Determining Sorting Criteria

Suppose that a co-worker gives you have a worksheet that has several hundred rows of data in 27 columns. Before you start working with the data, you might want to know if it has previously been sorted. Knowing the information may not only remove the need to resort the data, but will also give you an idea as to what your co-worker felt was the most important way to look at the data.

Unfortunately, Excel doesn't have a built-in way to determine the sorting criteria used for a range of data. You could theoretically write a macro that would check each column and see if it were in ascending or descending order. This will tell you if that single column was sorted, but that doesn't necessarily mean that the entire data table was sorted by that column—it could just be coincidence that the column is in sorted order, and the sort was done by some other column. The task of checking gets even trickier when you start considering secondary and tertiary sorts.

There is one thing you can try, however, to determine if a particular column is sorted and whether it is sorted in ascending or descending order. (Remember: this won't tell you if the particular column was the primary column used for sorting, it will only tell you if the column is sorted.)

The idea behind the macro is to copy the contents of the column to a temporary worksheet, two times. For instance, if you want to check out column F, the macro copies column F to columns A and B on the temporary worksheet. The macro then sorts column B in ascending order and compares it to column A. If the sorted and unsorted columns are the same, then the original column was in ascending order. Then column B is sorted in descending order and the comparison done again. Again, if the columns are equal then the column is in descending order.

Sub TestIfSorted(i)
    Dim CColumn as Number
    Dim CSheet as String
    Dim FlagSort as String

    'Identify Current Column and Current Sheet
    CColumn = i
    CSheet = ActiveSheet.Name
    FlagSort = ""

    'Add a temporary sheet to test for sorting
    Sheets.Add
    ActiveSheet.Name = "TempSort"

    'Copy CURRENT column to Columns A,B in Current Sheet
    Sheets(CSheet).Select
    Columns(CColumn).Select
    Selection.Copy

    Sheets("TempSort").Select
    Range("A1").Select
    ActiveSheet.Paste
    Range("B1").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False

    'In Column C test for equality of Columns A/B
    'If Sum in C1=0 then OK otherwise Col A<>Col B
    Range("B2").Select
    Selection.End(xlDown).Select
    Bottom = ActiveCell.Row
    Range(Cells(2, 3), Cells(Bottom, 3)).Select
    Selection.FormulaArray = "=IF(RC[-2]=RC[-1],0,1)"
    Range("C1").Select
    ActiveCell.FormulaR1C1 = "=SUM(R[1]C:R[6535]C)"

    'Sort Column B--Ascending - See if c1=0
    Columns("B:B").Select
    Selection.Sort Key1:=Range("B2"), Order1:=xlDescending, _
      Header:=xlYes, OrderCustom:=1, MatchCase:=False, _
      Orientation:=xlTopToBottom, DataOption1:=xlSortNormal
    If Cells(1, 3).Value = 0 Then FlagSort = "Ascending"

    'Sort Column B--Descending - See if c1=0
    Columns("B:B").Select
    Selection.Sort Key1:=Range("B2"), Order1:=xlAscending, _
      Header:=xlYes, OrderCustom:=1, MatchCase:=False, _
      Orientation:=xlTopToBottom, DataOption1:=xlSortNormal
    If Cells(1, 3).Value = 0 Then FlagSort = "Descending"

    If FlagSort = "Ascending" Then
        'Color Header on original sheet yellow
        Sheets(CSheet).Cells(1, CColumn).Interior.ColorIndex = 36
    End If

    If FlagSort = "Descending" Then
        'Color Header on original sheet orange
        Sheets(CSheet).Cells(1, CColumn).Interior.ColorIndex = 44
    End If

    'Delete temporary sheet
    Sheets("TempSort").Select
    ActiveWindow.SelectedSheets.Delete
End Sub

Once it is determined whether the original column was in ascending or descending order, then the first cell of the column in the original worksheet is set to yellow or orange, respectively. Finally, the temporary worksheet is deleted.

This macro could be modified so that it was called once for each column in a data table. Running the macro for an entire table wouldn't take that long, but would provide a colorful representation as to whether individual columns are sorted in ascending or descending order.

Of course, any macro like this is not trivial, so it may just be easier for you to figure out how you want to sort the data, and then sort it that way from the get-go.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (2395) applies to Microsoft Excel 97, 2000, 2002, and 2003.