Function groupBy

groupBy<T, K>(key: string | string[] | ((element: T) => K), keyName?: undefined | string): GroupBy<T, K>
Returns a PTransform that takes a PCollection of elements, and returns a PCollection of elements grouped by a field, multiple fields, an expression that is used as the grouping key.

Various fields may be further aggregated with CombineFns by invoking groupBy(...).combining(...).
Type Parameters
- T
- K
Parameters
- key: string | string[] | ((element: T) => K)
- keyName: undefined | string = undefined
Returns GroupBy<T, K>
- Defined in src/apache_beam/transforms/group_and_combine.ts:125