比较Double Swift 4的两个数组

Question

Have two arrays of Doubles, I want to compare them and create a new array with result of the difference, but not sure how to create a loop for that. Please advise.

Example of the arrays here:

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

Answer 1

Zip the arrays to get an array of tuples, and then just use map to calculate difference for each pair:

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)