assignment1.WordCount.WordCountInMap.java Source code

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Here is the source code for assignment1.WordCount.WordCountInMap.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.
 */
package assignment1.WordCount;

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;

import java.io.IOException;
import java.util.HashMap;
import java.util.StringTokenizer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/* InMap Combiner - Example Word Count
Could be an issue if the input cannot be contained in the memory.
 */
public class WordCountInMap {

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

        private final static Pattern nw1 = Pattern.compile("[^'a-zA-Z]");
        private final static Pattern nw2 = Pattern.compile("(^'+|'+$)");
        private final static IntWritable count = new IntWritable();
        private Text word = new Text();

        private HashMap<String, Integer> counts;

        public void setup(Context context) {
            counts = new HashMap<>();
        }

        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {

            StringTokenizer itr = new StringTokenizer(value.toString());
            while (itr.hasMoreTokens()) {
                Matcher mm1 = nw1.matcher(itr.nextToken());
                Matcher mm2 = nw2.matcher(mm1.replaceAll(""));
                String ww = mm2.replaceAll("").toLowerCase();

                if (!ww.equals("")) {
                    if (!counts.containsKey(ww)) {
                        counts.put(ww, 0);
                    }
                    int xx = counts.get(ww);
                    counts.put(ww, xx + 1);
                }
            }

        }

        public void cleanup(Context context) throws InterruptedException, IOException {
            for (String ww : counts.keySet()) {
                word.set(ww);
                count.set(counts.get(ww));
                context.write(word, count);
            }
        }
    }

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

        public void reduce(Text key, Iterable<IntWritable> values, Context context)
                throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable val : values) {
                sum += val.get();
            }
            result.set(sum);
            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: hadoop jar This.jar <in> [<in>...] <out>");
            System.exit(2);
        }
        Job job = new Job(conf, "word count");
        job.setJarByClass(assignment1.WordCount.WordCountInMap.class);
        job.setMapperClass(TokenizerMapper.class);
        //job.setCombinerClass(IntSumReducer.class);
        job.setReducerClass(IntSumReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        for (int i = 0; i < otherArgs.length - 1; ++i) {
            FileInputFormat.addInputPath(job, new Path(otherArgs[i]));
        }
        FileOutputFormat.setOutputPath(job, new Path(otherArgs[otherArgs.length - 1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}