.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
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]
其他回答
工作! !生物体是要洗牌的数组。
extension Array
{
/** Randomizes the order of an array's elements. */
mutating func shuffle()
{
for _ in 0..<10
{
sort { (_,_) in arc4random() < arc4random() }
}
}
}
var organisms = [
"ant", "bacteria", "cougar",
"dog", "elephant", "firefly",
"goat", "hedgehog", "iguana"]
print("Original: \(organisms)")
organisms.shuffle()
print("Shuffled: \(organisms)")
SWIFT 4
func createShuffledSequenceOfNumbers(max:UInt)->[UInt] {
var array:[UInt]! = []
var myArray:[UInt]! = []
for i in 1...max {
myArray.append(i)
}
for i in 1...max {
array.append(i)
}
var tempArray:[Int]! = []
for index in 0...(myArray.count - 1) {
var isNotFinded:Bool = true
while(isNotFinded){
let randomNumber = arc4random_uniform(UInt32(myArray.count))
let randomIndex = Int(randomNumber)
if(!tempArray.contains(randomIndex)){
tempArray.append(randomIndex)
array[randomIndex] = myArray[index]
isNotFinded = false
}
}
}
return array
}
这是一些在playground上运行的代码。你不需要在实际的Xcode项目中导入Darwin。
import darwin
var a = [1,2,3,4,5,6,7]
func shuffle<ItemType>(item1: ItemType, item2: ItemType) -> Bool {
return drand48() > 0.5
}
sort(a, shuffle)
println(a)
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]