baha-kev baha-kev - 4 months ago 40
R Question

melt / reshape in excel using VBA?

I'm currently adjusting to a new job where most of the work I share with colleagues is via MS Excel. I am using pivot tables frequently, and therefore need "stacked" data, precisely the output of the

melt()
function in the
reshape
(reshape2) package in R that I've come to rely on for this.

Could anyone get me started on a VBA macro to accomplish this, or does one exist already?

The outline of the macro would be:


  1. Select a range of cells in an Excel workbook.

  2. Start "melt" macro.

  3. Macro would create a prompt, "Enter number of id columns", where you would enter the number preceding columns of identifying information. (for the example R code below it's 4).

  4. Create a new worksheet in the excel file titled "melt"
    that would stack the data, and create a new column titled "variable"
    equal to the data column headers from the original selection.



In other words, the output would look exactly the same as the output of simply executing these two lines in R:

require(reshape)
melt(your.unstacked.dataframe, id.vars = 1:4)


Here's an example:

# unstacked data
> df1
Year Month Country Sport No_wins No_losses High_score Total_games
2 2010 5 USA Soccer 4 3 5 9
3 2010 6 USA Soccer 5 3 4 8
4 2010 5 CAN Soccer 2 9 7 11
5 2010 6 CAN Soccer 4 8 4 13
6 2009 5 USA Soccer 8 1 4 9
7 2009 6 USA Soccer 0 0 3 2
8 2009 5 CAN Soccer 2 0 6 3
9 2009 6 CAN Soccer 3 0 8 3

# stacking the data
> require(reshape)
> melt(df1, id.vars=1:4)

Year Month Country Sport variable value
1 2010 5 USA Soccer No_wins 4
2 2010 6 USA Soccer No_wins 5
3 2010 5 CAN Soccer No_wins 2
4 2010 6 CAN Soccer No_wins 4
5 2009 5 USA Soccer No_wins 8
6 2009 6 USA Soccer No_wins 0
7 2009 5 CAN Soccer No_wins 2
8 2009 6 CAN Soccer No_wins 3
9 2010 5 USA Soccer No_losses 3
10 2010 6 USA Soccer No_losses 3
11 2010 5 CAN Soccer No_losses 9
12 2010 6 CAN Soccer No_losses 8
13 2009 5 USA Soccer No_losses 1
14 2009 6 USA Soccer No_losses 0
15 2009 5 CAN Soccer No_losses 0
16 2009 6 CAN Soccer No_losses 0
17 2010 5 USA Soccer High_score 5
18 2010 6 USA Soccer High_score 4
19 2010 5 CAN Soccer High_score 7
20 2010 6 CAN Soccer High_score 4
21 2009 5 USA Soccer High_score 4
22 2009 6 USA Soccer High_score 3
23 2009 5 CAN Soccer High_score 6
24 2009 6 CAN Soccer High_score 8
25 2010 5 USA Soccer Total_games 9
26 2010 6 USA Soccer Total_games 8
27 2010 5 CAN Soccer Total_games 11
28 2010 6 CAN Soccer Total_games 13
29 2009 5 USA Soccer Total_games 9
30 2009 6 USA Soccer Total_games 2
31 2009 5 CAN Soccer Total_games 3
32 2009 6 CAN Soccer Total_games 3

Answer

I've got two posts, with usable code and downloadable workbook, on doing this in Excel/VBA on my blog:

http://yoursumbuddy.com/data-normalizer

http://yoursumbuddy.com/data-normalizer-the-sql/

Here's the code:

'Arguments
'List: The range to be normalized.
'RepeatingColsCount: The number of columns, starting with the leftmost,
'   whose headings remain the same.
'NormalizedColHeader: The column header for the rolled-up category.
'DataColHeader: The column header for the normalized data.
'NewWorkbook: Put the sheet with the data in a new workbook?
'
'NOTE: The data must be in a contiguous range and the
'rows that will be repeated must be to the left,
'with the rows to be normalized to the right.

