scala 系列 ---- scan，scanLeft，scanRight的使用详解用法及代码示例-蒲公英云

scala 系列 ---- scan，scanLeft，scanRight的使用详解用法及代码示例

悠悠 2023-01-08 12:29 213阅读 0赞

scan[B >: A, That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[List[A], B, That]): That

由一个初始值开始，从左向右，进行积累的op操作

scanLeft,scanRight

scanLeft: scanLeft[B, That](z: B)(op: (B, A) ⇒ B)(implicit bf: CanBuildFrom[List[A], B, That]): That

scanRight: scanRight[B, That](z: B)(op: (A, B) ⇒ B)(implicit bf: CanBuildFrom[List[A], B, That]): That

scanLeft: 从左向右进行scan函数的操作，scanRight：从右向左进行scan函数的操作

var scanVector = (1 to 10).scan(0)(_ + _)
    println(scanVector.getClass)
    println(scanVector)
    println("-------------------------------------------------")
    var slVector = (1 to 10).scanLeft(0)(_ + _)
    println(slVector.getClass)
    println(slVector)
    println("-------------------------------------------------")
    var srVector = (1 to 10).scanRight(0)(_ + _)
    println(srVector.getClass)
    println(srVector)
输出：
class scala.collection.immutable.Vector
Vector(0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55)
-------------------------------------------------
class scala.collection.immutable.Vector
Vector(0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55)
-------------------------------------------------
class scala.collection.immutable.Vector
Vector(55, 54, 52, 49, 45, 40, 34, 27, 19, 10, 0)