| /* |
| * 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.beam.learning.katas.coretransforms.combine.combinefn; |
| |
| import java.io.Serializable; |
| import java.util.Objects; |
| import org.apache.beam.learning.katas.util.Log; |
| import org.apache.beam.sdk.Pipeline; |
| import org.apache.beam.sdk.options.PipelineOptions; |
| import org.apache.beam.sdk.options.PipelineOptionsFactory; |
| import org.apache.beam.sdk.transforms.Combine; |
| import org.apache.beam.sdk.transforms.Combine.CombineFn; |
| import org.apache.beam.sdk.transforms.Create; |
| import org.apache.beam.sdk.values.PCollection; |
| |
| public class Task { |
| |
| public static void main(String[] args) { |
| PipelineOptions options = PipelineOptionsFactory.fromArgs(args).create(); |
| Pipeline pipeline = Pipeline.create(options); |
| |
| PCollection<Integer> numbers = pipeline.apply(Create.of(10, 20, 50, 70, 90)); |
| |
| PCollection<Double> output = applyTransform(numbers); |
| |
| output.apply(Log.ofElements()); |
| |
| pipeline.run(); |
| } |
| |
| static PCollection<Double> applyTransform(PCollection<Integer> input) { |
| return input.apply(Combine.globally(new AverageFn())); |
| } |
| |
| static class AverageFn extends CombineFn<Integer, AverageFn.Accum, Double> { |
| |
| class Accum implements Serializable { |
| int sum = 0; |
| int count = 0; |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| if (o == null || getClass() != o.getClass()) { |
| return false; |
| } |
| Accum accum = (Accum) o; |
| return sum == accum.sum && |
| count == accum.count; |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hash(sum, count); |
| } |
| } |
| |
| @Override |
| public Accum createAccumulator() { |
| return new Accum(); |
| } |
| |
| @Override |
| public Accum addInput(Accum accumulator, Integer input) { |
| accumulator.sum += input; |
| accumulator.count++; |
| |
| return accumulator; |
| } |
| |
| @Override |
| public Accum mergeAccumulators(Iterable<Accum> accumulators) { |
| Accum merged = createAccumulator(); |
| |
| for (Accum accumulator : accumulators) { |
| merged.sum += accumulator.sum; |
| merged.count += accumulator.count; |
| } |
| |
| return merged; |
| } |
| |
| @Override |
| public Double extractOutput(Accum accumulator) { |
| return ((double) accumulator.sum) / accumulator.count; |
| } |
| |
| } |
| |
| } |