| Transform | Description |
|---|
| Filter | Given a predicate, filter out all elements that don't satisfy the predicate. |
| FlatMapElements | Applies a function that returns a collection to every element in the input and
outputs all resulting elements. |
| Keys | Extracts the key from each element in a collection of key-value pairs. |
| KvSwap | Swaps the key and value of each element in a collection of key-value pairs. |
| MapElements | Applies a function to every element in the input and outputs the result. |
| ParDo | The most-general mechanism for applying a user-defined DoFn to every element
in the input collection. |
| Partition | Routes each input element to a specific output collection based on some partition
function. |
| Regex | Filters input string elements based on a regex. May also transform them based on the matching groups. |
| Reify | Transforms for converting between explicit and implicit form of various Beam values. |
| ToString | Transforms every element in an input collection to a string. |
| WithKeys | Produces a collection containing each element from the input collection converted to a key-value pair, with a key selected by applying a function to the input element. |
| WithTimestamps | Applies a function to determine a timestamp to each element in the output collection,
and updates the implicit timestamp associated with each input. Note that it is only safe to adjust timestamps forwards. |
| Values | Extracts the value from each element in a collection of key-value pairs. |
| Transform | Description |
|---|
| ApproximateQuantiles | Uses an approximation algorithm to estimate the data distribution within each aggregation using a specified number of quantiles. |
| ApproximateUnique | Uses an approximation algorithm to estimate the number of unique elements within each aggregation. |
| CoGroupByKey | Similar to GroupByKey, but groups values associated with each key into a batch of a given size |
| Combine | Transforms to combine elements according to a provided CombineFn. |
| CombineWithContext | An extended version of Combine which allows accessing side-inputs and other context. |
| Count | Counts the number of elements within each aggregation. |
| Distinct | Produces a collection containing distinct elements from the input collection. |
| GroupByKey | Takes a keyed collection of elements and produces a collection where each element
consists of a key and all values associated with that key. |
| GroupIntoBatches | Batches values associated with keys into Iterable batches of some size. Each batch contains elements associated with a specific key. |
| HllCount | Estimates the number of distinct elements and creates re-aggregatable sketches using the HyperLogLog++ algorithm. |
| Latest | Selects the latest element within each aggregation according to the implicit timestamp. |
| Max | Outputs the maximum element within each aggregation. |
| Mean | Computes the average within each aggregation. |
| Min | Outputs the minimum element within each aggregation. |
| Sample | Randomly select some number of elements from each aggregation. |
| Sum | Compute the sum of elements in each aggregation. |
| Top | Compute the largest element(s) in each aggregation. |