vba - Excel Macro - Rows to Comma Separated Cells (Preserve/Aggregate Column)

Question

Based on this Data:

    <- A (Category) ->   <- B (Items) -> 
1   Cat1                 a
2   Cat1                 b
3   Cat1                 c
4   Cat2                 d
5   Cat3                 e
6   Cat4                 f
7   Cat4                 g

I need this:

    <- A (Category) ->   <- B (Items) -> 
1   Cat1                 a,b, c
2   Cat2                 d
3   Cat3                 e
4   Cat4                 f, g

Answer 1

If you want to keep your original data and merely summarize the data somewhere else, you can use the following method.

Create a user-defined function in VB that is essentially just like CONCATENATE, but can be used in an array formula. This will allow you to stick an IF statement in for the range variable in the CONCATENATE function. Here's a quick version I threw together:

Private Function CCARRAY(rr As Variant, sep As String)
'rr is the range or array of values you want to concatenate.  sep is the delimiter.
Dim rra() As Variant
Dim out As String
Dim i As Integer

On Error GoTo EH
rra = rr

out = ""
i = 1

Do While i <= UBound(rra, 1)
    If rra(i, 1) <> False Then
        out = out & rra(i, 1) & sep
    End If
    i = i + 1
Loop
out = Left(out, Len(out) - Len(sep))

CCARRAY = out
Exit Function

EH:
rra = rr.Value
Resume Next

End Function

So you could use the following in this table to summarize Items:

{=CCARRAY(IF(A1:A7="Cat1",B1:B7),", ")}

Remember to press Ctrl+Shift+Enter when entering the formula.