/*
* Source code for Listing 6.2
*
*/
package mia.recommender.ch06;
import java.io.IOException;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.VarLongWritable;
import org.apache.mahout.math.VectorWritable;
import org.apache.mahout.math.Vector;
public class WikipediaToUserVectorReducer
extends
Reducer<VarLongWritable, VarLongWritable, VarLongWritable, VectorWritable> {
public void reduce(VarLongWritable userID,
Iterable<VarLongWritable> itemPrefs, Context context)
throws IOException, InterruptedException {
Vector userVector = new RandomAccessSparseVector(Integer.MAX_VALUE, 100);
for (VarLongWritable itemPref : itemPrefs) {
userVector.set((int) itemPref.get(), 1.0f);
}
context.write(userID, new VectorWritable(userVector));
}
}