com.jhkt.playgroundArena.hadoop.tasks.jobs.reducer.AverageMultipleOutputReducer.java Source code

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Here is the source code for com.jhkt.playgroundArena.hadoop.tasks.jobs.reducer.AverageMultipleOutputReducer.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 com.jhkt.playgroundArena.hadoop.tasks.jobs.reducer;

import java.io.IOException;

import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.output.MultipleOutputs;

import com.jhkt.playgroundArena.hadoop.tasks.jobs.writable.AverageWritable;

/**
 * @author Ji Hoon Kim
 */
public final class AverageMultipleOutputReducer extends Reducer<Text, AverageWritable, Text, DoubleWritable> {

    private MultipleOutputs<Text, DoubleWritable> _mOutputs;
    private DoubleWritable _dWriter = new DoubleWritable();

    protected void setup(Reducer<Text, AverageWritable, Text, DoubleWritable>.Context context)
            throws IOException, InterruptedException {
        _mOutputs = new MultipleOutputs<>(context);
    };

    protected void reduce(Text key, Iterable<AverageWritable> values,
            Reducer<Text, AverageWritable, Text, DoubleWritable>.Context context)
            throws IOException, InterruptedException {
        double sum = 0;
        int count = 0;

        for (AverageWritable value : values) {
            sum += value.getSum();
            count += value.getCount();
        }
        double avg = sum / count;
        _dWriter.set(avg);

        String namedOutput = avg > 1000 ? "greaterThan1000" : "lessThan1000";
        _mOutputs.write(namedOutput, key, _dWriter);
    };

}