| # 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. |
| |
| import apache_beam as beam |
| |
| from log_elements import LogElements |
| |
| |
| class AverageFn(beam.CombineFn): |
| |
| def create_accumulator(self): |
| return 0.0, 0 |
| |
| def add_input(self, accumulator, element): |
| (sum, count) = accumulator |
| return sum + element, count + 1 |
| |
| def merge_accumulators(self, accumulators): |
| sums, counts = zip(*accumulators) |
| return sum(sums), sum(counts) |
| |
| def extract_output(self, accumulator): |
| (sum, count) = accumulator |
| return sum / count if count else float('NaN') |
| |
| |
| with beam.Pipeline() as p: |
| |
| (p | beam.Create([10, 20, 50, 70, 90]) |
| | beam.CombineGlobally(AverageFn()) |
| | LogElements()) |
| |
