Sum Column B based on Column A using Excel VBA Macro

Question

OK, I have a simple problem that I need help with in a VBA Macro. I have an excel sheet that looks like this...

Product #     Count
101              1
102          


        

Answer 1

I know it' late... but I've been brought here by Sum up column B based on colum C values and so I post a solution with the same "formula" approach I used there but adapted to this actual need

Option Explicit

Sub main()

    With ActiveSheet
        With .Range("A:B").Resize(.cells(.Rows.Count, 1).End(xlUp).row) '<== here adjust "A:B" to whatever colums range you need
            With .Offset(1).Resize(.Rows.Count - 1)
                .Offset(, .Columns.Count).Resize(, 1).FormulaR1C1 = "=SUMIF(C1,RC1,C2)" ' "helper" column: it's the 1st column right of data columns (since ".Offset(, .Columns.Count)")
                .Columns(2).Value = .Offset(, .Columns.Count).Resize(, 1).Value 'update "count" with sum-up from "helper" column

                With .Offset(, .Columns.Count).Resize(, 1) ' reference to "helper" column
                    .FormulaR1C1 = "=IF(countIF(R1C1:RC1,RC1)=1,1,"""")" ' locate Product# repetition with blank cells
                    .Value = .Value 'fix values
                    .SpecialCells(xlCellTypeBlanks).EntireRow.Delete 'delete rows corresponding to blank cells
                    .ClearContents ' clear "helper" column
                End With
            End With
        End With
    End With

    End Sub

it makes use of a "helper" columns, which I assumed could be the one adjacent to the last data columns (i.e.: if data columns are "A:B" then helper column is "C")

should different "helper" column be needed then see comments about how it's located and change code accordingly

Answer 2

Based the code in Sub doIt(), is possible in the for Each ycle to retrive also the number of occurence?

Example:

Product # 101 have 4 occurence

Product # 102 have 2 occurence ecc...

Answer 3

Assuming the data is in columns A and B, you can do it with a formula:

=SUMIF(A:A,101,B:B)

Or if you put 101 in C1:

=SUMIF(A:A,C1,B:B)

EDIT

However if you still require VBA, here is my (quick and dirty) proposal - I use a dictionary to keep track of the sum for each item.

Sub doIt()

  Dim data As Variant
  Dim i As Long
  Dim countDict As Variant
  Dim category As Variant
  Dim value As Variant

  Set countDict = CreateObject("Scripting.Dictionary")

  data = ActiveSheet.UsedRange 'Assumes data is in columns A/B

  'Populate the dictionary: key = category / Item = count
  For i = LBound(data, 1) To UBound(data, 1)
    category = data(i, 1)
    value = data(i, 2)
    If countDict.exists(category) Then
      countDict(category) = countDict(category) + value 'if we have already seen that category, add to the total
    Else
      countDict(category) = value 'first time we find that category, create it
    End If
  Next i

  'Copy dictionary into an array
  ReDim data(1 To countDict.Count, 1 To 2) As Variant

  Dim d As Variant
  i = 1
  For Each d In countDict
    data(i, 1) = d
    data(i, 2) = countDict(d)
    i = i + 1
  Next d

  'Puts the result back in the sheet in column D/E, including headers
  With ActiveSheet
    .Range("D1").Resize(UBound(data, 1), UBound(data, 2)) = data
  End With

End Sub

Answer 4

The easiest thing is to use a Pivot Table in this case as Tim suggested.

Answer 5

Here is a VBA solution that uses multidimensional arrays. I noticed you said you are a bit new to VBA so I tried to put some meaningful comments in there. One thing that might look strange is when I redimension the arrays. That's because when you have multidimensional arrays you can only ReDim the last dimension in the array when you use the Preserve keyword.

Here is how my data looked:

Product Count
101     1
102     1
101     2
102     2
107     7
101     4
101     4
189     9

And here is the code. It has the same output as my last answer. Test this in a new workbook and put the test data in Sheet1 with headers.

Option Explicit

Sub testFunction()
    Dim rng As Excel.Range
    Dim arrProducts() As String
    Dim i As Long

    Set rng = Sheet1.Range("A2:A9")

    arrProducts = getSumOfCountArray(rng)

    Sheet2.Range("A1:B1").Value = Array("Product", "Sum of Count")

    ' go through array and output to Sheet2
    For i = 0 To UBound(arrProducts, 2)
        Sheet2.Cells(i + 2, "A").Value = arrProducts(0, i)
        Sheet2.Cells(i + 2, "B").Value = arrProducts(1, i)
    Next

End Sub

' Pass in the range of the products
Function getSumOfCountArray(ByRef rngProduct As Excel.Range) As String()
    Dim arrProducts() As String
    Dim i As Long, j As Long
    Dim index As Long

    ReDim arrProducts(1, 0)

    For j = 1 To rngProduct.Rows.Count
        index = getProductIndex(arrProducts, rngProduct.Cells(j, 1).Value)
        If (index = -1) Then
            ' create value in array
            ReDim Preserve arrProducts(1, i)
            arrProducts(0, i) = rngProduct.Cells(j, 1).Value ' product name
            arrProducts(1, i) = rngProduct.Cells(j, 2).Value ' count value
            i = i + 1
        Else
            ' value found, add to id
            arrProducts(1, index) = arrProducts(1, index) + rngProduct.Cells(j, 2).Value
        End If
    Next

    getSumOfCountArray = arrProducts
End Function

Function getProductIndex(ByRef arrProducts() As String, ByRef strSearch As String) As Long
    ' returns the index of the array if found
    Dim i As Long
    For i = 0 To UBound(arrProducts, 2)
        If (arrProducts(0, i) = strSearch) Then
            getProductIndex = i
            Exit Function
        End If
    Next

    ' not found
    getProductIndex = -1
End Function

Answer 6

Sub BestWaytoDoIt()

Dim i As Long                    ' Loop Counter
Dim int_DestRwCntr As Integer    ' Dest. sheet Counter
Dim dic_UniquePrd As Scripting.Dictionary
Set dic_UniquePrd = New Scripting.Dictionary

For i = 2 To Sheet1.Range("A" & Sheet1.Cells.Rows.Count - 1).End(xlUp).Row
    If dic_UniquePrd.exist(Sheet1.Range("A" & i).Value) <> True Then
        dic_UniquePrd.Add Sheet1.Range("A" & i).Value, DestRwCntr
        sheet2.Range("A" & int_DestRwCntr).Value = Sheet1.Range("A" & i).Value
        sheet2.Range("B" & int_DestRwCntr).Value = Sheet1.Range("B" & i).Value
    Else
        sheet2.Range("A" & dic_UniquePrd.Item(Sheet1.Range("A" & i).Value)).Value = sheet2.Range("B" & dic_UniquePrd.Item(Sheet1.Range("A" & i).Value)).Value + Sheet1.Range("B" & i).Value
    End If
Next
End Sub

This will serve the purpose.. Only thing to remember is to activate "Microsoft Scripting Runtimes" in references.