/**
* 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.fpm.pfpgrowth;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.common.Pair;
/**
* takes each group of dependent transactions and\ compacts it in a
* TransactionTree structure
*/
public class ParallelFPGrowthCombiner extends Reducer<LongWritable,TransactionTree,LongWritable,TransactionTree> {
@Override
protected void reduce(LongWritable key, Iterable<TransactionTree> values, Context context)
throws IOException, InterruptedException {
TransactionTree cTree = new TransactionTree();
for (TransactionTree tr : values) {
for (Pair<List<Integer>,Long> p : tr) {
cTree.addPattern(p.getFirst(), p.getSecond());
}
}
context.write(key, cTree.getCompressedTree());
}
}