Swift3循环字典增加值

Question

我是编程新手，我只是在 Playground 上玩耍，我试图在字典中循环进行一些计算并将它们添加到新字典中，但是，我只能添加一个字典值。我不知道为什么。能再告诉我并指出要点吗？

    var name:String?

var popDict: [String: Array<Double>]?
var FinalDict: [String: Array<Double>]?
var mean: Double?
var elementSideArr: Array<Double>?

var nameArray = ["Olivia": [1,2,2,2,1,2,1,0.0001,0,1,2], "Amber": [52,52,65,66,57,63,62,0.0001,0,0,0]]

var doubleArr = [Double]()

for (key, value) in nameArray{

  let thisValue = value
  let arrayS = thisValue.prefix(7)
  let slice = arrayS[0...6]
  let popSideArr = Array(slice)
  let average: Double = (popSideArr as NSArray).value(forKeyPath: "@avg.self") as! Double

      mean = average
  let thatValue = value
  let arraySS = thatValue.suffix(3)
  let sslice = arraySS[8...10]
   elementSideArr = Array(sslice)


  elementSideArr?.insert(average, at: 0)


  let dict = ["\(key)":  elementSideArr!]

  for (key,value) in dict{

    popDict = dict

  }
}
print(popDict!)

["Olivia": [1.5714285714285714, 0.0, 1.0, 2.0]]//这是唯一的输出，但应该是 2 项。

Answer 1

问题出在你的内部for循环中，你正在将整个新字典初始化为popDict，而且如果你的字典只有单个键和值对，你也不需要for循环。

替换代码行:

let dict = ["\(key)":  elementSideArr!]
for (key,value) in dict{
    popDict = dict
}

与:

popDict["\(key)"] = elementSideArr!

注意:无需将 swift 数组转换为 NSArray 来计算平均值，您只需使用 reduce 即可获取总计，然后除以总计与数组计数。

let array = popSideArr as? [Int] ?? []
let res = Double(array.reduce(0, +)) / Double(popSideArr.count)