我可能有一个像下面这样的数组:

[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的序列。我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:

[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中只有一个。Swift是否提供了一种容易做到这一点的方法,还是我必须自己做?


当前回答

斯威夫特4. x:

extension Sequence where Iterator.Element: Hashable {
  func unique() -> [Iterator.Element] {
    return Array(Set<Iterator.Element>(self))
  }

  func uniqueOrdered() -> [Iterator.Element] {
    return reduce([Iterator.Element]()) { $0.contains($1) ? $0 : $0 + [$1] }
  }
}

用法:

["Ljubljana", "London", "Los Angeles", "Ljubljana"].unique()

or

["Ljubljana", "London", "Los Angeles", "Ljubljana"].uniqueOrdered()

其他回答

您总是可以使用Dictionary,因为Dictionary只能保存惟一的值。例如:

var arrayOfDates: NSArray = ["15/04/01","15/04/01","15/04/02","15/04/02","15/04/03","15/04/03","15/04/03"]

var datesOnlyDict = NSMutableDictionary()
var x = Int()

for (x=0;x<(arrayOfDates.count);x++) {
    let date = arrayOfDates[x] as String
    datesOnlyDict.setValue("foo", forKey: date)
}

let uniqueDatesArray: NSArray = datesOnlyDict.allKeys // uniqueDatesArray = ["15/04/01", "15/04/03", "15/04/02"]

println(uniqueDatesArray.count)  // = 3

正如你所看到的,生成的数组并不总是按“顺序”排列。如果你想对数组排序,添加这个:

var sortedArray = sorted(datesOnlyArray) {
(obj1, obj2) in

    let p1 = obj1 as String
    let p2 = obj2 as String
    return p1 < p2
}

println(sortedArray) // = ["15/04/01", "15/04/02", "15/04/03"]

.

这只是一个非常简单和方便的实现。具有相等元素的数组扩展中的计算属性。

extension Array where Element: Equatable {
    /// Array containing only _unique_ elements.
    var unique: [Element] {
        var result: [Element] = []
        for element in self {
            if !result.contains(element) {
                result.append(element)
            }
        }

        return result
    }
}

包含相等性检查,而插入检查哈希,最安全的检查方式如下:

extension Array where Element: Hashable {

    /// Big O(N) version. Updated since @Adrian's comment. 
    var uniques: Array {
        // Go front to back, add element to buffer if it isn't a repeat.
         var buffer: [Element] = []
         var dictionary: [Element: Int] = [:]
         for element in self where dictionary[element] == nil {
             buffer.append(element)
             dictionary[element] = 1
         }
         return buffer
    }
}

从数组中删除重复项的简单方法

extension Array where Element: Equatable {
mutating func removeDuplicates() {
    var result = [Element]()
    for value in self {
        if !result.contains(value) {
            result.append(value)
        }
    }
    self = result
}}

如果你想保持秩序,那么就用这个

let fruits = ["apple", "pear", "pear", "banana", "apple"] 
let orderedNoDuplicates = Array(NSOrderedSet(array: fruits).map({ $0 as! String }))