Question

我是Scala的新手。我有一个元组[Int，String]

((1, "alpha"), (2, "beta"), (3, "gamma"), (4, "zeta"), (5, "omega"))

对于上面的列表，我想打印相应长度为4的所有字符串。

Answer 1

在Scala中打印Tuples字符串的长度

val tuples = List((1, "alpha"), (2, "beta"), (3, "gamma"), (4, "zeta"), (5, "omega"))
println(tuples.map(x => (x._2, x._2.length)))
//List((alpha,5), (beta,4), (gamma,5), (zeta,4), (omega,5))

我想打印相应长度为4的所有字符串

您可以filter先行，然后print作为

val tuples = List((1, "alpha"), (2, "beta"), (3, "gamma"), (4, "zeta"), (5, "omega"))
tuples.filter(_._2.length == 4).foreach(x => println(x._2))

它应该打印

beta
zeta

Answer 2

您可以将Tuple转换为List，然后根据需要进行映射和过滤：

tuple.productIterator.toList
.map{case (a,b) => b.toString}
.filter(_.length==4)

示例：

对于给定的输入：

 val tuple = ((1, "alpha"), (2, "beta"), (3, "gamma"), (4, "zeta"), (5, "omega"))
tuple: ((Int, String), (Int, String), (Int, String), (Int, String), (Int, String)) = ((1,alpha),(2,beta),(3,gamma),(4,zeta),(5,omega))

输出：

List[String] = List(beta, zeta)

Answer 3

假设你有一个元组列表，你需要所有字符串长度等于4的值。

您可以在列表中执行过滤：

val filteredList = list.filter(_._2.length == 4)

然后迭代每个元素以打印它们：

filteredList.foreach(tuple => println(tuple._2))

Answer 4

以下是实现此目的的方法

scala> val x = ((1, "alpha"), (2, "beta"), (3, "gamma"), (4, "zeta"), (5, "omega"))
x: ((Int, String), (Int, String), (Int, String), (Int, String), (Int, String)) = ((1,alpha),(2,beta),(3,gamma),(4,zeta),(5,omega))

scala> val y = x.productIterator.toList.collect{
  case ele : (Int, String) if ele._2.length == 4 => ele._2
}
y: List[String] = List(beta, zeta)

在Scala中打印Tuples字符串的长度

4 个答案: