[英]Flink WindowFunction Fold
I create a sliding window and hope to recursively pack all the elements enter that window period, This is chunk of the code 我创建了一个滑动窗口,希望递归打包进入该窗口期间的所有元素,这是代码的一部分
.map(x => ((x.pickup.get.latitude, x.pickup.get.longitude), (x.dropoff.get.latitude, x.dropoff.get.longitude)))
.windowAll(SlidingEventTimeWindows.of(Time.minutes(10), Time.minutes(1)))
.fold(List[((Double, Double), (Double, Double))]) {(acc, v) => acc :+ ((v._1._1, v._1._2), (v._2._1, v._2._2))}
I hope to create a List
in which the elements are tuple
, but this does not work. 我希望创建一个其中元素为tuple
的List
,但这不起作用。
I tried this and it works: 我试过了,它有效:
val l2 : List[((Int, Int), (Int, Int))] = List(((1, 1), (2, 2)))
val newl2 = l2 :+ ((3, 3), (4, 4))
How can I do this? 我怎样才能做到这一点? Thanks so much 非常感谢
The first argument of the fold
function needs to be the initial value and not the type. fold
函数的第一个参数必须是初始值,而不是类型。 Changing the last line into: 将最后一行更改为:
.fold(List.empty[((Long, Long), (Long, Long))]) {(acc, v) => acc :+ ((v._1._1, v._1._2), (v._2._1, v._2._2))}
should do the trick. 应该可以。
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