scala - 用上一个元素折叠

Question

给定val as: Seq[Int] = ...
很多时候，我需要对两个连续的元素进行操作，例如

顺便说一句，我不喜欢

for (i <- 1 until as.size) {
  // do something with as(i) and as(i - 1)
}

或另一个

as.tail.foldLeft((0, as.head)) { (acc, e) =>
  // do something with acc._2 and e 
  // and try to not forget returning (_, e) 
}

如何为这种情况编写更好的代码？

Answer 1

您可以使用自己的zip对序列as进行tail:

for ((prev, curr) <- as zip as.tail) {
  // do something with `prev` and `curr`
}

或者您可以使用 sliding:

for (window <- as.sliding(2)) {
  val prev = window(0)
  val curr = window(1)
  // do something with `prev` and `curr`
}