Swift Language Finding the minimum or maximum element of an Array


Example

2.12.2

You can use the minElement() and maxElement() methods to find the minimum or maximum element in a given sequence. For example, with an array of numbers:

let numbers = [2, 6, 1, 25, 13, 7, 9]

let minimumNumber = numbers.minElement() // Optional(1)
let maximumNumber = numbers.maxElement() // Optional(25)
3.0

As of Swift 3, the methods have been renamed to min() and max() respectively:

let minimumNumber = numbers.min() // Optional(1)
let maximumNumber = numbers.max() // Optional(25)

The returned values from these methods are Optional to reflect the fact that the array could be empty – if it is, nil will be returned.

Note: The above methods require the elements to conform to the Comparable protocol.

Finding the minimum or maximum element with a custom ordering

You may also use the above methods with a custom closure, defining whether one element should be ordered before another, allowing you to find the minimum or maximum element in an array where the elements aren't necessarily Comparable.

For example, with an array of vectors:

struct Vector2 {
    let dx : Double
    let dy : Double
    
    var magnitude : Double {return sqrt(dx*dx+dy*dy)}
}

let vectors = [Vector2(dx: 3, dy: 2), Vector2(dx: 1, dy: 1), Vector2(dx: 2, dy: 2)]
2.12.2
// Vector2(dx: 1.0, dy: 1.0)
let lowestMagnitudeVec2 = vectors.minElement { $0.magnitude < $1.magnitude } 

// Vector2(dx: 3.0, dy: 2.0)
let highestMagnitudeVec2 = vectors.maxElement { $0.magnitude < $1.magnitude } 
3.0
let lowestMagnitudeVec2 = vectors.min { $0.magnitude < $1.magnitude }
let highestMagnitudeVec2 = vectors.max { $0.magnitude < $1.magnitude }