Aggregate, Collate and Transpose rows into columns

Question

I have the following table

 Id     Letter
1001    A
1001    H
1001    H
1001    H

1001    B
1001    H
1001    H
1001    H

1001    H
1001    H
1001    H

10         


        

Answer 1

For tasks like this Microsoft added "Get&Transform" to Excel 2016. In order to use this functionality in earlier versions, you have to use the Power Query Add-In. The M-code is very short:

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    FillIdDown = Table.FillDown(Source,{"Id"}),
    ReplaceNull = Table.ReplaceValue(FillIdDown,null," ",Replacer.ReplaceValue,{"Letter"}),
    Transform = Table.Group(ReplaceNull, {"Id"}, {{"Count", each Text.Combine(_[Letter])}})
in
    Transform

Your data should sit in "Table1". https://www.dropbox.com/s/bnvchofmpvd048v/SO_AggregateCollateAndTransposeColsIntoRows.xlsx?dl=0

Answer 2

You cannot concatenate a range of cells (aka Letters) using native worksheet functions without knowing the scope beforehand. As your collection of strings into groups has random numbers of elements, a VBA loop approach seems the best (if not the only) way to address the issue. The loop can make determinations along the way that a worksheet function is simply incapable of performing.

Tap Alt+F11 and when the Visual Basic Editor (aka VBE) opens, immediately use the pull-down menus to Insert ► Module (Alt+I,M). Paste one or both of the following into the new pane titled something like Book1 - Module1 (Code).

To concatenate the string groups delimited by a space:

Sub concatenate_and_transpose_to_delim_string()
    Dim rw As Long, lr As Long, pid As Long, str As String
    Dim bPutInColumns As Boolean

    With ActiveSheet
        lr = .Cells(Rows.Count, 1).End(xlUp).row
        .Cells(1, 4).Resize(1, 2) = Array("Id", "Letters")
        pid = .Cells(2, 1).Value
        For rw = 2 To lr
            If IsEmpty(.Cells(rw, 1)) Then
                str = str & Chr(32)
                If pid <> .Cells(rw + 1, 1).Value Then
                    .Cells(Rows.Count, 4).End(xlUp).Offset(1, 0) = pid
                    .Cells(Rows.Count, 4).End(xlUp).Offset(0, 1) = str
                End If
            ElseIf pid <> .Cells(rw, 1).Value Then
                pid = .Cells(rw, 1).Value
                str = .Cells(rw, 2).Value
            Else
                str = str & .Cells(rw, 2).Value
            End If
        Next rw
        .Cells(Rows.Count, 4).End(xlUp).Offset(1, 0) = pid
        .Cells(Rows.Count, 4).End(xlUp).Offset(0, 1) = str
    End With
End Sub

To split the string groups into columns:

Sub concatenate_and_transpose_into_columns()
    Dim rw As Long, lr As Long, nr As Long, pid As Long, str As String

    With ActiveSheet
        lr = .Cells(Rows.Count, 1).End(xlUp).row
        .Cells(1, 4).Resize(1, 2) = Array("Id", "Letters")
        For rw = 2 To lr
            If IsEmpty(.Cells(rw, 1)) Then
                .Cells(nr, Columns.Count).End(xlToLeft).Offset(0, 1) = str
                str = vbNullString
            ElseIf pid <> .Cells(rw, 1).Value Then
                pid = .Cells(rw, 1).Value
                nr = .Cells(Rows.Count, 4).End(xlUp).Offset(1, 0).row
                .Cells(nr, 4) = pid
                str = .Cells(rw, 2).Value
            Else
                str = str & .Cells(rw, 2).Value
            End If
        Next rw
        .Cells(nr, Columns.Count).End(xlToLeft).Offset(0, 1) = str
    End With
End Sub

Tap Alt+Q to return to your worksheet. With your sample data on the active worksheet starting with Id in A1, tap Alt+F8 to open the Macros dialog and Run the macro.

Results from concatenate_and_transpose_to_delim_string:

    

Results from concatenate_and_transpose_into_columns:

    

The results will be written into the cells starting at D2. Probably best if there was nothing important there beforehand that would be overwritten.

Addendum:

I original misinterpreted your request and split the string groups into separate columns. I've rectified that with a supplemental routine that more closely follows your description of requirements but kept both variations for others to reference.

Answer 3

This option incorporates arrays. From performance point of view, it is much faster to once read data in the worksheet to an array, do your procedures directly in VBE and write the results back to the worksheets as compared to doing procedures in the worksheet cell by cell.

Sub transposing()
Const sDestination As String = "D2"
Dim ar1() As Variant
Dim ar2() As Variant
Dim i As Long 'counter

ar1 = ActiveSheet.Range("A2:B" & ActiveSheet.UsedRange.Rows.Count).Value
ReDim ar2(1 To 1, 1 To 2)
ar2(1, 1) = ar1(1, 1): ar2(1, 2) = ar1(1, 2)
For i = 2 To UBound(ar1, 1)
    If ar1(i, 1) = ar2(UBound(ar2, 1), 1) Then
        ar2(UBound(ar2, 1), 2) = ar2(UBound(ar2, 1), 2) & ar1(i, 2)
    ElseIf ar1(i, 1) = vbNullString Then
        ar2(UBound(ar2, 1), 2) = ar2(UBound(ar2, 1), 2) & " "
    Else
        ar2 = Application.Transpose(ar2)
        ReDim Preserve ar2(1 To 2, 1 To UBound(ar2, 2) + 1)
        ar2 = Application.Transpose(ar2)
        ar2(UBound(ar2, 1), 1) = ar1(i, 1)
        ar2(UBound(ar2, 1), 2) = ar2(UBound(ar2, 1), 2) & ar1(i, 2)
    End If
Next
ActiveSheet.Range(sDestination).Resize(UBound(ar2, 1), UBound(ar2, 2)).Value = ar2

End Sub

The result will look like this:

The line Const sDestination As String = "D2" states the beginning of the output. Change it to whichever cell you want.