| # |
| # 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. |
| # |
| |
| """Simple tests to showcase combiners. |
| |
| The tests are meant to be "copy/paste" code snippets for the topic they address |
| (combiners in this case). Most examples use neither sources nor sinks. |
| The input data is generated simply with a Create transform and the output is |
| checked directly on the last PCollection produced. |
| """ |
| |
| from __future__ import absolute_import |
| |
| import logging |
| import unittest |
| |
| import apache_beam as beam |
| from apache_beam.testing.test_pipeline import TestPipeline |
| from apache_beam.testing.util import assert_that |
| from apache_beam.testing.util import equal_to |
| |
| |
| class CombinersTest(unittest.TestCase): |
| """Tests showcasing Dataflow combiners.""" |
| |
| SAMPLE_DATA = [ |
| ('a', 1), ('b', 10), ('a', 2), ('a', 3), ('b', 20), ('c', 100)] |
| |
| def test_combine_per_key_with_callable(self): |
| """CombinePerKey using a standard callable reducing iterables. |
| |
| A common case for Dataflow combiners is to sum (or max or min) over the |
| values of each key. Such standard functions can be used directly as combiner |
| functions. In fact, any function "reducing" an iterable to a single value |
| can be used. |
| """ |
| result = ( |
| TestPipeline() |
| | beam.Create(CombinersTest.SAMPLE_DATA) |
| | beam.CombinePerKey(sum)) |
| |
| assert_that(result, equal_to([('a', 6), ('b', 30), ('c', 100)])) |
| result.pipeline.run() |
| |
| def test_combine_per_key_with_custom_callable(self): |
| """CombinePerKey using a custom function reducing iterables.""" |
| def multiply(values): |
| result = 1 |
| for v in values: |
| result *= v |
| return result |
| |
| result = ( |
| TestPipeline() |
| | beam.Create(CombinersTest.SAMPLE_DATA) |
| | beam.CombinePerKey(multiply)) |
| |
| assert_that(result, equal_to([('a', 6), ('b', 200), ('c', 100)])) |
| result.pipeline.run() |
| |
| |
| if __name__ == '__main__': |
| logging.getLogger().setLevel(logging.INFO) |
| unittest.main() |