初始化多维数组

Question

只是一个小捷径问题。

let history = 5
var gradeTimeline = [Int](count:history*12, repeatedValue:0)

将初始化一个一维数组。有没有办法对二维数组也这样做？长格式为：

var gradesTimeline = [[Int]]()
for i in 0...10 { gradesTimeline.append(gradeTimeline) }

Answer 1

尝试：

var gradesTimeline = (0..<10).map { _ in [Int](count:12*history, repeatedValue:0) }

但是，由于 Array 的值语义，您还可以：

var gradesTimeline = [[Int]](count:2, repeatedValue:([Int](count:3, repeatedValue:0)))

这导致

gradesTimeline: [[Int]] = 2 values {
  [0] = 3 values {
    [0] = 0
    [1] = 0
    [2] = 0
  }
  [1] = 3 values {
    [0] = 0
    [1] = 0
    [2] = 0
  }
}
 18> gradesTimeline[0][0]=10
 19> gradesTimeline[1][2]=20
 20> gradesTimeline
$R4: [[Int]] = 2 values {
  [0] = 3 values {
    [0] = 10
    [1] = 0
    [2] = 0
  }
  [1] = 3 values {
    [0] = 0
    [1] = 0
    [2] = 20
  }
}

初始化多维数组

Init multi-dimensional array

arrays

initialization

swift