CODEWITHSUNDEEP
iosswiftxcode
mushy
mushy

Reputation: 43

Remove duplicates from array of dictionaries, Swift 3

Problem

I have an array of dictionaries as follows:

var arrayOfDicts = [
    ["Id":"01", "Name":"Alice", "Age":"15"]
    ["Id":"02", "Name":"Bob", "Age":"53"]
    ["Id":"03", "Name":"Cathy", "Age":"12"]
    ["Id":"04", "Name":"Bob", "Age":"83"]
    ["Id":"05", "Name":"Denise", "Age":"88"]
    ["Id":"06", "Name":"Alice", "Age":"44"]
]

I need to remove all dictionaries where there is a duplicate name. For instance, I need an output of:

var arrayOfDicts = [
    ["Id":"01", "Name":"Alice", "Age":"15"]
    ["Id":"02", "Name":"Bob", "Age":"53"]
    ["Id":"03", "Name":"Cathy", "Age":"12"]
    ["Id":"05", "Name":"Denise", "Age":"88"]
]

Order does not need to be preserved.

Attempted Solution

for i in 0..<arrayOfDicts.count
{
    let name1:String = arrayOfDicts[i]["Name"]

    for j in 0..<arrayOfDicts.count
    {
        let name2:String = arrayOfDicts[j]["Name"]

        if (i != j) && (name1 == name2)
        {
            arrayOfDicts.remove(j)
        }
    }
}

This crashes though, I believe since I am modifying the size of arrayOfDicts, so eventually it j is larger than the size of the array.

If someone could help me out, that would be much appreciated.

Upvotes: 3

Views: 8432

Answers (7)

Leo Dabus
Leo Dabus

Reputation: 236315

You can use a set to control which dictionaries to add to the resulting array. The approach it is very similar to the one used in these answer and this

let array: [[String : Any]] = [["Id":"01", "Name":"Alice", "Age":"15"],
                                ["Id":"02", "Name":"Bob", "Age":"53"],
                                ["Id":"03", "Name":"Cathy", "Age":"12"],
                                ["Id":"04", "Name":"Bob", "Age":"83"],
                                ["Id":"05", "Name":"Denise", "Age":"88"],
                                ["Id":"06", "Name":"Alice", "Age":"44"]]

var set = Set<String>()
let arraySet: [[String: Any]] = array.compactMap {
    guard let name = $0["Name"] as? String else { return nil }
    return set.insert(name).inserted ? $0 : nil
}

arraySet   // [["Name": "Alice", "Age": "15", "Id": "01"], ["Name": "Bob", "Age": "53", "Id": "02"], ["Name": "Cathy", "Age": "12", "Id": "03"], ["Name": "Denise", "Age": "88", "Id": "05"]]

Upvotes: 10

janusfidel
janusfidel

Reputation: 8106

If you don't mind using an additional list:

var uniqueArray = [[String: String]]()
for item in arrayOfDicts {
    let exists =  uniqueArray.contains{ element in
        return element["Name"]! == item["Name"]!
    }
    if !exists {
      uniqueArray.append(item)
    }
}

Upvotes: 0

Dominic Bett
Dominic Bett

Reputation: 506

Try this:

var uniqueNames = [String: [String:String] ]()

for air in arrayOfDicts {
    if (uniqueNames[arr["Name"]!] == nil) {
        uniqueNames[arr["Name"]!] = arr
    }
}

result = Array(uniqueNames.values)

Upvotes: 0

Fogmeister
Fogmeister

Reputation: 77631

let uniqueArray = Array(Set(yourArrayWithDuplicates))

That should do the trick.

If you want to use just the name for uniqueness then create these as structs.

You shouldn't be doing anything with dictionaries. Much easier to work with data that makes sense.

Upvotes: 0

ghostatron
ghostatron

Reputation: 2650

Several good answers already, but it was a fun exercise, so here's my solution. I'm assuming you don't care which of the duplicate entries are kept (this will keep the last one of the dupes).

func noDuplicates(arrayOfDicts: [[String:String]]) -> [[String:String]]
{
    var noDuplicates: [String:[String:String]] = [:]
    for dict in arrayOfDicts
    {
        if let name = dict["name"]
        {
            noDuplicates[name] = dict
        }
    }

    // Returns just the values of the dictionary
    return Array(noDuplicates.values.map{ $0 })
}

Upvotes: 0

schinj
schinj

Reputation: 804

Please check this answer:

var arrayOfDicts = [
    ["Id":"01", "Name":"Alice", "Age":"15"],
    ["Id":"02", "Name":"Bob", "Age":"53"],
    ["Id":"03", "Name":"Cathy", "Age":"12"],
    ["Id":"04", "Name":"Bob", "Age":"83"],
    ["Id":"05", "Name":"Denise", "Age":"88"],
    ["Id":"06", "Name":"Alice", "Age":"44"]
]

var answerArray = [[String:String]]()

for i in 0..<arrayOfDicts.count
{
    let name1 = arrayOfDicts[i]["Name"]
    if(i == 0){
        answerArray.append(arrayOfDicts[i])
    }else{
        var doesExist = false
        for j in 0..<answerArray.count
        {
            let name2:String = answerArray[j]["Name"]!
            if name1 == name2 {
                doesExist = true
            }
        }
        if(!doesExist){
            answerArray.append(arrayOfDicts[i])
        }
    }
}

Upvotes: 1

Connor Neville
Connor Neville

Reputation: 7351

I definitely recommend having a new copy rather than modifying the initial array. I also create storage for names already used, so you should only need to loop once.

func noDuplicates(_ arrayOfDicts: [[String: String]]) -> [[String: String]] {
    var noDuplicates = [[String: String]]()
    var usedNames = [String]()
    for dict in arrayOfDicts {
        if let name = dict["name"], !usedNames.contains(name) {
            noDuplicates.append(dict)
            usedNames.append(name)
        }
    }
    return noDuplicates
}

Upvotes: 13

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