VBA array sort function?

Question

I\'m looking for a decent sort implementation for arrays in VBA. A Quicksort would be preferred. Or any other sort algorithm other than bubble or merge would suffice.

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Answer 1

Heapsort implementation. An O(n log(n)) (both average and worst case), in place, unstable sorting algorithm.

Use with: Call HeapSort(A), where A is a one dimensional array of variants, with Option Base 1.

Sub SiftUp(A() As Variant, I As Long)
    Dim K As Long, P As Long, S As Variant
    K = I
    While K > 1
        P = K \ 2
        If A(K) > A(P) Then
            S = A(P): A(P) = A(K): A(K) = S
            K = P
        Else
            Exit Sub
        End If
    Wend
End Sub

Sub SiftDown(A() As Variant, I As Long)
    Dim K As Long, L As Long, S As Variant
    K = 1
    Do
        L = K + K
        If L > I Then Exit Sub
        If L + 1 <= I Then
            If A(L + 1) > A(L) Then L = L + 1
        End If
        If A(K) < A(L) Then
            S = A(K): A(K) = A(L): A(L) = S
            K = L
        Else
            Exit Sub
        End If
    Loop
End Sub

Sub HeapSort(A() As Variant)
    Dim N As Long, I As Long, S As Variant
    N = UBound(A)
    For I = 2 To N
        Call SiftUp(A, I)
    Next I
    For I = N To 2 Step -1
        S = A(I): A(I) = A(1): A(1) = S
        Call SiftDown(A, I - 1)
    Next
End Sub

Answer 2

I wonder what would you say about this array sorting code. It's quick for implementation and does the job ... haven't tested for large arrays yet. It works for one-dimensional arrays, for multidimensional additional values re-location matrix would need to be build (with one less dimension that the initial array).

       For AR1 = LBound(eArray, 1) To UBound(eArray, 1)
            eValue = eArray(AR1)
            For AR2 = LBound(eArray, 1) To UBound(eArray, 1)
                If eArray(AR2) < eValue Then
                    eArray(AR1) = eArray(AR2)
                    eArray(AR2) = eValue
                    eValue = eArray(AR1)
                End If
            Next AR2
        Next AR1

Answer 3

Take a look here:
Edit: The referenced source (allexperts.com) has since closed, but here are the relevant author comments:

There are many algorithms available on the web for sorting. The most versatile and usually the quickest is the Quicksort algorithm. Below is a function for it.

Call it simply by passing an array of values (string or numeric; it doesn't matter) with the Lower Array Boundary (usually 0) and the Upper Array Boundary (i.e. UBound(myArray).)

Example: Call QuickSort(myArray, 0, UBound(myArray))

When it's done, myArray will be sorted and you can do what you want with it.
_{(Source: archive.org)}

Public Sub QuickSort(vArray As Variant, inLow As Long, inHi As Long)
  Dim pivot   As Variant
  Dim tmpSwap As Variant
  Dim tmpLow  As Long
  Dim tmpHi   As Long

  tmpLow = inLow
  tmpHi = inHi

  pivot = vArray((inLow + inHi) \ 2)

  While (tmpLow <= tmpHi)
     While (vArray(tmpLow) < pivot And tmpLow < inHi)
        tmpLow = tmpLow + 1
     Wend

     While (pivot < vArray(tmpHi) And tmpHi > inLow)
        tmpHi = tmpHi - 1
     Wend

     If (tmpLow <= tmpHi) Then
        tmpSwap = vArray(tmpLow)
        vArray(tmpLow) = vArray(tmpHi)
        vArray(tmpHi) = tmpSwap
        tmpLow = tmpLow + 1
        tmpHi = tmpHi - 1
     End If
  Wend

  If (inLow < tmpHi) Then QuickSort vArray, inLow, tmpHi
  If (tmpLow < inHi) Then QuickSort vArray, tmpLow, inHi
End Sub

Note that this only works with single-dimensional (aka "normal"?) arrays. (There's a working multi-dimensional array QuickSort here.)

Answer 4

I think my code (tested) is more "educated", assuming the simpler the better.

Option Base 1

'Function to sort an array decscending
Function SORT(Rango As Range) As Variant
    Dim check As Boolean
    check = True
    If IsNull(Rango) Then
        check = False
    End If
    If check Then
        Application.Volatile
        Dim x() As Variant, n As Double, m As Double, i As Double, j As Double, k As Double
        n = Rango.Rows.Count: m = Rango.Columns.Count: k = n * m
        ReDim x(n, m)
        For i = 1 To n Step 1
            For j = 1 To m Step 1
                x(i, j) = Application.Large(Rango, k)
                k = k - 1
            Next j
        Next i
        SORT = x
    Else
        Exit Function
    End If
End Function

Answer 5

Somewhat related, but I was also looking for a native excel VBA solution since advanced data structures (Dictionaries, etc.) aren't working in my environment. The following implements sorting via a binary tree in VBA:

• Assumes array is populated one by one
• Removes duplicates
• Returns a separated string ("0|2|3|4|9") which can then be split.

