| /** |
| * 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.hama.graph; |
| |
| import org.apache.hadoop.io.DoubleWritable; |
| |
| /** |
| * A absolute difference aggregator, it collects values before the compute and |
| * after the compute, then calculates the difference and globally accumulates |
| * (sums them up) them. |
| */ |
| public class AbsDiffAggregator extends |
| AbstractAggregator<DoubleWritable> { |
| |
| double absoluteDifference = 0.0d; |
| |
| @Override |
| public void aggregate(DoubleWritable oldValue, DoubleWritable newValue) { |
| // make sure it's nullsafe |
| if (oldValue != null) { |
| absoluteDifference += Math.abs(oldValue.get() - newValue.get()); |
| } |
| } |
| |
| // when a master aggregates he aggregated values, he calls this, so let's just |
| // sum up here. |
| @Override |
| public void aggregate(DoubleWritable value) { |
| absoluteDifference += value.get(); |
| } |
| |
| @Override |
| public DoubleWritable getValue() { |
| return new DoubleWritable(absoluteDifference); |
| } |
| |
| } |