org.apache.mahout.cf.taste.hadoop.item
Class ToUserVectorsReducer
java.lang.Object
org.apache.hadoop.mapreduce.Reducer<VarLongWritable,VarLongWritable,VarLongWritable,VectorWritable>
org.apache.mahout.cf.taste.hadoop.item.ToUserVectorsReducer
public final class ToUserVectorsReducer
- extends org.apache.hadoop.mapreduce.Reducer<VarLongWritable,VarLongWritable,VarLongWritable,VectorWritable>
Input
Takes user IDs as VarLongWritable
mapped to all associated item IDs and preference values, as
EntityPrefWritable
s.
Output
The same user ID mapped to a RandomAccessSparseVector
representation of the same item IDs and
preference values. Item IDs are used as vector indexes; they are hashed into ints to work as indexes with
TasteHadoopUtils.idToIndex(long)
. The mapping is remembered for later with a combination of
ItemIDIndexMapper
and ItemIDIndexReducer
.
Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Reducer |
org.apache.hadoop.mapreduce.Reducer.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 |
MIN_PREFERENCES_PER_USER
public static final String MIN_PREFERENCES_PER_USER
ToUserVectorsReducer
public ToUserVectorsReducer()
setup
protected void setup(org.apache.hadoop.mapreduce.Reducer.Context ctx)
throws IOException,
InterruptedException
- Overrides:
setup
in class org.apache.hadoop.mapreduce.Reducer<VarLongWritable,VarLongWritable,VarLongWritable,VectorWritable>
- Throws:
IOException
InterruptedException
reduce
protected void reduce(VarLongWritable userID,
Iterable<VarLongWritable> itemPrefs,
org.apache.hadoop.mapreduce.Reducer.Context context)
throws IOException,
InterruptedException
- Overrides:
reduce
in class org.apache.hadoop.mapreduce.Reducer<VarLongWritable,VarLongWritable,VarLongWritable,VectorWritable>
- Throws:
IOException
InterruptedException
Copyright © 2008–2014 The Apache Software Foundation. All rights reserved.