Deleting Duplicate Visible Rows - vba

Question

I am trying to use the following VBA code to do two things.
Count the number of unique visible rows in a filtered worksheet.
Delete the duplicate rows
So far:
Function UniqueVisible(MyRange As Range) As Integer
Dim ws As Worksheet
Set ws = Worksheets(1)
Dim R As Range
Dim V() As String
ReDim V(0 To MyRange.Count) As String
For Each R In MyRange
If (R.EntireRow.Hidden = False) Then
For Index = 0 To UniqueVisible
If (V(Index) = R.Value) Then
R.Delete
Exit For
End If
If (Index = UniqueVisible) Then
V(UniqueVisible) = R.Value
UniqueVisible = UniqueVisible + 1
End If
Next
End If
Next R
End Function
This counts okay, and if I replace R.Delete with MsgBox(R.Row) I get the correct row number of the duplicate.
R.Delete does nothing.
R.EntireRow.Delete does nothing
ws.Rows(R.Row).Delete does nothing.
UPDATE
This doesn't seem to be working
Function UniqueVisible(MyRange As Range) As Integer
Dim ws As Worksheet
Set ws = Worksheets(1)
Dim R As Range
Dim Dup As Integer
Dup = 0
Dim Dups() As Integer
ReDim Dups(0 To MyRange.Count) As Integer
Dim V() As String
ReDim V(0 To MyRange.Count) As String
For Each R In MyRange
If (R.EntireRow.Hidden = False) Then
For Index = 0 To UniqueVisible
If (V(Index) = R.Value) Then
Dups(Dup) = R.Row
Dup = Dup + 1
Exit For
End If
If (Index = UniqueVisible) Then
V(UniqueVisible) = R.Value
UniqueVisible = UniqueVisible + 1
End If
Next
End If
Next R
For Each D In Dups
ws.Rows(D).Delete
Next D
End Function

Answer 1

It seems you're breaking a few rules here.
You cannot use a function to delete rows in VBA. It does not matter whether you are using the function as a User Defined Function (aka UDF) on the worksheet or calling it from a sub in a VBA project. A function is meant to return a value, not perform operations that modify the structure (or even the values other than its own cell) on a worksheet. In your case, it could return an array of row numbers to be deleted by a sub.
It is considered canonical practise to start from the bottom (or the right for columns) and work up when deleting rows. Working from the top to the bottom may skip rows when a row is deleted and you loop to the next one.
Here is an example where a sub calls the function to gather the count of the unique, visible entries and an array of rows to be removed.
Sub remove_rows()
Dim v As Long, vDelete_These As Variant, iUnique As Long
Dim ws As Worksheet
Set ws = Worksheets(1)
vDelete_These = UniqueVisible(ws.Range("A1:A20"))
iUnique = vDelete_These(LBound(vDelete_These))
For v = UBound(vDelete_These) To (LBound(vDelete_These) + 1) Step -1 'not that we are working from the bottom up
ws.Rows(vDelete_These(v)).EntireRow.Delete
Next v
Debug.Print "There were " & iUnique & " unique, visible values."
End Sub
Function UniqueVisible(MyRange As Range)
Dim R As Range
Dim uniq As Long
Dim Dups As Variant
Dim v As String
ReDim Dups(1 To 1) 'make room for the unique count
v = ChrW(8203) 'seed out string hash check with the delimiter
For Each R In MyRange
If Not R.EntireRow.Hidden Then
If CBool(InStr(1, v, ChrW(8203) & R.Value & ChrW(8203), vbTextCompare)) Then
ReDim Preserve Dups(1 To UBound(Dups) + 1)
Dups(UBound(Dups)) = R.Row
Else
uniq = uniq + 1
v = v & R.Value & ChrW(8203)
End If
End If
Next R
Dups(LBound(Dups)) = uniq 'stuff the unique count into the primary of the array
UniqueVisible = Dups
End Function
Now, that is probably not how I would go about it. Seems easier to just write the whole thing into a single sub. However, understanding processes and limitations is important so I hope you can work with this.
Note that this does not have any error control. This should be present when dealing with arrays and deleting row in loops.

Answer 2

You can't delete a row while you're looping through the rows. You'll need to store the rows that need to be deleted in an array, and then loop through the array and delete the rows after it's done looping through the rows.