How to “flatten” or “collapse” a 2D Excel table into 1D?

Question

I have a two dimensional table with countries and years in Excel. eg.

        1961        1962        1963        1964
USA      a           x            g           


        

Answer 1

I developed another macro because I needed to refresh the output table quite often (input table was filled by other) and I wanted to have more info in my output table (more copied column and some formulas)

Sub TableConvert()

Dim tbl As ListObject 
Dim t
Rows As Long
Dim tCols As Long
Dim userCalculateSetting As XlCalculation
Dim wrksht_in As Worksheet
Dim wrksht_out As Worksheet

'##block calculate and screen refresh
Application.ScreenUpdating = False
userCalculateSetting = Application.Calculation
Application.Calculation = xlCalculationManual

'## get the input and output worksheet
Set wrksht_in = ActiveWorkbook.Worksheets("ressource_entry")'## input
Set wrksht_out = ActiveWorkbook.Worksheets("data")'## output.


'## get the table object from the worksheet
Set tbl = wrksht_in.ListObjects("Table14")  '## input
Set tb2 = wrksht_out.ListObjects("Table2") '## output.

'## delete output table data
If Not tb2.DataBodyRange Is Nothing Then
    tb2.DataBodyRange.Delete
End If

'## count the row and col of input table

With tbl.DataBodyRange
     tRows = .Rows.Count
     tCols = .Columns.Count
End With

'## check every case of the input table (only the data part)
For j = 2 To tRows '## parse all row from row 2 (header are not checked)
    For i = 5 To tCols '## parse all column from col 5 (first col will be copied in each record)
        If IsEmpty(tbl.Range.Cells(j, i).Value) = False Then
            '## if there is time enetered create a new row in table2 by using the first colmn of the selected cell row and cell header plus some formula
            Set oNewRow = tb2.ListRows.Add(AlwaysInsert:=True)
            oNewRow.Range.Cells(1, 1).Value = tbl.Range.Cells(j, 1).Value
            oNewRow.Range.Cells(1, 2).Value = tbl.Range.Cells(j, 2).Value
            oNewRow.Range.Cells(1, 3).Value = tbl.Range.Cells(j, 3).Value
            oNewRow.Range.Cells(1, 4).Value = tbl.Range.Cells(1, i).Value
            oNewRow.Range.Cells(1, 5).Value = tbl.Range.Cells(j, i).Value
            oNewRow.Range.Cells(1, 6).Formula = "=WEEKNUM([@Date])"
            oNewRow.Range.Cells(1, 7).Formula = "=YEAR([@Date])"
            oNewRow.Range.Cells(1, 8).Formula = "=MONTH([@Date])"
        End If
   Next i
Next j
ThisWorkbook.RefreshAll

'##unblock calculate and screen refresh
Application.ScreenUpdating = True 
Application.Calculate
Application.Calculation = userCalculateSetting

End Sub

Answer 2

updated ReversePivotTable function so i can specify number of header columns and rows

Sub ReversePivotTable()
'   Before running this, make sure you have a summary table with column headers.
'   The output table will have three columns.
    Dim SummaryTable As Range, OutputRange As Range
    Dim OutRow As Long
    Dim r As Long, c As Long

    Dim lngHeaderColumns As Long, lngHeaderRows As Long, lngHeaderLoop As Long

    On Error Resume Next
    Set SummaryTable = ActiveCell.CurrentRegion
    If SummaryTable.Count = 1 Or SummaryTable.Rows.Count < 3 Then
        MsgBox "Select a cell within the summary table.", vbCritical
        Exit Sub
    End If
    SummaryTable.Select

    Set OutputRange = Application.InputBox(prompt:="Select a cell for the 3-column output", Type:=8)
    lngHeaderColumns = Application.InputBox(prompt:="Header Columns")
    lngHeaderRows = Application.InputBox(prompt:="Header Rows")
'   Convert the range
    OutRow = 2
    Application.ScreenUpdating = False
    'OutputRange.Range("A1:D3") = Array("Column1", "Column2", "Column3", "Column4")
    For r = lngHeaderRows + 1 To SummaryTable.Rows.Count
        For c = lngHeaderColumns + 1 To SummaryTable.Columns.Count
            ' loop through all header columns and add to output
            For lngHeaderLoop = 1 To lngHeaderColumns
                OutputRange.Cells(OutRow, lngHeaderLoop) = SummaryTable.Cells(r, lngHeaderLoop)
            Next lngHeaderLoop
            ' loop through all header rows and add to output
            For lngHeaderLoop = 1 To lngHeaderRows
                OutputRange.Cells(OutRow, lngHeaderColumns + lngHeaderLoop) = SummaryTable.Cells(lngHeaderLoop, c)
            Next lngHeaderLoop

            OutputRange.Cells(OutRow, lngHeaderColumns + lngHeaderRows + 1) = SummaryTable.Cells(r, c)
            OutputRange.Cells(OutRow, lngHeaderColumns + lngHeaderRows + 1).NumberFormat = SummaryTable.Cells(r, c).NumberFormat
            OutRow = OutRow + 1
        Next c
    Next r
End Sub

Answer 3

@Adam Davis's answer is perfect, but just in case you're as clueless as I am about Excel VBA, here's what I did to get the code working in Excel 2007:

1. Open the workbook with the Matrix that needs to be flattened to a table and navigate to that worksheet
2. Press Alt-F11 to open the VBA code editor.
3. On the left pane, in the Project box, you'll see a tree structure representing the excel objects and any code (called modules) that already exist. Right click anywhere in the box and select "Insert->Module" to create a blank module file.
4. Copy and paste @Adman Davis's code from above as is into the blank page the opens and save it.
5. Close the VBA editor window and return to the spreadsheet.
6. Click on any cell in the matrix to indicate the matrix you'll be working with.
7. Now you need to run the macro. Where this option is will vary based on your version of Excel. As I'm using 2007, I can tell you that it keeps its macros in the "View" ribbon as the farthest right control. Click it and you'll see a laundry list of macros, just double click on the one called "ReversePivotTable" to run it.
8. It will then show a popup asking you to tell it where to create the flattened table. Just point it to any empty space an your spreadsheet and click "ok"

You're done! The first column will be the rows, the second column will be the columns, the third column will be the data.