How to write method to calculate average in Swift-playground

Question

In swift I'm trying to write a method to calculate the average. Using the method below if i type average(5,10,15) I get infinity displayed in the swift-playforund

func average(numbers: Int...) -> Double {
    var sum = 0
    var count = 0
    for number in numbers {
        sum += number
    }
    var  ave : Double = Double(sum) / Double(count)
    return ave
}

Answer 1

import Accelerate

let avg = vDSP.mean(array)

This will be at least 50x faster than all other solutions posted so far.

Answer 2

It's so much easier with just a straightforward call to reduce:

let array = [1.0,2.0,3.0]
var average = array.reduce(0.0) {
    return $0 + $1/Double(array.count)
}
// average = 2.0

Answer 3

You can use the count property of the array:

func average(numbers: Int...) -> Double {
    var sum = 0
    for number in numbers {
        sum += number
    }
    var  ave : Double = Double(sum) / Double(numbers.count)
    return ave
}

Answer 4

While others have already pointed out the missing count variable, it is worth noting that you can do the average even more elegantly by using closures as follows:

func averagec(numbers:Int...) -> Double {
    return Double(numbers.reduce(0,combine:+))/Double(numbers.count)
}

Edited for Swift 4:-

func averagec(numbers:Int...) -> Double {
    return Double(numbers.reduce(0,+))/Double(numbers.count)
}

Answer 5

Just write count = count +1 in your for loop.

Such like,,,

.
.
.
for number in numbers 
{
  sum += number
  count = count +1
}
.
.

And now function by

var avg:Double = average(5,10,15)
println(avg)

Answer 6

You forget to increment count in the inner loop.

Answer 7

You're getting infinity because count is always 0 - it's never incremented. So the ave variable is always going to be equal to some number over 0, which is a divide by zero error.

Either use countElements(numbers) or increment count on each iteration through the loop.

Answer 8

Here's what I did:

func getAverage(nums: Double...) ->Double
{
    var temp = 0.0
    for num in nums
    {
        temp+=num
    }
    let div = Double(nums.count)
    var average = temp/div
    return average
}
getAverage(21,34.5,28,79)

Note that I'm accepting Doubles as input, not just Ints. I'm being a little verbose at the end, but I was trying for readable code. I probably could have just returned:

 return temp/Double(nums.count)

at the end and saved a few lines of code.

Answer 9

Swift 3, functional style

func average(numbers: Int...) -> Double {
    assert(numbers.count > 0)
    return numbers.reduce(0, {$0 + Double($1)})/Double(numbers.count)
}