具有二进制运算的泛型函数 [英] Generic function with binary operations

问题描述

我具有以下函数来返回数组的规范化版本，该数组的元素可以是Int，Double，Float.

I have the following function to return the normalized version of an array whose elements could be Int, Double, Float.

我收到下面第5行指示的错误.我以为数字协议可以解决二进制操作，但我猜不是.我在做什么错了?

I'm getting the error indicated on line 5 below. I thought the Numeric protocol would address the binary operation but I guess not. What am I doing wrong?

func normalizeArray<T: Comparable & Numeric>(a: [T]) -> [T] {
    let min: T = a.min()!
    let max: T = a.max()!

    let n = a.map({ ($0 - min) / (max - min) }) <--- Binary operator '/' cannot be applied to two 'T' operands

    return n
}

谢谢

推荐答案

Numeric 协议需要加，减和乘运算符， 但不是除法运算符.

The Numeric protocol requires addition, subtraction and multiplication operators, but not a division operator.

我不知道需要整数和浮点类型都符合的除法运算符的协议，因此您必须 实现两个重载函数:

I am not aware of a protocol which requires a division operator to which both integer and floating point types conform, therefore you have to implement two overloaded functions:

func normalizeArray<T: FloatingPoint>(a: [T]) -> [T] { ... }

func normalizeArray<T: BinaryInteger>(a: [T]) -> [T] { ... }

请注意，如果使用空白调用，您的实现将崩溃 阵列，我会建议

Note that your implementation will crash if called with an empty array, I'll suggest

func normalizeArray<T: BinaryInteger>(a: [T]) -> [T] {
    guard let min = a.min(), let max = a.max() else {
        return []
    }
    return a.map({ ($0 - min) / (max - min) })
}

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