Sub NormalizeList(List As Excel.Range, RepeatingColsCount As Long, _
    NormalizedColHeader As String, DataColHeader As String, _
    Optional NewWorkbook As Boolean = False)

Dim FirstNormalizingCol As Long, NormalizingColsCount As Long
Dim ColsToRepeat As Excel.Range, ColsToNormalize As Excel.Range
Dim NormalizedRowsCount As Long
Dim RepeatingList() As String
Dim NormalizedList() As Variant
Dim ListIndex As Long, i As Long, j As Long
Dim wbSource As Excel.Workbook, wbTarget As Excel.Workbook
Dim wsTarget As Excel.Worksheet

With List
    'If the normalized list won't fit, you must quit.
   If .Rows.Count * (.Columns.Count - RepeatingColsCount) > .Parent.Rows.Count Then
        MsgBox "The normalized list will be too many rows.", _
               vbExclamation + vbOKOnly, "Sorry"
        Exit Sub
    End If

    'You have the range to be normalized and the count of leftmost rows to be repeated.
   'This section uses those arguments to set the two ranges to parse
   'and the two corresponding arrays to fill
   FirstNormalizingCol = RepeatingColsCount + 1
    NormalizingColsCount = .Columns.Count - RepeatingColsCount
    Set ColsToRepeat = .Cells(1).Resize(.Rows.Count, RepeatingColsCount)
    Set ColsToNormalize = .Cells(1, FirstNormalizingCol).Resize(.Rows.Count, NormalizingColsCount)
    NormalizedRowsCount = ColsToNormalize.Columns.Count * .Rows.Count
    ReDim RepeatingList(1 To NormalizedRowsCount, 1 To RepeatingColsCount)
    ReDim NormalizedList(1 To NormalizedRowsCount, 1 To 2)
End With

'Fill in every i elements of the repeating array with the repeating row labels.
For i = 1 To NormalizedRowsCount Step NormalizingColsCount
    ListIndex = ListIndex + 1
    For j = 1 To RepeatingColsCount
        RepeatingList(i, j) = List.Cells(ListIndex, j).Value2
    Next j
Next i

'We stepped over most rows above, so fill in other repeating array elements.
For i = 1 To NormalizedRowsCount
    For j = 1 To RepeatingColsCount
        If RepeatingList(i, j) = "" Then
            RepeatingList(i, j) = RepeatingList(i - 1, j)
        End If
    Next j
Next i

'Fill in each element of the first dimension of the normalizing array
'with the former column header (which is now another row label) and the data.
With ColsToNormalize
    For i = 1 To .Rows.Count
        For j = 1 To .Columns.Count
            NormalizedList(((i - 1) * NormalizingColsCount) + j, 1) = .Cells(1, j)
            NormalizedList(((i - 1) * NormalizingColsCount) + j, 2) = .Cells(i, j)
        Next j
    Next i
End With

'Put the normal data in the same workbook, or a new one.
If NewWorkbook Then
    Set wbTarget = Workbooks.Add
    Set wsTarget = wbTarget.Worksheets(1)
Else
    Set wbSource = List.Parent.Parent
    With wbSource.Worksheets
        Set wsTarget = .Add(after:=.Item(.Count))
    End With
End If

With wsTarget
    'Put the data from the two arrays in the new worksheet.
   .Range("A1").Resize(NormalizedRowsCount, RepeatingColsCount) = RepeatingList
    .Cells(1, FirstNormalizingCol).Resize(NormalizedRowsCount, 2) = NormalizedList

    'At this point there will be repeated header rows, so delete all but one.
   .Range("1:" & NormalizingColsCount - 1).EntireRow.Delete

    'Add the headers for the new label column and the data column.
   .Cells(1, FirstNormalizingCol).Value = NormalizedColHeader
    .Cells(1, FirstNormalizingCol + 1).Value = DataColHeader
End With
End Sub

You’d call it like this:

Sub TestIt()
NormalizeList ActiveSheet.UsedRange, 4, "Variable", "Value", False
End Sub
Comments