How to populate unique values into combobox? - excel

Question

I want to populate unique values into combobox.
My sheet details
Code:
Private Sub ComboBoxscname_DropButtonClick()
With Worksheets("A1")
ComboBoxscname.List = .Range("B2:B" & .Cells(.Rows.Count, "A").End(xlUp).Row).Value
End With
End Sub
I have highlighted with yellow which are duplicated for column "B" and should be displayed only once in combobox.
Another solution I have but getting error when selecting specific sheet name.
Sub ComboBoxscnameList()
Dim LR As Long
Dim ctrl As Object
'Set ctrl = Sheets("A1").Select
LR = Cells(Rows.Count, "B").End(xlUp).Row
ctrl.List() = CreateArray(Range("B2:B" & LR))
End Sub
'creates an array from a given range
'ignores blanks and duplicates
Function CreateArray(r As Range)
Dim col As New Collection, c As Range, TempArray(), i As Long
'for each cell in range r
For Each c In r
On Error Resume Next
col.Add c.Value, CStr(c.Value)
If Err.Number = 0 And Trim(c) <> "" Then
ReDim Preserve TempArray(i)
TempArray(i) = c.Value
i = i + 1
End If
Err.Clear
Next
CreateArray = TempArray
Erase TempArray
End Function
Private Sub ComboBoxscname_DropButtonClick()
Call ComboBoxscnameList
End Sub

Answer 1

The easiest way to save a unique set of values from a Column or Range is by using a Dictionary. You loop though your cells in column B, and check if each one is already in the Dictionary keys, the syntax is Dict.Exists("your_parameters").
You can read more about using Dictionary HERE.
Review the modified code below, you want to add it to your UserForm_Initialize() event.
Modified Code
Private Sub UserForm_Initialize()
Dim i As Long, ArrIndex As Long, LastRow As Long
Dim Dict As Object, Key As Variant
Dim HSNArr() As String
Application.ScreenUpdating = False
' us a Dictionary, and save unique Eco-System as array
Set Dict = CreateObject("Scripting.Dictionary")
With ThisWorkbook.Worksheets("Sheet2") ' <-- modify to your sheet's name
LastRow = .Cells(.Rows.Count, "B").End(xlUp).Row
ReDim HSNArr(1 To LastRow) ' redim HSN array >> will optimize size later
ArrIndex = 1
For i = 2 To LastRow
If Not Dict.Exists(.Range("B" & i).Value2) And Trim(.Range("B" & i).Value2) <> "" Then ' make sure not in Dictionary and ignore empty cells
Dict.Add .Range("B" & i).Value2, .Range("B" & i).Value2 ' add current HSN
HSNArr(ArrIndex) = .Range("B" & i).Value2
ArrIndex = ArrIndex + 1
End If
Next i
End With
ReDim Preserve HSNArr(1 To ArrIndex - 1) ' resize to populated size of Array
Application.ScreenUpdating = True
With Me.ComboBoxscname
.Clear ' clear previous combo-box contents
For i = 1 To UBound(HSNArr) ' loop through array, add each unique HSN to Combo-Box
.AddItem HSNArr(i)
Next i
' show default value
.Value = HSNArr(1)
End With
End Sub