/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.cf.taste.hadoop.item;
import java.io.IOException;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.VarIntWritable;
import org.apache.mahout.math.VarLongWritable;
public final class ItemIDIndexReducer extends
Reducer<VarIntWritable, VarLongWritable, VarIntWritable,VarLongWritable> {
@Override
protected void reduce(VarIntWritable index,
Iterable<VarLongWritable> possibleItemIDs,
Context context) throws IOException, InterruptedException {
long minimumItemID = Long.MAX_VALUE;
for (VarLongWritable varLongWritable : possibleItemIDs) {
long itemID = varLongWritable.get();
if (itemID < minimumItemID) {
minimumItemID = itemID;
}
}
if (minimumItemID != Long.MAX_VALUE) {
context.write(index, new VarLongWritable(minimumItemID));
}
}
}