org.apache.mahout.cf.taste.hadoop.item

Class ItemFilterAsVectorAndPrefsReducer

java.lang.Object

org.apache.hadoop.mapreduce.Reducer<VarLongWritable,VarLongWritable,VarIntWritable,VectorAndPrefsWritable>

org.apache.mahout.cf.taste.hadoop.item.ItemFilterAsVectorAndPrefsReducer

public class ItemFilterAsVectorAndPrefsReducer
extends org.apache.hadoop.mapreduce.Reducer<VarLongWritable,VarLongWritable,VarIntWritable,VectorAndPrefsWritable>

we use a neat little trick to explicitly filter items for some users: we inject a NaN summand into the preference estimation for those items, which makes AggregateAndRecommendReducer automatically exclude them

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
ItemFilterAsVectorAndPrefsReducer()

Method Summary

Modifier and Type	Method and Description
protected void	reduce(VarLongWritable itemID, Iterable<VarLongWritable> values, org.apache.hadoop.mapreduce.Reducer.Context ctx)

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

cleanup, run, setup

Methods inherited from class java.lang.Object

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

Constructor Detail

ItemFilterAsVectorAndPrefsReducer

public ItemFilterAsVectorAndPrefsReducer()

Method Detail

reduce

protected void reduce(VarLongWritable itemID,
                      Iterable<VarLongWritable> values,
                      org.apache.hadoop.mapreduce.Reducer.Context ctx)
               throws IOException,
                      InterruptedException

Overrides:

reduce in class org.apache.hadoop.mapreduce.Reducer<VarLongWritable,VarLongWritable,VarIntWritable,VectorAndPrefsWritable>

Throws:

IOException

InterruptedException