Create an array from unique values from column - excel

Question

I found this code in this forumn. I want to copy this unique values into an array
Dim sheetName As String
sheetName = Application.InputBox("Enter Sheet Name")
Sheets(sheetName).Range("E:E").AdvancedFilter Action:=xlFilterCopy, _
CopyToRange:=Sheets(sheetName).Range("O:O"), unique:=True

Answer 1

If you want to cut out the range middleman, you can get the values directly into a 1-dimensional VBA array by using a dictionary to make sure that only unique values are grabbed:
Function UniqueVals(Col As Variant, Optional SheetName As String = "") As Variant
'Return a 1-based array of the unique values in column Col
Dim D As Variant, A As Variant, v As Variant
Dim i As Long, n As Long, k As Long
Dim ws As Worksheet
If Len(SheetName) = 0 Then
Set ws = ActiveSheet
Else
Set ws = Sheets(SheetName)
End If
n = ws.Cells(Rows.Count, Col).End(xlUp).Row
ReDim A(1 To n)
Set D = CreateObject("Scripting.Dictionary")
For i = 1 To n
v = ws.Cells(i, Col).Value
If Not D.Exists(v) Then
D.Add v, 0
k = k + 1
A(k) = k
End If
Next i
ReDim Preserve A(1 To k)
UniqueVals = A
End Function
For example, UniqueVals("E",sheetName) will return an array consisting of the unique values in column E of sheetName.

Answer 2

Here's another method using VBA's Collection object instead of a dictionary.
Sub Dural()
Dim sheetName As String
Dim V As Variant, COL As Collection
Dim I As Long
Dim vUniques() As Variant
sheetName = Application.InputBox("Enter Sheet Name")
'Copy all data into variant array
' This will execute significantly faster than reading directly
' from the Worksheet range
With Worksheets(sheetName)
V = .Range(.Cells(1, "E"), .Cells(.Rows.Count, "E").End(xlUp))
End With
'Collect unique values
'Use the key property of the collection object to
' ensure no duplicates are collected
' (Trying to assign the same key to two items fails with an error
' which we ignore)
Set COL = New Collection
On Error Resume Next
For I = 1 To UBound(V, 1)
COL.Add Item:=V(I, 1), Key:=CStr(V(I, 1))
Next I
On Error GoTo 0
'write collection to variant array
ReDim vUniques(1 To COL.Count)
For I = 1 To COL.Count
vUniques(I) = COL(I)
Next I
Stop
End Sub

Answer 3

Another version, also using a dictionary. It works for me, but I must admit that still don't know how it works (I'm a beginner). I found this code somewhere in Stackoverflow, but can't spot the place.
Dim dU1 As Object, cU1 As Variant, iU1 As Long, lrU As Long
Dim i As Integer
Private Sub Go_Click()
Set dU1 = CreateObject("Scripting.Dictionary")
lrU = Cells(Rows.Count, 1).End(xlUp).Row
cU1 = Range("E1:E" & lrU)
For iU1 = 1 To UBound(cU1, 1)
dU1(cU1(iU1, 1)) = 1
Next iU1
For i = 0 To dU1.Count - 1
MsgBox "dU1 has " & dU1.Count & " elements and key#" & i & " is " & dU1.Keys()(i)
Next
End Sub