Swift 以特定顺序连接 2 个数组

Question

我在操场上写了以下代码，它运行良好，但看起来有点乱。有没有更简洁的 Swift 编写方式？

我希望字符串如下所示： 1、12、2、12、3、12、4、13、5、13、6、13、7、14、8、14

我不会知道每个数组中有多少个值，数组可能不是偶数，但我会知道每个array2值的3个array1值的关系

let array1 = [1,2,3,4,5,6,7,8]  //sample 1st array
let array2 = [12,13,14]         //sample 2nd array

let relationshipInterval = 3
let remainder = (array1.count % relationshipInterval)
let multiples = (array1.count - remainder)/relationshipInterval
var string = ""
var array1Start = 0
var array1End = relationshipInterval-1
var array2Value = 0

for _ in 1...multiples {
    for array1value in array1[array1Start...array1End] {
    string += "\(array1value), "
    string += String(array2[array2Value])+", "
    }
    array1Start = array1End + 1
    array1End = array1Start + relationshipInterval - 1
    array2Value += 1
}

for array1value in array1[array1Start...array1Start+remainder-1] {
        string += "\(array1value), "
        string += String(array2[array2Value])+", "
}
print (string)  //prints 1, 12, 2, 12, 3, 12, 4, 13, 5, 13, 6, 13, 7, 14, 8, 14

Answer 1

我不确定这是否涵盖了所有用例，但使用 zip、flatMap 和 joined 只需一步！

let array1 = [1,2,3,4,5,6,7,8]
let array2 = [12, 13, 14]

let text = zip(array1, array2.flatMap({ [$0, $0, $0] }))
    .flatMap({ [$0, $1] })
    .map({ String($0) })
    .joined(separator: ", ")

// text -> "1, 12, 2, 12, 3, 12, 4, 13, 5, 13, 6, 13, 7, 14, 8, 14"

这是一个分为四个步骤的单行代码，以便更清楚地了解每个阶段发生的情况：

// 1. create an array with each element in array2 is trippled:
let trippled = array2.flatMap({ item in
    return [item, item, item]
})
// trippled -> [12, 12, 12, 13, 13, 13, 14, 14, 14]

// 2. zip array1 with the trippled array:
let zipped = zip(array1, trippled)
// zipped -> Zip2Sequence(_sequence1: [1, 2, 3, 4, 5, 6, 7, 8], _sequence2: [12, 12, 12, 13, 13, 13, 14, 14, 14])

// 3. flatten the zipped aray
let combined = zipped.flatMap({ leftItem, rightItem in
    return [leftItem, rightItem]
})
// combined -> [1, 12, 2, 12, 3, 12, 4, 13, 5, 13, 6, 13, 7, 14, 8, 14]

// 4. tranform to a string
let text = combined.map({ item in
    return "\(item)"
}).joined(separator: ", ")
// text -> "1, 12, 2, 12, 3, 12, 4, 13, 5, 13, 6, 13, 7, 14, 8, 14"