VBA Compare 2 arrays, write unique values to cell with comma delimiter - arrays

Question

I have a series of 2 cells in which values are separated by a comma delimiter.
Example
Cell D1 = 1,2,3,4,5,6,7,8,9,10
Cell O1 = 1,2,3,4,5,6
I want to first use the split function to pass the values to an Array and subsequently compare those 2 Arrays to find out the unique/not double values.
These values then i want to write to another cell as values with a comma delimiter.
Based on this answer
Comparing two Dimension array
and something I found about adding values to an Array i tried my luck with this code
Sub compare()
Dim cont As Long
Dim x As Long
Dim y As Long
Dim Source As Variant
Dim Comparison As Variant
Dim Target As Variant
With ThisWorkbook.Worksheets("Open items")
For cont = 1 To .Cells(Rows.Count, 4).End(xlUp).Row
Source = Split(.Range("D" & cont).Value, ",")
Comparison = Split(.Range("O" & cont).Value, ",")
For x = LBound(Source) To UBound(Source)
For y = LBound(Comparison) To UBound(Comparison)
If Source(x, y) = !Comparison(x, y) Then
Target(UBound(Target)) = Source(x, y).Value
Next
Next
Next cont
End Sub
But seem to be stuck.
Is this the correct way to add a value to the Array Target?
How do I get the Array into the cell?
The result in my example should be for Target to contain "7", "8", "9" , and "10" and should be shown in a cell in the way
7,8,9,10
Thank you for your help!

Answer 1

Some issues:
Rows.Count will look in the active sheet, not necessarily in the "Open items" sheet. So you need to add the dot: .Rows.Count
Source(x, y) will not work, since Source only has one dimension. In fact y has nothing to do with Source. A similar remark holds for Comparison.
= ! is not a valid comparison operator. You maybe intended <>.
Target is not defined, and Target(UBound(Target)) will always refer to the same location. Instead, you could append the result to a string variable immediately.
Furthermore, I would use a Collection object for fast look up, so that the algorithm is not O(n²), but O(n):
Sub Compare()
Dim cont As Long
Dim source As Variant
Dim comparison As Variant
Dim part As Variant
Dim parts As Collection
Dim result As String
With ThisWorkbook.Worksheets("Open items")
For cont = 1 To .Cells(.Rows.Count, 4).End(xlUp).Row
source = Split(.Range("D" & cont).Value, ",")
comparison = Split(.Range("O" & cont).Value, ",")
' Add the source items in a collection for faster look-up
Set parts = New Collection
For Each part In source
parts.Add Trim(part), Trim(part)
Next
' Remove the comparison items from the collection
For Each part In comparison
On Error Resume Next ' Ignore error when part is not in parts
parts.Remove Trim(part)
If Err Then parts.Add Trim(part), Trim(part) ' Add part if not yet in parts
On Error GoTo 0 ' Stop ignoring errors
Next
' Turn the remaining collection to comma-separated string
result = ""
For Each part In parts
result = result & ", " & part
Next
result = Mid(result, 3) ' Remove first comma and space
' Store the result somewhere, for example in the E column
.Range("E" & cont).Value = result
Next cont
End With
End Sub
Alternative for Sorted Lists
When your source and comparison lists are sorted in numerical order, and you need the target to maintain that sort order, you could use a tandem-kind of iteration, like this:
Sub Compare()
Dim cont As Long
Dim source As Variant
Dim comparison As Variant
Dim x As Long
Dim y As Long
Dim result As String
With ThisWorkbook.Worksheets("Open items")
For cont = 1 To .Cells(.Rows.Count, 4).End(xlUp).Row
source = Split(.Range("D" & cont).Value, ",")
comparison = Split(.Range("O" & cont).Value, ",")
x = LBound(source)
y = LBound(comparison)
result = ""
Do While x <= UBound(source) And y <= UBound(comparison)
If Val(source(x)) < Val(comparison(y)) Then
result = result & ", " & Trim(source(x))
x = x + 1
ElseIf Val(source(x)) > Val(comparison(y)) Then
result = result & ", " & Trim(comparison(y))
y = y + 1
Else
x = x + 1
y = y + 1
End If
Loop
' Flush the remainder of either source or comparison
Do While x <= UBound(source)
result = result & ", " & Trim(source(x))
x = x + 1
Loop
Do While y <= UBound(comparison)
result = result & ", " & Trim(comparison(y))
y = y + 1
Loop
result = Mid(result, 3) ' Remove first comma and space
' Store the result somewhere, for example in the E column
.Range("E" & cont).Value = result
Next cont
End With
End Sub

Answer 2

Try this small UDF():
Public Function unikue(BigString As String, LittleString As String) As String
Dim B As Variant, L As Variant, Barr, Larr
Dim Good As Boolean
Barr = Split(BigString, ",")
Larr = Split(LittleString, ",")
For Each B In Barr
Good = True
For Each L In Larr
If L = B Then Good = False
Next
If Good Then unikue = unikue & "," & B
Next B
If unikue <> "" Then unikue = Mid(unikue, 2)
End Function

Answer 3

Couple of things with this code
the variable Target() - You never tell code how big this array is or if you want to make it bigger - my full code below will grow for each match that is found
Source(x, y).Value - You dont need to use Value for arrays. you also do not need x and y as you are only reading in one column you only need source(x)
Where I have wrote MISSING in the full code - these lines where missing and would have caused you issues.
The purpose of Found is that for every time source(x) is found in Comparison(y) then Found is incremented. If it has never been incremented then we can assume that it is to be captured in target.
One other note is that you do not specify where you want to output Target to. so currently the target array does not go anywhere
Sub compare()
Dim cont As Long
Dim x As Long
Dim y As Long
Dim Source As Variant
Dim Comparison As Variant
Dim Target() As Variant
ReDim Target(1)
With ThisWorkbook.Worksheets("Open items")
For cont = 1 To .Cells(.Rows.Count, 4).End(xlUp).Row
Source = Split(.Range("D" & cont).Value, ",")
Comparison = Split(.Range("O" & cont).Value, ",")
For x = LBound(Source) To UBound(Source)
Found = 0
For y = LBound(Comparison) To UBound(Comparison)
If Source(x) = Comparison(y) Then
Found = Found + 1
'count if found
End If 'MISSING
Next
'if values are found dont add to target
If Found = 0 Then
Target(UBound(Target)) = Source(x)
ReDim Preserve Target(UBound(Target) + 1)
End If
Next
Next cont
End With 'MISSING
End Sub