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layout: section title: “Keys” permalink: /documentation/transforms/python/elementwise/keys/ section_menu: section-menu/documentation.html

Keys

{% include button-pydoc.md path=“apache_beam.transforms.util” class=“Keys” %}

Takes a collection of key-value pairs and returns the key of each element.

Example

In the following example, we create a pipeline with a PCollection of key-value pairs. Then, we apply Keys to extract the keys and discard the values.

{% github_sample /apache/beam/blob/master/sdks/python/apache_beam/examples/snippets/transforms/elementwise/keys.py tag:keys %}```

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Output `PCollection` after `Keys`:

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{% github_sample /apache/beam/blob/master/sdks/python/apache_beam/examples/snippets/transforms/elementwise/keys_test.py tag:icons %}```

{% include buttons-code-snippet.md py=“sdks/python/apache_beam/examples/snippets/transforms/elementwise/keys.py” notebook=“examples/notebooks/documentation/transforms/python/elementwise/keys” %}

Related transforms

• [KvSwap]({{ site.baseurl }}/documentation/transforms/python/elementwise/kvswap) swaps the key and value of each element.
• [Values]({{ site.baseurl }}/documentation/transforms/python/elementwise/values) for extracting the value of each element.

{% include button-pydoc.md path=“apache_beam.transforms.util” class=“Keys” %}