xcode 在 Swift 中使用“Map”创建两个数组的超集
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Using "Map" in Swift To Create Superset of Two Arrays
提问by doc92606
Let's say I have two arrays:
假设我有两个数组：
let letterArray = ["a", "b", "c", "d", "e"...]
let numberArray = [1, 2, 3, 4, 5, 6, 7...]
I want to combine the two arrays so that I would get an output of
我想组合这两个数组，以便获得输出
["a1", "b2", "c3", "d4", "e5"]
How would I go about doing that?
我该怎么做呢？
回答by Alexander - Reinstate Monica
You can use zip(_:_:)before map:
您可以zip(_:_:)在地图之前使用：
let a = ["a", "b", "c", "d", "e"]
let b = [1, 2, 3, 4, 5]
let result = zip(a, b).map { let result = letterArray.enumerate().map { let result = letterArray.enumerate().flatMap {
guard numberArray.count > func zip<Sequence1, Sequence2>(_ sequence1: Sequence1, _ sequence2: Sequence2) -> Zip2Sequence<Sequence1, Sequence2> where Sequence1 : Sequence, Sequence2 : Sequence
.index else { return .None }
return let letterArray = ["a", "b", "c", "d", "e"]
let numberArray = [1, 2, 3, 4, 5, 6, 7]
let zipSequence = zip(letterArray, numberArray)
let finalArray = zipSequence.map({ (tuple: (letter: String, number: Int)) -> String in
return tuple.letter + String(tuple.number)
})
print(finalArray) // prints ["a1", "b2", "c3", "d4", "e5"]
.element + String(numberArray[let letterArray = ["a", "b", "c", "d", "e"]
let numberArray = [1, 2, 3, 4, 5, 6, 7]
let finalArray = zip(letterArray, numberArray).map { let letterArray = ["a", "b", "c", "d", "e"]
let numberArray = [1, 2, 3, 4, 5, 6, 7]
let zipSequence = zip(letterArray, numberArray)
let finalArray = zipSequence.reduce([]) { (partialResult: [String], tuple: (letter: String, number: Int)) -> [String] in
return partialResult + [tuple.letter + String(tuple.number)]
}
print(finalArray) // prints ["a1", "b2", "c3", "d4", "e5"]
.0 + String(extension Array where Element == String {
func mergeLettersWithNumbers(from numberArray: [Int]) -> [String] {
var index = startIndex
let iterator: AnyIterator<String> = AnyIterator {
defer { index = self.index(index, offsetBy: 1) }
guard index < self.endIndex, index < numberArray.endIndex else { return nil }
return self[index] + String(numberArray[index])
}
return Array(iterator)
}
}
let letterArray = ["a", "b", "c", "d", "e"]
let numberArray = [1, 2, 3, 4, 5, 6, 7]
let newArray = letterArray.mergeLettersWithNumbers(from: numberArray)
print(newArray) // prints ["a1", "b2", "c3", "d4", "e5"]
.1) }
print(finalArray) // prints ["a1", "b2", "c3", "d4", "e5"]
.index])
} as [String]
.element + String(numberArray[##代码##.index]) }
+ String() }
print(result) // => ["a1", "b2", "c3", "d4", "e5"]
zip(_:_:)produces a custom Zip2Sequence, which has a special implmentation of the SequenceTypeprotocol, so that it iterates pairs made from the two source collections.
zip(_:_:)生成一个 custom Zip2Sequence，它具有SequenceType协议的特殊实现，以便它迭代由两个源集合组成的对。
回答by fpg1503
Actually you cando it using only map!
实际上你可以只使用map!
If the two sequences have the same size just enumerateand map:
如果两个序列的大小相同，则enumerate和map：
If you're not sure which one is larger and you wanna trim using the smaller just flatMapthe undesired values away:
如果您不确定哪个更大并且您想使用较小flatMap的值来修剪不需要的值：
回答by Imanou Petit
#1. Using zip(_:_:)to combine elements of an array of Stringwith elements of an array of Intinto a new array of String
#1. 使用zip(_:_:)到的阵列的元素结合String使用的阵列的元素Int到一个新的数组String
With Swift 3, Swift Standard Library provides zip(_:_:)function. zip(_:_:)has the following declaration:
在 Swift 3 中，Swift 标准库提供了zip(_:_:)功能。zip(_:_:)有以下声明：
Creates a sequence of pairs built out of two underlying sequences.
创建由两个底层序列构建的对序列。
In order to get a new array from a Zip2Sequenceinstance, you can use Zip2Sequence's map(_:)method. The Playground code below that uses map(_:)combines your letter and number elements into a new array of String:
为了从Zip2Sequence实例中获取新数组，您可以使用Zip2Sequence'smap(_:)方法。下面使用的 Playground 代码map(_:)将您的字母和数字元素组合成一个新的 数组String：
You can refactor the previous code with a much concise style:
你可以用更简洁的风格重构之前的代码：
##代码##As an alternative to map(_:), you can use Zip2Sequence's reduce(_:_:)method:
作为 的替代方法map(_:)，您可以使用Zip2Sequence的reduce(_:_:)方法：
#2. Using an Arrayextension custom method to combine elements of an array of Stringwith elements of an array of Intinto a new array of String
#2. 使用Array扩展自定义方法将数组的String元素与数组的元素组合Int成一个新的数组String
If you don't want to use zip(_:_:), you can create your own Arrayextension method in order to have the expected result. The Playground code below shows how to create it:
如果您不想使用zip(_:_:)，您可以创建自己的Array扩展方法以获得预期的结果。下面的 Playground 代码显示了如何创建它：
