比较Double Swift 4的两个数组

Question

有两个Doubles数组，我想将它们进行比较并创建一个具有差异结果的新数组，但不确定如何为此创建循环。 请指教。

数组示例：

 var freshRates = [1.6,1.7,2.0]
 var oldRates = [1.5,1.4,1.9]
 var difference: [Double] = []

Answer 1

压缩数组以获得元组数组，然后仅使用map计算每对的差：

var freshRates = [1.6,1.7,2.0]
var oldRates = [1.5,1.4,1.9]
var difference: [Double] = zip(freshRates, oldRates).map({ $0.0 - $0.1 })

Answer 2

var freshRates = [1.6,1.7,2.0]
var oldRates = [1.5,1.4,1.9]
var difference: [Double] = []

for (val1,val2) in zip(freshRates, oldRates){
    difference.append(val2 - val1)
}

debugPrint(difference)