---

title: “Sample”

Sample

{{< localstorage language language-py >}}

{{< button-pydoc path=“apache_beam.transforms.combiners” class=“Sample” >}}

Transforms for taking samples of the elements in a collection, or samples of the values associated with each key in a collection of key-value pairs.

Examples

In the following example, we create a pipeline with a PCollection. Then, we get a random sample of elements in different ways.

Example 1: Sample elements from a PCollection

We use Sample.FixedSizeGlobally() to get a fixed-size random sample of elements from the entire PCollection.

{{< highlight py >}} {{< code_sample “sdks/python/apache_beam/examples/snippets/transforms/aggregation/sample.py” sample_fixed_size_globally >}} {{< /highlight >}}

{{< paragraph class=“notebook-skip” >}} Output: {{< /paragraph >}}

{{< highlight class=“notebook-skip” >}} {{< code_sample “sdks/python/apache_beam/examples/snippets/transforms/aggregation/sample_test.py” sample >}} {{< /highlight >}}

{{< buttons-code-snippet py=“sdks/python/apache_beam/examples/snippets/transforms/aggregation/sample.py” >}}

Example 2: Sample elements for each key

We use Sample.FixedSizePerKey() to get fixed-size random samples for each unique key in a PCollection of key-values.

{{< highlight py >}} {{< code_sample “sdks/python/apache_beam/examples/snippets/transforms/aggregation/sample.py” sample_fixed_size_per_key >}} {{< /highlight >}}

{{< paragraph class=“notebook-skip” >}} Output: {{< /paragraph >}}

{{< highlight class=“notebook-skip” >}} {{< code_sample “sdks/python/apache_beam/examples/snippets/transforms/aggregation/sample_test.py” samples_per_key >}} {{< /highlight >}}

{{< buttons-code-snippet py=“sdks/python/apache_beam/examples/snippets/transforms/aggregation/sample.py” >}}

Related transforms

• Top finds the largest or smallest element.

{{< button-pydoc path=“apache_beam.transforms.combiners” class=“Sample” >}}