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title: “Mean”

Mean

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Transforms for computing the arithmetic mean of the elements in a collection, or the mean 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 the element with the average value in different ways.

Example 1: Mean of element in a PCollection

We use Mean.Globally() to get the average of the elements from the entire PCollection.

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

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

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

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

Example 2: Mean of elements for each key

We use Mean.PerKey() to get the average of the elements for each unique key in a PCollection of key-values.

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

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

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

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

Related transforms

• CombineGlobally
• CombinePerKey
• Max
• Min
• Sum

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