たかがシャッフル、されどシャッフル 〜"permute-with-all" order biasの検証〜

var anArray = ["阿部","伊東","佐藤","鈴木","田中","中村","藤井","松井","村田","吉田"]
for i in 0 ..< anArray.count{
            let r = Int(arc4random_uniform(UInt32(anArray.count)))
            anArray.swapAt(i, r)
        }

        //要素数 = n,試行回数 = repeatCount (自由に変更して下さい)
        let n = 5
        let repeatCount = 100000
        //twoDimArray[要素番号][試行回数何回目か] = 移動先の番号
        var twoDimArray = [[Int]]()
        let originalArray = Array<Int>(0 ..< n)
        for _ in 0 ..< n{
            twoDimArray.append([])
        }
        for _ in 0 ..< repeatCount{
            var anArray = originalArray
            for i in 0 ..< n{
                let r = Int(arc4random_uniform(UInt32(n)))
                anArray.swapAt(i, r)
                }
            for i in 0 ..< n{
                twoDimArray[i].append(anArray.index(of: i)!)
                }
        }
        for i in 0 ..< n{
            var postShuffleCite = [Int](repeating: 0, count: n)
            for j in 0 ..< repeatCount{
                postShuffleCite[twoDimArray[i][j]] += 1
            }
            for k in 0 ..< n{
                let probability = Double(postShuffleCite[k]) / Double(repeatCount) * 100.0
                print("\(i)が\(k)番目に移動する確率は、\(probability)%")
            }
            print("\n")
        }

let r = Int(arc4random_uniform(UInt32(n)))

let r = Int(arc4random_uniform(UInt32(n - i))) + i

extension Array{
    mutating func shuffle(){
        let n = self.count
        for i in 0 ..< n{
            let r = Int(arc4random_uniform(UInt32(n - i))) + i
            self.swapAt(i, r)
        }
    }
}

for i in 0 ..< n{
                let r = Int(arc4random_uniform(UInt32(n)))
                anArray.swapAt(i, r)
                }

anArray.shuffle()