org.ankus.mapreduce.algorithms.statistics.numericstats.NumericStats2MRMergeReducer.java Source code

Introduction

Here is the source code for org.ankus.mapreduce.algorithms.statistics.numericstats.NumericStats2MRMergeReducer.java

Source

/*
 * 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.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

/**
 * NumericStats2MRMergeReducer
 * @desc 2nd reducer class for numeric statistics computation mr job (2-step)
 * @version 0.0.1
 * @date : 2013.08.21
 * @author Moonie
 */
public class NumericStats2MRMergeReducer extends Reducer<Text, Text, NullWritable, Text> {

    private String delimiter;

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

    //   @Override
    protected void reduce(Text key, Iterable<Text> values, Context context)
            throws IOException, InterruptedException {
        int cnt = 0;
        double max = 0;
        double min = 0;
        double sum = 0;
        double harmonic_sum = 0;
        double geometric_sum = 0;
        double square_sum = 0;
        boolean allPositive = true;

        Iterator<Text> iterator = values.iterator();
        while (iterator.hasNext()) {
            String tokens[] = iterator.next().toString().split(delimiter);

            int curCnt = Integer.parseInt(tokens[0]);
            double curMax = Double.parseDouble(tokens[1]);
            double curMin = Double.parseDouble(tokens[2]);
            cnt += curCnt;
            if (cnt == curCnt) {
                max = curMax;
                min = curMin;
            } else {
                if (max < curMax)
                    max = curMax;
                if (min > curMin)
                    min = curMin;
            }

            if (tokens[7].equals("F"))
                allPositive = false;
            sum += Double.parseDouble(tokens[3]);
            if (allPositive) {
                harmonic_sum += Double.parseDouble(tokens[4]);
                geometric_sum += Double.parseDouble(tokens[5]);
            }
            square_sum += Double.parseDouble(tokens[6]);
        }

        double avg = sum / (double) cnt;
        double avg_harmonic = 0;
        double avg_geometric = 0;
        if (allPositive) {
            avg_harmonic = (double) cnt / harmonic_sum;
            avg_geometric = Math.pow(10, geometric_sum / (double) cnt);
        }

        double variance = (square_sum * 10000 / (double) cnt) - Math.pow(avg, 2);
        double stdDeviation = Math.sqrt(variance);
        double middleData_Value = (max + min) / 2;

        String writeVal = sum + delimiter + avg + delimiter + avg_harmonic + delimiter + avg_geometric + delimiter
                + variance + delimiter + stdDeviation + delimiter + max + delimiter + min + delimiter
                + middleData_Value;
        context.write(NullWritable.get(), new Text(key.toString() + delimiter + writeVal));
    }

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