Rendere la mia funzione calcolare la media dell'array Swift

Question

Voglio che la mia funzione calcoli la media della mia matrice di tipo Double. L'array è chiamato "voti". Per ora, ho 10 numeri.

Quando chiamo lo average function per ottenere la media dei voti dell'array, non funziona.

Ecco il mio codice:

var votes = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] 

func average(nums: Double...) -> Double { 
    var total = 0.0 

    for vote in votes { 
    total += vote 
    } 
    let votesTotal = Double(votes.count) 
    var average = total/votesTotal 
    return average 
    } 

average[votes] 

Come chiamare la media qui per ottenere la media?

Answer 1

si dovrebbe utilizzare il metodo di ridurre() per sommare l'array come segue:

Xcode 9 • Swift 4

extension Array where Element: Numeric { 
    /// Returns the total sum of all elements in the array 
    var total: Element { return reduce(0, +) } 
} 

extension Array where Element: BinaryInteger { 
    /// Returns the average of all elements in the array 
    var average: Double { 
     return isEmpty ? 0 : Double(Int(total))/Double(count) 
    } 
} 

extension Array where Element: FloatingPoint { 
    /// Returns the average of all elements in the array 
    var average: Element { 
     return isEmpty ? 0 : total/Element(count) 
    } 
} 

---

let votes = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] 
let votesTotal = votes.total  // 55 
let votesAverage = votes.average // "5.5" 

---

Xcode 8.3.2 • Swift 3,1

extension Array where Element == Int { 
    /// Returns the sum of all elements in the array 
    var total: Element { 
     return reduce(0, +) 
    } 
    /// Returns the average of all elements in the array 
    var average: Double { 
     return isEmpty ? 0 : Double(reduce(0, +))/Double(count) 
    } 
} 

---

extension Array where Element: FloatingPoint { 
    /// Returns the sum of all elements in the array 
    var total: Element { 
     return reduce(0, +) 
    } 
    /// Returns the average of all elements in the array 
    var average: Element { 
     return isEmpty ? 0 : total/Element(count) 
    } 
} 

Answer 2

Hai alcuni errori nel codice:

//You have to set the array-type to Double. Because otherwise Swift thinks that you need an Int-array 
var votes:[Double] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] 

func average(nums: [Double]) -> Double { 

    var total = 0.0 
    //use the parameter-array instead of the global variable votes 
    for vote in nums{ 

     total += Double(vote) 

    } 

    let votesTotal = Double(nums.count) 
    var average = total/votesTotal 
    return average 
} 

var theAverage = average(votes)