I used it for returning a raw sorted enumeration of rows selected for an arbitrarily selected range

Private Enum LeafType: tEMPTY: tTree: tValue: End Enum
Private Left As Variant, Right As Variant, Center As Variant
Private LeftType As LeafType, RightType As LeafType, CenterType As LeafType
Public Sub Add(x As Variant)
    If CenterType = tEMPTY Then
        Center = x
        CenterType = tValue
    ElseIf x > Center Then
        If RightType = tEMPTY Then
            Right = x
            RightType = tValue
        ElseIf RightType = tTree Then
            Right.Add x
        ElseIf x <> Right Then
            curLeaf = Right
            Set Right = New TreeList
            Right.Add curLeaf
            Right.Add x
            RightType = tTree
        End If
    ElseIf x < Center Then
        If LeftType = tEMPTY Then
            Left = x
            LeftType = tValue
        ElseIf LeftType = tTree Then
            Left.Add x
        ElseIf x <> Left Then
            curLeaf = Left
            Set Left = New TreeList
            Left.Add curLeaf
            Left.Add x
            LeftType = tTree
        End If
    End If
End Sub
Public Function GetList$()
    Const sep$ = "|"
    If LeftType = tValue Then
        LeftList$ = Left & sep
    ElseIf LeftType = tTree Then
        LeftList = Left.GetList & sep
    End If
    If RightType = tValue Then
        RightList$ = sep & Right
    ElseIf RightType = tTree Then
        RightList = sep & Right.GetList
    End If
    GetList = LeftList & Center & RightList
End Function

'Sample code
Dim Tree As new TreeList
Tree.Add("0")
Tree.Add("2")
Tree.Add("2")
Tree.Add("-1")
Debug.Print Tree.GetList() 'prints "-1|0|2"
sortedList = Split(Tree.GetList(),"|")

Answer 6

I posted some code in answer to a related question on StackOverflow:

Sorting a multidimensionnal array in VBA

The code samples in that thread include:

1. A vector array Quicksort;
2. A multi-column array QuickSort;
3. A BubbleSort.

Alain's optimised Quicksort is very shiny: I just did a basic split-and-recurse, but the code sample above has a 'gating' function that cuts down on redundant comparisons of duplicated values. On the other hand, I code for Excel, and there's a bit more in the way of defensive coding - be warned, you'll need it if your array contains the pernicious 'Empty()' variant, which will break your While... Wend comparison operators and trap your code in an infinite loop.

Note that quicksort algorthms - and any recursive algorithm - can fill the stack and crash Excel. If your array has fewer than 1024 members, I'd use a rudimentary BubbleSort.

Public Sub QuickSortArray(ByRef SortArray As Variant, _
                                Optional lngMin As Long = -1, _ 
                                Optional lngMax As Long = -1, _ 
                                Optional lngColumn As Long = 0)
On Error Resume Next

'Sort a 2-Dimensional array

' Sample Usage: sort arrData by the contents of column 3
'
'   QuickSortArray arrData, , , 3

'
'Posted by Jim Rech 10/20/98 Excel.Programming

'Modifications, Nigel Heffernan:

'       ' Escape failed comparison with empty variant
'       ' Defensive coding: check inputs

Dim i           As Long
Dim j           As Long
Dim varMid      As Variant
Dim arrRowTemp  As Variant
Dim lngColTemp  As Long


 If IsEmpty(SortArray) Then
     Exit Sub
 End If

 If InStr(TypeName(SortArray), "()") < 1 Then  'IsArray() is somewhat broken:  Look for brackets in the type name
     Exit Sub
 End If

 If lngMin = -1 Then
     lngMin = LBound(SortArray, 1)
 End If
 
 If lngMax = -1 Then
     lngMax = UBound(SortArray, 1)
 End If
 
 If lngMin >= lngMax Then ' no sorting required
     Exit Sub
 End If


 i = lngMin
 j = lngMax

 varMid = Empty
 varMid = SortArray((lngMin + lngMax) \ 2, lngColumn)

 ' We  send 'Empty' and invalid data items to the end of the list:
 If IsObject(varMid) Then  ' note that we don't check isObject(SortArray(n)) - varMid might pick up a valid default member or property
     i = lngMax
     j = lngMin
 ElseIf IsEmpty(varMid) Then
     i = lngMax
     j = lngMin
 ElseIf IsNull(varMid) Then
     i = lngMax
     j = lngMin
 ElseIf varMid = "" Then
     i = lngMax
     j = lngMin
 ElseIf varType(varMid) = vbError Then
     i = lngMax
     j = lngMin
 ElseIf varType(varMid) > 17 Then
     i = lngMax
     j = lngMin
 End If


 While i <= j

     While SortArray(i, lngColumn) < varMid And i < lngMax
         i = i + 1
     Wend

     While varMid < SortArray(j, lngColumn) And j > lngMin
         j = j - 1
     Wend


     If i <= j Then

         ' Swap the rows
         ReDim arrRowTemp(LBound(SortArray, 2) To UBound(SortArray, 2))
         For lngColTemp = LBound(SortArray, 2) To UBound(SortArray, 2)
             arrRowTemp(lngColTemp) = SortArray(i, lngColTemp)
             SortArray(i, lngColTemp) = SortArray(j, lngColTemp)
             SortArray(j, lngColTemp) = arrRowTemp(lngColTemp)
         Next lngColTemp
         Erase arrRowTemp

         i = i + 1
         j = j - 1

     End If


 Wend

 If (lngMin < j) Then Call QuickSortArray(SortArray, lngMin, j, lngColumn)
 If (i < lngMax) Then Call QuickSortArray(SortArray, i, lngMax, lngColumn)

 
End Sub