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| <html> |
| <h2>Combine - CombineFn</h2> |
| <p>Combine is a Beam transform for combining collections of elements or values in your data. |
| When you apply a Combine transform, you must provide the function that contains the logic for |
| combining the elements or values. The combining function should be commutative and associative, |
| as the function is not necessarily invoked exactly once on all values with a given key. Because |
| the input data (including the value collection) may be distributed across multiple workers, the |
| combining function might be called multiple times to perform partial combining on subsets of |
| the value collection.</p> |
| <p>Complex combination operations might require you to create a subclass of CombineFn that has an |
| accumulation type distinct from the input/output type. You should use CombineFn if the combine |
| function requires a more sophisticated accumulator, must perform additional pre- or |
| post-processing, might change the output type, or takes the key into account.</p> |
| <p>In this task, we are going to implement the average of numbers using |
| <a href="https://beam.apache.org/releases/pydoc/2.11.0/apache_beam.transforms.core.html#apache_beam.transforms.core.CombineFn"> |
| Combine.CombineFn</a>. |
| </p> |
| <br> |
| <br> |
| <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 average of the number. |
| </div> |
| </html> |
