快学SCALA--数组相关操作

Posted 2020-09-06 paulingzhou

val a = Array(2, 4, 5, 6)

val result = for(elem <- a) yield 2 * elem　　　　//result = (4,8, 10, 12)

val result1 = for(elem <- a if elem % 2 == 0) yield 2 * elem　　　　//result1 = (4,8,12)

val result2 = a.filter(_ % 2 == 0).map(2 * _ )　　　　//result = (4,8,12)

val result3 = a.filter(_ % 2 == 0) map {2 * _ }　　　　//result = (4, 8, 12)

 

举例：删除一个数组内除了第一个负数外的其他负数

  def removeNeg(a: Array[Int]) = {
    var first = true
    val indexes = for(i <- 0 until a.length if first || a(i) > 0) yield {
      if(a(i) < 0) first = false;i
    }
    for(j <- 0 until indexes.length) a(j) = a(indexes(j))
    val b = a.toBuffer
    b.trimEnd(a.length - indexes.length)
    b.toArray
  }

 

求和

Array/ArrayBuffer(...).sum

最大最小

Array/ArrayBuffer(...).max/min

排序

不修改原始版本

val b = Array/ArrayBuffer(...)

val bSorted = b.sorted

val bDescending = b.sortedWith(_>_)

在原有数组基础上排序（不能对数组缓冲操作）

val a = Array()

scala.util.Sorting.quichSort(a)

显示数组或数组缓冲的内容

a.mkString(" and ")　　//"1 and 2 and 3"

a.mkString("<", ",", ">")　　//"<1,2,3>"