| # |
| # 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. |
| # |
| |
| """A workflow using custom JSON-based coders for text sources and sinks. |
| |
| The input file contains a JSON string on each line describing a match |
| record using the following schema: |
| |
| {'guest': [TEAM_NAME, GOALS], 'host': [TEAM_NAME, GOALS]} |
| |
| The output file will contain the computed points for each team with one team |
| per line in the following format: |
| |
| [TEAM_NAME, POINTS] |
| """ |
| |
| from __future__ import absolute_import |
| |
| import argparse |
| import json |
| import logging |
| from builtins import object |
| |
| import apache_beam as beam |
| from apache_beam.io import ReadFromText |
| from apache_beam.io import WriteToText |
| from apache_beam.options.pipeline_options import PipelineOptions |
| from apache_beam.options.pipeline_options import SetupOptions |
| |
| |
| class JsonCoder(object): |
| """A JSON coder interpreting each line as a JSON string.""" |
| |
| def encode(self, x): |
| return json.dumps(x) |
| |
| def decode(self, x): |
| return json.loads(x) |
| |
| |
| def compute_points(record): |
| """Compute points based on the record containing the match result. |
| |
| The function assigns 3 points for a win, 1 point for a draw, and 0 points for |
| a loss (see http://en.wikipedia.org/wiki/Three_points_for_a_win). |
| """ |
| host_name, host_goals = record['host'] |
| guest_name, guest_goals = record['guest'] |
| if host_goals == guest_goals: |
| yield host_name, 1 |
| yield guest_name, 1 |
| elif host_goals > guest_goals: |
| yield host_name, 3 |
| yield guest_name, 0 |
| else: |
| yield host_name, 0 |
| yield guest_name, 3 |
| |
| |
| def run(argv=None): |
| """Runs the workflow computing total points from a collection of matches.""" |
| |
| parser = argparse.ArgumentParser() |
| parser.add_argument('--input', |
| required=True, |
| help='Input file to process.') |
| parser.add_argument('--output', |
| required=True, |
| help='Output file to write results to.') |
| known_args, pipeline_args = parser.parse_known_args(argv) |
| # We use the save_main_session option because one or more DoFn's in this |
| # workflow rely on global context (e.g., a module imported at module level). |
| pipeline_options = PipelineOptions(pipeline_args) |
| pipeline_options.view_as(SetupOptions).save_main_session = True |
| |
| with beam.Pipeline(options=pipeline_options) as p: |
| (p # pylint: disable=expression-not-assigned |
| | 'read' >> ReadFromText(known_args.input, coder=JsonCoder()) |
| | 'points' >> beam.FlatMap(compute_points) |
| | beam.CombinePerKey(sum) |
| | 'write' >> WriteToText(known_args.output, coder=JsonCoder())) |
| |
| |
| if __name__ == '__main__': |
| logging.getLogger().setLevel(logging.INFO) |
| run() |