将集合流平面映射到其元素流

Question

我有一系列事件流，想将其平面映射到事件流中。

flatMap函数的语法有问题

val stream = DataStream[Seq[Event]]

stream.flatMap(???)

任何帮助将不胜感激

Answer 1

I suggest you look at the examples that come with Flink, such as this wordcount application:

val counts: DataStream[(String, Int)] = text
  // split up the lines in pairs (2-tuples) containing: (word,1)
  .flatMap(_.toLowerCase.split("\\W+"))
  .filter(_.nonEmpty)
  .map((_, 1))
  // group by the tuple field "0" and sum up tuple field "1"
  .keyBy(0)
  .sum(1)

The documentation also has helpful code snippets in scala (and java).