Swift - `范围最小 - 最大范围内的数字

Question

如何缩放数字以适应指定范围？例如，如果我有:

Input_min = 10.1;
Input_max = 750.0;

Range_min = 0.0;
Range_max = 350.0;

example Input_n = 503.9;

如何使用 swift 使任何数字在最小值和最大值范围内缩放？

Answer 1

编辑/更新:Xcode 11.5 • Swift 5.2

extension FloatingPoint {
    func converting(from input: ClosedRange<Self>, to output: ClosedRange<Self>) -> Self {
        let x = (output.upperBound - output.lowerBound) * (self - input.lowerBound)
        let y = (input.upperBound - input.lowerBound)
        return x / y + output.lowerBound
    }
}

---

extension BinaryInteger {
    func converting(from input: ClosedRange<Self>, to output: ClosedRange<Self>) -> Self {
        let x = (output.upperBound - output.lowerBound) * (self - input.lowerBound)
        let y = (input.upperBound - input.lowerBound)
        return x / y + output.lowerBound
    }
}

---

let integer = 380
let result = integer.converting(from: 10...750, to: 100...350) // 225

let double = 750.0
let result = double.converting(from: 10.1...750.0, to: 0...350) // 350