System.err.println("Usage: wordcount <in> <out>");
            System.exit(2);
        }
        Job job = new Job(conf, "Graph");
        job.setJarByClass(LinkedGraph.class);
        job.setMapperClass(TokenizerMapper.class);
        job.setCombinerClass(IntSumReducer.class);
        job.setReducerClass(IntSumReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);
        FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
        FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}