Filtering duplicates in array and deleting array elements from another array in swift 2.0

Question

I'm trying to delete duplicate elements of type [(Int,Int)] from an array, then I'm trying to delete an array of elements of same type from parent array. This is how I do it.

func filterDuplicatesFrom(var buttonArray:[(Int,Int)]) ->[(Int,Int)]
    {
        var i: Int = 0, j:Int = 0
        var elementToDelete:[Int] = []
        for (i=0; i<buttonArray.count-1; i++)
        {
            for (j=i+1; j<buttonArray.count; j++)
            {
                if buttonArray[j].0 == buttonArray[i].0 &&  buttonArray[j].1 == buttonArray[i].1
                {
                    if elementToDelete.contains(j)
                    {
                        elementToDelete.append(j)
                    }
                }
            }
        }

        buttonArray.removeAtIndices(elementToDelete)
    }

func deletePoints(var deleteList:[(Int,Int)],var buttonArray:[(Int,Int)]) ->[(Int,Int)]
{

    var i: Int = 0, j:Int = 0
    var elementToDelete:[Int] = []
    for (i=0; i<buttonArray.count; i++)
    {
        for (j=0; j<deleteList.count; j++)
        {
            if deleteList[j].0 == buttonArray[i].0 &&  deleteList[j].1 == buttonArray[i].1
            {
                if elementToDelete.contains(i)
                {
                    elementToDelete.append(i)
                }
            }
        }
    }

    buttonArray.removeAtIndices(elementToDelete)
}

extension Array {
    mutating func removeAtIndices(incs: [Int]) {
        incs.sort(>).map { removeAtIndex($0) }
    }

This seems to work, but I wonder if it would effect the performance for large number of data. Is there a better way to do this? or what I've done is correct?

xlogic · Accepted Answer · 2015-11-26 10:47:47Z

2

You could replace the tuple with a struct that conforms to Hashable protocol.

struct Button: Hashable {
    ...
}

Then if you have an array of instances of this struct you can use Sets to filter duplicates and subtract one set from the other. Sets are a collection of unordered unique elements.

/// remove duplicates (create a set)

func filterDuplicatesFrom(buttonArray:[Button]) -> Set<Button> {
    return Set(buttonArray)
}

/// delete

func deletePoints(deleteList:[Button], buttonArray:[Button]) -> Set<Button> {
    return Set(buttonArray).subtract(Set(deleteList))
}

edited Nov 26, 2015 at 10:47

answered Nov 26, 2015 at 10:36

xlogic

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