如何检查数组中是否有重复值？

Question

var arrEmails = NSMutableArray()
arrEmails = ["[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"]

上面是我的数组，我想检查是否有重复的值。为此我写了下面的代码。

let set = NSCountedSet.init(array: arrEmails as! [Any])
        var duplicates: Int = 0

        for var object in set {
            if set.count(for: object) > 1 {
                duplicates = duplicates+1
            }
        }

但是在上面的代码中，如果数组包含如下所示的值，那么它会返回重复值 1。

arrEmails = ["[email protected]", "", "", "[email protected]", "", ""]

我不想删除重复值，我只想检查数组中重复值的数量。 怎样可以检查呢？请帮帮我。

Answer 1

首先停止使用

NSMutableArray

并使用 Swift 数组。

所以你有这个数组

let emails = ["[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"]

现在您只需输入即可检查是否有重复

let hasDuplicates = emails.count != Set(emails).count

注意，只有当数组的泛型类型为

Hashable

时，这才有效。

Answer 2

您的代码计算不同重复项的数量。在您的情况下，所有四个重复项彼此相同 - 即空字符串

""

。

如果要计算具有重复项的对象总数，请将

set.count(for: object)

返回的值相加：

let arrEmails = ["[email protected]", "", "", "[email protected]", "", ""]
let set = NSCountedSet.init(array: arrEmails as! [Any])
let totalDups = set.map { set.count(for: $0) }.filter {$0 > 1}.reduce(0, +)

上面的代码生成

totalDups

of

4

。

用于计算唯一重复项的代码可以减少为一行，如下所示：

let uniqueDups = set.map { set.count(for: $0) }.filter {$0 > 1}.count

Answer 3

SWIFT 4

肯定有更好的方法来做到这一点，但我有一个用来解决此类问题的方法

这已经过测试，您可以将此代码粘贴到 Playground 中以获得即时结果

    // here we can store dulicate elements in array
    var storeDuplicateValue =  [String:Int]()
    let arrEmails = ["[email protected]", "", "", "[email protected]", "", "","[email protected]"]
        var count = 0
       // here we loop through all elements
        for email in arrEmails {
          if(email != ""){
        count = 0
         for newEmail in arrEmails {
       if(email == newEmail){
          count += 1

        }
    }
    // if count is more than 1 we have duplicate elements
    if(count > 1){
        // so we store duplicate elements in dictionary and its count to know how many times it has been repeated
        storeDuplicateValue.updateValue(count, forKey: email)
    }
}
}

print(storeDuplicateValue)
// here we get count of keys in dictionary to know number of duplicate strings
print(storeDuplicateValue.keys.count)

Answer 4

你的代码没问题！您得到了正确且预期的结果！

如您的代码中所示，重复的值是“”。

为了更好地理解，您可以更改值数组并重试。

Answer 5

正如大多数其他答案所述，您的代码很好。如果唯一的问题是应该忽略空字符串，您可以在计算重复项之前从数组中过滤掉它们：

let emails = ["[email protected]", "", "", "[email protected]", "", ""]
let emailsWithoutEmptyStrings = emails.filter { $0 != "" }
let set = NSCountedSet(array: emailsWithoutEmptyStrings)
var duplicates = 0

for object in set {
  if set.count(for: object) > 1 {
    duplicates += 1
  }
}

Answer 6

extension Array where Element: Hashable {
    var asSet: Set<Element> {
        return Set(self)
    }
    
    var hasDuplicates: Bool {
        return self.count > self.asSet.count
    }
}

let someArray = ["kiwi", "mango", "kiwi"]

if someArray.hasDuplicates {
    print("has duplicates")
} else {
    print("no duplicates")
}