从 Swift 中的数组中删除重复元素 [英] Removing duplicate elements from an array in Swift

问题描述

我可能有一个如下所示的数组:

I might have an array that looks like the following:

[1, 4, 2, 2, 6, 24, 15, 2, 60, 15, 6]

或者，实际上，任何类似类型的数据部分序列.我想要做的是确保每个相同的元素只有一个.例如，上面的数组将变成:

Or, really, any sequence of like-typed portions of data. What I want to do is ensure that there is only one of each identical element. For example, the above array would become:

[1, 4, 2, 6, 24, 15, 60]

请注意，删除了 2、6 和 15 的重复项以确保每个相同的元素只有一个.Swift 是否提供了一种轻松完成此操作的方法，还是我必须自己完成?

Notice that the duplicates of 2, 6, and 15 were removed to ensure that there was only one of each identical element. Does Swift provide a way to do this easily, or will I have to do it myself?

推荐答案

您可以推出自己的方案，例如像这样:

You can roll your own, e.g. like this:

func unique<S : Sequence, T : Hashable>(source: S) -> [T] where S.Iterator.Element == T {
    var buffer = [T]()
    var added = Set<T>()
    for elem in source {
        if !added.contains(elem) {
            buffer.append(elem)
            added.insert(elem)
        }
    }
    return buffer
}

let vals = [1, 4, 2, 2, 6, 24, 15, 2, 60, 15, 6]
let uniqueVals = uniq(vals) // [1, 4, 2, 6, 24, 15, 60]

并作为Array的扩展:

extension Array where Element: Hashable {
    func uniqued() -> Array {
        var buffer = Array()
        var added = Set<Element>()
        for elem in self {
            if !added.contains(elem) {
                buffer.append(elem)
                added.insert(elem)
            }
        }
        return buffer
    }
}

或者更优雅(Swift 4/5):

Or more elegantly (Swift 4/5):

extension Sequence where Element: Hashable {
    func uniqued() -> [Element] {
        var set = Set<Element>()
        return filter { set.insert($0).inserted }
    }
}

将用于:

[1,2,4,2,1].uniqued()  // => [1,2,4]

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