How to sort a dictionary based on keys and sort its respective values in Swift

Question

I have a dictionary with string as key and an array of int as values , i need to sort the dictionary based on keys and the array value should also be sorted.

var dicNumArray : Dictionary<String , [Int]> = ["q":[4,3,2,1,5],"a":[2,3,4,5,5],"s":[123,123,132,43,4],"t":[0,88,66,542,321]]

The result i need is the dictionary itself where it is sorted by keys and respective values are also sorted.

What type of output are you expecting? Are you printing something, or creating a new data structure (an array for instance?) Have you had trouble with the `.sorted` method? — Rob Napier, May 11 '18 at 03:55
dictionaries have no order. check this out: https://stackoverflow.com/a/29603477/6642629 — koropok, May 11 '18 at 03:57

Sam · Answer 1 · 2018-05-11T04:21:14.670

You can apply sorted to each the value of the key-value pair of a dictionary using mapValues

And then, you can just use sorted with a predicate comparing the keys of the dictionary.

let result = dicNumArray.mapValues { $0.sorted() }
                        .sorted { $0.key < $1.key }

This will return an array of key-value pair tuples.

Since, dictionaries can't be trusted with order, working with an array of the key-value pairs is the next best approach.

We can use .key and .value to get the respective values.

result.first?.key     // First key
result.first?.value   // First value

Abdelahad Darwish · Answer 2 · 2018-05-11T04:27:11.867

1

you can apply sort key , then map to sorted by array

let sortedKeysAndValues = dicNumArray.sorted(by: {$0.0 < $1.0}).map { [$0.key:$0.value.sorted(by: <)]}.flatMap({$0})

edited May 11 '18 at 04:27

answered May 11 '18 at 04:09

Abdelahad Darwish

5,969
1
17
35

This returns as an array , how do i get this as dictionary itself – Nassif May 11 '18 at 04:12
Its dictionary `[:]` – Abdelahad Darwish May 11 '18 at 04:13
1

@AbdelahadDarwish : it never return dictionary, it will return array of sorted tuple – Abhishek Thapliyal May 11 '18 at 04:14

score 1 · Answer 3 · answered May 11 '18 at 04:10

Dictionaries don't have an order in Swift. Having said that, you can do something like this

var dicNumArray : Dictionary<String , [Int]> = ["q":[4,3,2,1,5],"a":[2,3,4,5,5],"s":[123,123,132,43,4],"t":[0,88,66,542,321]]

func sortData() {
    for (key, value) in dicNumArray {
        dicNumArray[key] = value.sorted(by: { $0 < $1 })
    }
}

sortData()

This will sort array for each key. Once that's done, you can do something like

let keys = Array(dicNumArray.keys).sorted(by: { $0 < $1 })

This will give you a sorted array of dictionary keys. You can test it as follows

TEST

for key in keys {
    print("\(key): \(dicNumArray[key]!)")
}

OUTPUT

a: [2, 3, 4, 5, 5]
q: [1, 2, 3, 4, 5]
s: [4, 43, 123, 123, 132]
t: [0, 66, 88, 321, 542]

How to sort a dictionary based on keys and sort its respective values in Swift

3 Answers3