Keeps records when fun(T) == true
Keeps records when fun(T) == true
the filter
a new stream after filter
converts a value[T] to a list of value[R]
converts a value[T] to a list of value[R]
FlatMap function
The description message for this operation
A new stream with type [R]
Group by function (T => Group)
Group by function (T => Group)
For example, we have T type, People(name: String, gender: String, age: Int) groupBy[People](_.gender) will group the people by gender.
You can append other combinators after groupBy
For example,
Stream[People].groupBy(_.gender).flatmap(..).filter.(..).reduce(..)
Group by function
Parallelism level
The description
the grouped stream
Log to task log file
Maps message of type T message of type R
Maps message of type T message of type R
Function
A new stream with type [R]
Merges data from two stream into one
Merges data from two stream into one
the other stream
the merged stream
Connects with a low level Processor(TaskDescription)
Connects with a low level Processor(TaskDescription)
a user defined processor
parallelism level
new stream after processing with type [R]
Reduces operations.
Reduces operations.
reduction function
description message for this operator
a new stream after reduction