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

java.lang.Object
  extended by org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.NullWritable,VectorWritable,org.apache.hadoop.io.IntWritable,VectorWritable>
      extended by 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
MatrixColumnMeansJob.MatrixColumnMeansReducer()
           
 
Method Summary
 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

MatrixColumnMeansJob.MatrixColumnMeansReducer

public MatrixColumnMeansJob.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


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