Sorting Arrays Swift

Question

I have an array of integers that represent their own strings.

I know there are simple ways to sort integer arrays, but I needed to make it so that the integers retain their correspondence to the strings.

Here is my current code:

var i = 0
var highestValueObjectInArray = 0
for object in createTimerData.speechTimeStamps {

    if object > highestValueObjectInArray {
        highestValueObjectInArray = object
    }

}

while i + 1 < createTimerData.speechTimeStamps.count {

    if createTimerData.speechTimeStamps[i] < createTimerData.speechTimeStamps[i + 1] {

        let TS2 = createTimerData.speechTimeStamps[i + 1]
        let TSS2 = createTimerData.speechText[i + 1]

        createTimerData.speechTimeStamps.remove(at: i + 1)
        createTimerData.speechTimeStamps.insert(TS2, at: i)
        createTimerData.speechText.remove(at: i + 1)
        createTimerData.speechText.insert(TSS2, at: i)

    }

    i += 1
    if i+1 >= createTimerData.speechTimeStamps.count {

        var lastItem = highestValueObjectInArray + 1
        var inDescendingOrder = true
        for object in createTimerData.speechTimeStamps {
            if object < lastItem {} else { inDescendingOrder = false }
            lastItem = object
        }
        if inDescendingOrder == false {
            i = 0
        }
    }
}

It is very slow and not very efficient so when it sorts large arrays it takes a large amount of time. Is there a way I have overlooked, or a way that is more efficient.

Any help would be much appreciated, thanks.

use an array and a dictionary to do this, or even an array of tuples — Reinier Melian
– Reinier Melian, Commented Jan 5, 2018 at 8:54
You are trying to sort an array of what? can you explain a little bit more? — Reinier Melian
– Reinier Melian, Commented Jan 5, 2018 at 8:56
An array of integers, and I want the strings array to follow the same sorting, so that the integers and strings still match each other — D-A UK
– D-A UK, Commented Jan 5, 2018 at 8:58
you can do this using an array of tuples (int,String), I can provide some example if you need to — Reinier Melian
– Reinier Melian, Commented Jan 5, 2018 at 9:02

Rob · Accepted Answer · 2018-01-05 09:23:27Z

3

Often, when you want to sort separate arrays alongside each other, you should really consider merging them into a single array of a custom type. For example, speechText and speechTimestamps might merged into an array of a single type, Speech:

struct Speech { 
    let text: String
    let timestamp: Int
}

let speeches = [
    Speech(text: "Baz", timestamp: 2),
    Speech(text: "Bar", timestamp: 3),
    Speech(text: "Foo", timestamp: 1)
]

Then you can sort these as you see fit:

let result = speeches.sorted { $0.timestamp < $1.timestamp }

Clearly, modify the types and the names as appropriate, but hopefully this will illustrate the idea. Consider a single array of a type that captures both things being sorted.

answered Jan 5, 2018 at 9:23

Rob

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Malik · Accepted Answer · 2018-01-05 09:03:14Z

2

You can zip the two arrays together, sort the zipped array, and then separate them like below

let arr1 = [1,4,2,5,3]
let arr2 = ["One","Four","Two","Five","Three"]

let combined = zip(arr1, arr2).sorted(by: {
    $0.0 < $1.0
})

let sorted1 = combined.map {$0.0}
let sorted2 = combined.map {$0.1}

print(sorted1) // [1, 2, 3, 4, 5]
print(sorted2) // ["One", "Two", "Three", "Four", "Five"]

answered Jan 5, 2018 at 9:03

Malik

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2 Comments

D-A UK Over a year ago

This is amazing thank you, except I want it to sort in descending order - how do I do this?

D-A UK Over a year ago

Never mind, did: $1.0 < $0.0, instead of $0.0 < $1.0

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