Swift 3 - 数组映射.根据关系在数组中添加占位符值 [英] Swift 3 - Array mapping. Add placeholder values in array based on relationship

问题描述

我的第一个数组是:

arr1 = [1, 2, 3, 4, 5]

我的第二个数组是:

arr2 = [2, 3, 4]

我的第三个数组是:

arr3 = ["2a", "3a", "4a"]

arr2 和 arr3 通过索引值相关，即 arr2[0] 与 arr3[0] 相关，[1] 和 [2] 也是如此.

arr2 and arr3 are related by index values, i.e., arr2[0] relates to arr3[0], same for [1] and [2].

我已经能够将 arr2 与 arr1 进行比较并添加占位符值，因此我的占位符数组是

I have been able to compare arr2 against arr1 and add placeholder values so my placeholder array for them is

arr1to2 = ["No match", 2, 3, 4, "No Match"]

现在我需要将 arr3 与 arr2 与 arr1(或者 arr1to2)进行比较，所以我的输出应该是

Now I need to compare arr3 against arr2 to arr1 (alternatively arr1to2), so my output should be

array_final = ["No match", 2a, 3a, 4a, "No match"]

我还需要在 array_final 和 arr1to2 的索引值之间保持关系.[1] 涉及 [1]、[2] 到 [2]、[3] 到 [3].

I need to have the relationship maintained between index values of array_final and arr1to2 as well. [1] relates [1], [2] to [2], [3] to [3].

推荐答案

你可以这样做:

let arr1 = [1, 2, 3, 4, 5]
let arr2 = [2, 3, 4]
let arr3 = ["2a", "3a", "4a"]

// first lets join arr2 and arr3 to a dictionary
var dict: [Int: String] = [:]
zip(arr2, arr3).forEach({ (pair) in
    dict[pair.0] = pair.1
})

// and then just map each value in arr1 according to the dictionary, or provide a "No match" default
let result = arr1.map { (value) -> String in
    return dict[value] ?? "No match"
}

print(result)

这篇关于Swift 3 - 数组映射.根据关系在数组中添加占位符值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！