| # 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. |
| |
| # beam-playground: |
| # name: With-keys |
| # description: WithKeys example. |
| # multifile: false |
| # context_line: 48 |
| # categories: |
| # - Quickstart |
| # complexity: BASIC |
| # tags: |
| # - hellobeam |
| |
| |
| import apache_beam as beam |
| |
| # Output PCollection |
| class Output(beam.PTransform): |
| class _OutputFn(beam.DoFn): |
| def __init__(self, prefix=''): |
| super().__init__() |
| self.prefix = prefix |
| |
| def process(self, element): |
| print(self.prefix+str(element)) |
| |
| def __init__(self, label=None,prefix=''): |
| super().__init__(label) |
| self.prefix = prefix |
| |
| def expand(self, input): |
| input | beam.ParDo(self._OutputFn(self.prefix)) |
| |
| with beam.Pipeline() as p: |
| (p | beam.Create(['apple', 'banana', 'cherry', 'durian', 'guava', 'melon']) |
| # The WithKeys return Map which key will be first letter word and value word |
| | beam.WithKeys(lambda word: word[0:1]) |
| | Output(prefix='PCollection with-keys value: ')) |
