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| <html> |
| <h2>Combine - Combine PerKey</h2> |
| <p>After creating a keyed PCollection (for example, by using a GroupByKey transform), a common |
| pattern is to combine the collection of values associated with each key into a single, merged value. |
| This pattern of a GroupByKey followed by merging the collection of values is equivalent to |
| Combine PerKey transform. The combine function you supply to Combine PerKey must be an associative |
| reduction function or a subclass of CombineFn.</p> |
| <p>In this task, we are going to implement the sum of scores per player using |
| <a href="https://beam.apache.org/releases/pydoc/2.11.0/apache_beam.transforms.core.html#apache_beam.transforms.core.CombinePerKey"> |
| CombinePerKey</a>. |
| </p> |
| <br> |
| <br> |
| <div class='hint'>Use <a href="https://beam.apache.org/releases/pydoc/2.11.0/apache_beam.transforms.core.html#apache_beam.transforms.core.CombinePerKey">CombinePerKey(CombineFn)</a>.</div> |
| <div class='hint'>Extend the <a href="https://beam.apache.org/releases/pydoc/2.11.0/apache_beam.transforms.core.html#apache_beam.transforms.core.CombineFn">CombineFn</a> |
| class that counts the sum of the number.</div> |
| </html> |
