.shuffle()和.shuffled()是Swift的一部分
原历史问题:
我如何随机或洗牌在Swift数组中的元素?例如,如果我的数组包含52张扑克牌,我想要洗牌数组以洗牌牌组。
.shuffle()和.shuffled()是Swift的一部分
原历史问题:
我如何随机或洗牌在Swift数组中的元素?例如,如果我的数组包含52张扑克牌,我想要洗牌数组以洗牌牌组。
当前回答
let shuffl = GKRandomSource.sharedRandom().arrayByShufflingObjects(in: arrayObject)
其他回答
let shuffl = GKRandomSource.sharedRandom().arrayByShufflingObjects(in: arrayObject)
在Swift 4.2中,现在有一个可变shuffle和不可变shuffle的方法。你可以在这里阅读更多关于随机生成和数组的东西。
你也可以使用通用交换函数,实现前面提到的Fisher-Yates:
for idx in 0..<arr.count {
let rnd = Int(arc4random_uniform(UInt32(idx)))
if rnd != idx {
swap(&arr[idx], &arr[rnd])
}
}
或者更简洁:
for idx in 0..<steps.count {
swap(&steps[idx], &steps[Int(arc4random_uniform(UInt32(idx)))])
}
简单的例子:
extension Array {
mutating func shuffled() {
for _ in self {
// generate random indexes that will be swapped
var (a, b) = (Int(arc4random_uniform(UInt32(self.count - 1))), Int(arc4random_uniform(UInt32(self.count - 1))))
if a == b { // if the same indexes are generated swap the first and last
a = 0
b = self.count - 1
}
swap(&self[a], &self[b])
}
}
}
var array = [1,2,3,4,5,6,7,8,9,10]
array.shuffled()
print(array) // [9, 8, 3, 5, 7, 6, 4, 2, 1, 10]
工作阵列扩展(突变和非突变)
Swift 4.1 / Xcode 9
上面的答案已弃用,所以我自己创建了自己的扩展,在Swift的最新版本Swift 4.1 (Xcode 9)中洗牌数组:
extension Array {
// Non-mutating shuffle
var shuffled : Array {
let totalCount : Int = self.count
var shuffledArray : Array = []
var count : Int = totalCount
var tempArray : Array = self
for _ in 0..<totalCount {
let randomIndex : Int = Int(arc4random_uniform(UInt32(count)))
let randomElement : Element = tempArray.remove(at: randomIndex)
shuffledArray.append(randomElement)
count -= 1
}
return shuffledArray
}
// Mutating shuffle
mutating func shuffle() {
let totalCount : Int = self.count
var shuffledArray : Array = []
var count : Int = totalCount
var tempArray : Array = self
for _ in 0..<totalCount {
let randomIndex : Int = Int(arc4random_uniform(UInt32(count)))
let randomElement : Element = tempArray.remove(at: randomIndex)
shuffledArray.append(randomElement)
count -= 1
}
self = shuffledArray
}
}
调用非突变Shuffle [Array] -> [Array]:
let array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
print(array.shuffled)
这将以随机顺序打印数组。
调用Shuffle [Array] = [Array]:
var array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
array.shuffle()
// The array has now been mutated and contains all of its initial
// values, but in a randomized shuffled order
print(array)
这将打印数组的当前顺序,该顺序已经被随机打乱。
希望这对每个人都有用,如果你有任何问题,建议或评论,请随时提问!