Get median of array

Question

I have an array that looks like this:

let arr = [1,2,3,4,5,6,7,8,9]

I know you can get min and max by:

let min = arr.min()
let max = arr.max()

But how do you get the median?

Answer 1

To get the median you can use the following:

let median = arr.sorted(by: <)[arr.count / 2]

In your case it will return 5.

As @Nirav pointed out [1,2,3,4,5,6,7,8] will return 5 but should return 4.5.

Use this instead:

func calculateMedian(array: [Int]) -> Float {
    let sorted = array.sorted()
    if sorted.count % 2 == 0 {
        return Float((sorted[(sorted.count / 2)] + sorted[(sorted.count / 2) - 1])) / 2
    } else {
        return Float(sorted[(sorted.count - 1) / 2])
    }
}

Usage:

let array = [1,2,3,4,5,6,7,8]
let m2 = calculateMedian(array: array) // 4.5