Remove item from Array at Specific Index - excel

Question

I have an array of numbers, once i "use" a number I want to remove using a specific index I have stored for that value.
I know there is no direct method but is there a way I work around this?
Example:
ShiftArray(1,25,12)
Pos = 1
Shiftarray(pos).delete
The array then should be = ShiftArray(1,12)
(I know such a method does not exist, just for clarity of intention's sake)
I tried the following but it gave me an error:
ShiftHeadsArray(pos - 1) = " "
StringUse = Application.WorksheetFunction.Trim(Join(ShiftHeadsArray, " "))
ShiftHeadsArray = Split(StringUse, " ")
Where pos is the position of the number I want to remove within the array.

Answer 1

Try this code
Sub Test()
Dim arr
arr = Array(1, 25, 12)
DeleteItem arr, 1
Debug.Print Join(arr, ", ")
End Sub
Sub DeleteItem(ByRef arr, v)
Dim a(), i As Long, n As Long, x As Long, y As Long
x = LBound(arr): y = UBound(arr)
ReDim a(x To y)
For i = x To y
If i <> v Then a(i - n) = arr(i) Else n = n + 1
Next i
If (y - n) >= x Then ReDim Preserve a(x To y - n)
arr = a
End Sub

Answer 2

Having a array-only based solution isn't so trivial, if you're interested in catching possible errors.
Remark: Instead of just returning an empty array or the input array like in this example, you should raise an error if the input isn't proper. But this depends on how you like the function to behave.
Public Sub Test()
'Some common tests:
Debug.Assert Join(RemoveItemByIndex(Array(), 1), "-") = vbNullString
Debug.Assert Join(RemoveItemByIndex(Array(1), 0), "-") = vbNullString
Debug.Assert Join(RemoveItemByIndex(Array(1), 1), "-") = vbNullString
Debug.Assert Join(RemoveItemByIndex(Array(1, 25, 12), 1), "-") = "1-12"
Debug.Assert Join(RemoveItemByIndex(Array(1, 25, 12), 10), "-") = "1-25-12"
Debug.Assert Join(RemoveItemByIndex(Array(1, 25, 12), -1), "-") = "1-25-12"
Debug.Assert Join(RemoveItemByIndex("foo", -1), "-") = vbNullString
'Your working sample:
Dim originalArray() As Variant
originalArray = Array(1, 25, 12)
Dim item As Variant
For Each item In RemoveItemByIndex(originalArray, 1)
Debug.Print item
Next item
End Sub
Public Function RemoveItemByIndex(ByVal arrayToWorkOn As Variant, ByVal indexToRemove As Long) As Variant()
RemoveItemByIndex = Array()
If Not IsArray(arrayToWorkOn) Then Exit Function
If Not IsArrayInitialized(arrayToWorkOn) Then Exit Function
If UBound(arrayToWorkOn) - LBound(arrayToWorkOn) = 0 Then Exit Function
RemoveItemByIndex = arrayToWorkOn
If indexToRemove < LBound(arrayToWorkOn) _
Or indexToRemove > UBound(arrayToWorkOn) Then Exit Function
ReDim resultingArray(UBound(arrayToWorkOn) - 1) As Variant
Dim index As Long
Dim resultingIndex As Long
For index = LBound(arrayToWorkOn) To UBound(arrayToWorkOn): Do
If index = indexToRemove Then Exit Do
resultingArray(resultingIndex) = arrayToWorkOn(index)
resultingIndex = resultingIndex + 1
Loop While False: Next index
RemoveItemByIndex = resultingArray
End Function
Public Function IsArrayInitialized(ByVal arrayToWorkOn As Variant) As Boolean
On Error Resume Next
IsArrayInitialized = IsArray(arrayToWorkOn) And _
Not IsError(LBound(arrayToWorkOn, 1)) And _
LBound(arrayToWorkOn, 1) <= UBound(arrayToWorkOn, 1)
End Function
Regarding the : Do and Loop While False:: This is a neat trick to simulate a 'continue'.
See here for more information: VBA - how to conditionally skip a for loop iteration

Answer 3

Remove Array Item by Index
Option Explicit
Sub TESTremoveArrayItemByIndex()
Dim Addresses As Variant: Addresses = Array("A1", "A2", "A3")
Dim Values As Variant: Values = Array(1, 25, 10)
Dim mIndex As Variant
mIndex = Application.Match(Application.Max(Values), Values, 0)
Dim dAddress As String: dAddress = Application.Index(Addresses, mIndex)
' If you are sure that 'Addresses' is zero-based, instead of the previous
' line you can do:
'Dim cAddress As String: cAddress = Addresses(Index - 1)
removeArrayItemByIndex Addresses, mIndex
Debug.Print "Addresses(After): " & Join(Addresses, ",")
removeArrayItemByIndex Values, mIndex
Debug.Print "Values(After): " & Join(Values, ",")
End Sub
Sub TESTremoveArrayItemByIndexDebugPrint()
Dim Addresses As Variant: Addresses = Array("A1", "A2", "A3")
Debug.Print "Addresses(Before): " & Join(Addresses, ",")
Dim Values As Variant: Values = Array(1, 25, 10)
Debug.Print "Values(Before): " & Join(Values, ",")
Dim mIndex As Variant
mIndex = Application.Match(Application.Max(Values), Values, 0)
Debug.Print "Maximum Index: " & mIndex
Dim dAddress As String: dAddress = Application.Index(Addresses, mIndex)
' If you are sure that 'Addresses' is zero-based, instead of the previous
' line you can do:
'Dim cAddress As String: cAddress = Addresses(Index - 1)
Debug.Print "Delete Address: " & dAddress
removeArrayItemByIndex Addresses, mIndex
Debug.Print "Addresses(After): " & Join(Addresses, ",")
removeArrayItemByIndex Values, mIndex
Debug.Print "Values(After): " & Join(Values, ",")
End Sub
Sub removeArrayItemByIndex( _
ByRef arr As Variant, _
ByVal Index As Long)
Dim n As Long
For n = Index + LBound(arr) - 1 To UBound(arr) - 1
arr(n) = arr(n + 1)
Next n
ReDim Preserve arr(LBound(arr) To n - 1)
End Sub