Separating Evens and Odds

Dimitris has a series of integer values in column A. He would like a way to show the odd values in column B and the even values in column C. He wants the values to be in contiguous cells, with no spaces, and to also be in ascending order. Dimitris wonders if he would need a macro to process his data in this way.

The short answer is that you can, indeed, do this without resorting to a macro. However, if you need to perform this type of processing a lot, you may find it more beneficial to actually use a macro.

First, let's look at the non-macro approaches. You could, if desired, write simple formulas in columns B and C that simply check if the value in column A is odd or even and, if it is appropriate to the column, copy the value over. For instance, you could have the following in column B:

=IF(ISODD(A1),A1,"")

In column C, all you would need to do is replace ISODD with ISEVEN. When you copy these formulas down, then colum B contains only odd values and column C contains only even values. The problem, of course, is that the result doesn't match what Dimitris is looking for: He wants the values in contiguous cells (no blanks) and he wants them in ascending order.

Granted, you can take additional steps to get the desired results—for instance, you could copy the results in columns B and C and paste back values (so the formulas are removed) and then sort the results. This adds additional steps to your work.

There is a way to get a much "cleaner" result by simply using an array formula. Let's assume you're your values are in cells A1:A100. With cells B1:B100 selected, enter the following in the Formula Bar:

=IFERROR(SMALL(IFERROR(INDEX($A$1:$A$100,SMALL(
IF(MOD($A$1:$A$100,2)=1,ROW($A$1:$A$100)),ROW(
$A1:$A$100))),""),ROW()),"")

Remember that this is all a single formula. Since it is designed to be an array formula, terminate it by entereing Ctrl+Shift+Enter. The result is that you have the odd values in column B, in contiguous cells, in ascending order. To get the even values into column C, first copy B1:B100 to C1:C100. Then, select the range C1:C100. Press F2 to enter edit mode and change the "=1" in the middle of the formula to "=0". Again, terminate the formula by pressing Ctrl+Shift+Enter.

You should note that this formula won't work properly if there are any blanks in the A1:A100 range or if there are any text values in the range. The reason that blanks won't work is because they are treated as a 0 formulaicly, and a 0 is considered even, thus showing up in column C. An alternative formula to determine odd values (column B) is to use the following array formula in cell B1:

=IFERROR(SMALL(IF(MOD($A$1:$A$100,2)>0,$A$1:
$A$100,"x"),ROW()),"")

To deal with the potential "blank cell" issue, you could then use the following array formula in cell C1:

=IFERROR(SMALL(IF((MOD($A$1:$A$100,2)=0)*NOT(
ISBLANK($A$1:$A$100)),$A$1:$A$100,"x"),ROW()),"")

Copy B1:C1 down as many cells as necessary to get your results.

Earlier I mentioned that you may find it more beneficial to use a macro to process your values. The reason is simple—you can easily get rid of duplicate values (if you need to) and you can ignore blanks and text values. There are any number of ways that such a macro could be developed; I chose an approach that requires you to select which cells you want to process, clears the two columns to the right of those cells, and then puts odds and evens in those columns.

Sub OddsEvens()
    Dim rSource As Range
    Dim c As Range
    Dim sTemp As String
    Dim iVal As Integer
    Dim bGo As Boolean
    Dim sCols As String
    Dim vMsg As Variant
    Dim lOddCol As Long
    Dim iOddPtr As Integer
    Dim lEvenCol As Long
    Dim iEvenPtr As Integer
    Dim iOdds(999) As Integer
    Dim iEvens(999) As Integer
    Dim J As Integer

    Set rSource = Selection
    If rSource.Columns.Count = 1 Then
        lOddCol = rSource.Column + 1
        lEvenCol = rSource.Column + 2
        sCols = Chr(lOddCol + 64) & ":"
        sCols = sCols & Chr(lEvenCol + 64)

        sTemp = "The contents of columns " & sCols
        sTemp = sTemp & " will be deleted. Ok to proceed?"
        vMsg = MsgBox(sTemp, vbYesNo, "Odds and Evens")
        If vMsg = vbYes Then
            Application.ScreenUpdating = False
            Range(sCols).Clear
            iOddPtr = 0
            iEvenPtr = 0
            For Each c In rSource
                bGo = True
                ' Is the cell empty?
                If IsEmpty(c.Value) Then bGo = False
                ' Does the cell contain non-numeric value?
                If Not IsNumeric(c.Value) Then bGo = False
                If bGo Then
                    iVal = c.Value
                    If Int(iVal / 2) * 2 = iVal Then
                        ' Even number
                        ' Check to see if duplicate
                        For J = 1 To iEvenPtr
                            If iEvens(J) = iVal Then bGo = False
                        Next J
                        If bGo Then
                            iEvenPtr = iEvenPtr + 1
                            iEvens(iEvenPtr) = iVal
                        End If
                    Else
                        'Odd number
                        ' Check to see if duplicate
                        For J = 1 To iOddPtr
                            If iOdds(J) = iVal Then bGo = False
                        Next J
                        If bGo Then
                            iOddPtr = iOddPtr + 1
                            iOdds(iOddPtr) = iVal
                        End If
                    End If
                End If
            Next c

            ' Stuff values into proper columns
            For J = 1 To iOddPtr
                Cells(rSource.Row + J - 1, lOddCol) = iOdds(J)
            Next J
            For J = 1 To iEvenPtr
                Cells(rSource.Row + J - 1, lEvenCol) = iEvens(J)
            Next J

            ' Sort values in Odd column
            sTemp = Chr(lOddCol + 64) & rSource.Row & ":"
            sTemp = sTemp & Chr(lOddCol + 64) & rSource.Row _
              + iOddPtr - 1
            Range(sTemp).Select
            Selection.Sort key1:=Range(Chr(lOddCol + 64) _
              & rSource.Row), Order1:=xlAscending

            ' Sort values in Even column
            sTemp = Chr(lEvenCol + 64) & rSource.Row & ":"
            sTemp = sTemp & Chr(lEvenCol + 64) & rSource.Row _
              + iEvenPtr - 1
            Range(sTemp).Select
            Selection.Sort key1:=Range(Chr(lEvenCol + 64) _
              & rSource.Row), Order1:=xlAscending

            rSource.Select
            Application.ScreenUpdating = True
        End If
    End If
End Sub

The macro does its work by stuffing values from the selected cells into either of two arrays (iEvens and iOdds). This is done so that the macro can easily check for duplicates in the values. Only if the cell is not empty, it contains a number, and that number is not a duplicate will the value be added to the appropriate array. The values are then stuffed back into the two columns and those values are sorted.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (6767) applies to Microsoft Excel 2007, 2010, 2013, 2016, 2019, 2021, and Excel in Microsoft 365.