org.apache.mahout.math.hadoop

Class MatrixColumnMeansJob.MatrixColumnMeansReducer

java.lang.Object

org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.NullWritable,VectorWritable,org.apache.hadoop.io.IntWritable,VectorWritable>

org.apache.mahout.math.hadoop.MatrixColumnMeansJob.MatrixColumnMeansReducer

Enclosing class:

MatrixColumnMeansJob

public static class MatrixColumnMeansJob.MatrixColumnMeansReducer
extends org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.NullWritable,VectorWritable,org.apache.hadoop.io.IntWritable,VectorWritable>

The reducer adds the partial column-wise sums from each of the mappers to compute the total column-wise sum. The total sum is then divided by the total count of vectors to determine the column-wise mean.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Reducer

org.apache.hadoop.mapreduce.Reducer.Context

Constructor Summary

Constructors

Constructor and Description
MatrixColumnMeansReducer()

Method Summary

Modifier and Type	Method and Description
void	reduce(org.apache.hadoop.io.NullWritable n, Iterable<VectorWritable> vectors, org.apache.hadoop.mapreduce.Reducer.Context context)
void	setup(org.apache.hadoop.mapreduce.Reducer.Context context)

Methods inherited from class org.apache.hadoop.mapreduce.Reducer

cleanup, run

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MatrixColumnMeansReducer

public MatrixColumnMeansReducer()

Method Detail

setup

public void setup(org.apache.hadoop.mapreduce.Reducer.Context context)

Overrides:

setup in class org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.NullWritable,VectorWritable,org.apache.hadoop.io.IntWritable,VectorWritable>

reduce

public void reduce(org.apache.hadoop.io.NullWritable n,
                   Iterable<VectorWritable> vectors,
                   org.apache.hadoop.mapreduce.Reducer.Context context)
            throws IOException,
                   InterruptedException

Overrides:

reduce in class org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.NullWritable,VectorWritable,org.apache.hadoop.io.IntWritable,VectorWritable>

Throws:

IOException

InterruptedException