org.ankus.mapreduce.algorithms.statistics.numericstats.NumericStats1MRReducer.java Source code

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Here is the source code for org.ankus.mapreduce.algorithms.statistics.numericstats.NumericStats1MRReducer.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 org.ankus.mapreduce.algorithms.statistics.numericstats;

import java.io.IOException;
import java.util.Iterator;

import org.ankus.util.ArgumentsConstants;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

/**
 * NumericStats1MRReducer
 * @desc reducer class for numeric statistics computation mr job (1-step)
 * @version 0.0.1
 * @date : 2013.08.21
 * @author Moonie
 */
public class NumericStats1MRReducer extends Reducer<IntWritable, Text, NullWritable, Text> {

    private String delimiter;

    @Override
    protected void setup(Context context) throws IOException, InterruptedException {
        delimiter = context.getConfiguration().get(ArgumentsConstants.DELIMITER, "\t");
    }

    @Override
    protected void reduce(IntWritable key, Iterable<Text> values, Context context)
            throws IOException, InterruptedException {
        Iterator<Text> iterator = values.iterator();

        int cnt = 0;
        double sum = 0;
        double avg = 0;
        double avgGeometric = 0;
        double avgHarmonic = 0;
        double variance = 0;
        double stdDeviation = 0;
        double maxData = 0;
        double minData = 0;
        double middleData_Value = 0;
        double harmonicSum = 0;
        double geometricSum = 0;
        double squareSum = 0;
        boolean allPositive = true;

        while (iterator.hasNext()) {
            double value = Double.parseDouble(iterator.next().toString());
            cnt++;

            if (cnt == 1) {
                maxData = value;
                minData = value;
            } else {
                if (maxData < value)
                    maxData = value;
                if (minData > value)
                    minData = value;
            }

            if (value <= 0)
                allPositive = false;
            sum += value;
            if (allPositive) {
                harmonicSum += 1 / value;
                geometricSum += Math.log10(value);
            }
            squareSum += Math.pow(value, 2) / 10000;
        }

        avg = sum / (double) cnt;
        if (allPositive) {
            avgHarmonic = (double) cnt / harmonicSum;
            avgGeometric = Math.pow(10, geometricSum / (double) cnt);
        } else {
            avgHarmonic = 0;
            avgGeometric = 0;
        }

        variance = (squareSum * 10000 / (double) cnt) - Math.pow(avg, 2);
        stdDeviation = Math.sqrt(variance);
        middleData_Value = (maxData + minData) / 2;

        String writeVal = sum + delimiter + avg + delimiter + avgHarmonic + delimiter + avgGeometric + delimiter
                + variance + delimiter + stdDeviation + delimiter + maxData + delimiter + minData + delimiter
                + middleData_Value;
        context.write(NullWritable.get(), new Text(key.toString() + delimiter + writeVal));
    }

    @Override
    protected void cleanup(Context context) throws IOException, InterruptedException {
    }
}