如何从元组数组创建字典？

Question

假设我有可以识别的对象数组，我想从中创建字典。我可以很容易地从我的数组中获取元组：

let tuples = myArray.map { return ($0.id, $0) }

但是我看不到字典的初始化器来获取元组数组。我错过了什么吗？我是否为此功能创建了字典扩展（事实上它并不难，但我认为默认情况下会提供）或者有更简单的方法吗？

有扩展代码

extension Dictionary
{
    public init (_ arrayOfTuples : Array<(Key, Value)>)
    {
        self.init(minimumCapacity: arrayOfTuples.count)

        for tuple in arrayOfTuples
        {
            self[tuple.0] = tuple.1
        }
    }
}

Answer 1

快捷键4

如果您的元组是（Hashable，String），则可以使用：

let array = [("key1", "value1"), ("key2", "value2"), ("key3", "value3")]
let dictionary = array.reduce(into: [:]) { $0[$1.0] = $1.1 }
print(dictionary) // ["key1": "value1", "key2": "value2", "key3": "value3"]

Answer 2

根据您的目的，您可以：

let tuples = [(0, "0"), (1, "1"), (1, "2")]
var dictionary = [Int: String]()

选项1：替换现有密钥

tuples.forEach {
    dictionary[$0.0] = $0.1
}    
print(dictionary) //prints [0: "0", 1: "2"]

选项2：不允许重复密钥

enum Errors: Error {
    case DuplicatedKeyError
}

do {
    try tuples.forEach {
        guard dictionary.updateValue($0.1, forKey:$0.0) == nil else { throw Errors.DuplicatedKeyError }
    }
    print(dictionary)
} catch {
    print("Error") // prints Error
}

Answer 3

通用方法：

/**
 * Converts tuples to dict
 */
func dict<K,V>(_ tuples:[(K,V)])->[K:V]{
    var dict:[K:V] = [K:V]()
    tuples.forEach {dict[$0.0] = $0.1}
    return dict
}

功能编程更新：

func dict<K,V>(tuples:[(K,V)])->[K:V]{
    return tuples.reduce([:]) {
       var dict:[K:V] = $0
       dict[$1.0] = $1.1   
       return dict
    }
}

Answer 4

使用扩展程序改进了@GitSync答案。

extension Array {
    func toDictionary<K,V>() -> [K:V] where Iterator.Element == (K,V) {
        return self.reduce([:]) {
            var dict:[K:V] = $0
            dict[$1.0] = $1.1
            return dict
        }
    }
}

Answer 5

雨燕4

您可以使用Dictionary的本机init函数：

plugins {
    id 'java'
}

sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

    dependencies {
        compile 'com.google.cloud:google-cloud-monitoring:1.48.0'
        // exception with the dependency below
        compile 'com.google.cloud.dataflow:google-cloud-dataflow-java-sdk-all:2.5.0'

    }

Answer 6

更新为@Stefan答案。

extension Array {

    func toDictionary<K, V>() -> [K: V] where Iterator.Element == (K, V) {
        return Dictionary(uniqueKeysWithValues: self)
    }
}