How to loop through columns and calculate averages? - arrays

Question

data series
I want to find the average for each segment of ten values down a column. (See data series picture)
Continuously all the way to the bottom of the data set. The data set can vary in length, and the code has to be "generic" of sorts.
Based on other code segments I have tried to do this:
Sub tenthavg()
Dim currentIndex As Long
Dim myArray() As Variant
Dim rng As Range
ReDim myArray(1 To 10)
Range("b1", Range("b1").End(xlDown)).Select
Set myArray = Selection
currentIndex = 1
Do Until currentIndex + 1 > UBound(myArray)
ActiveSheet.Cells(currentIndex, "T") = AverageOfSubArray(myArray, currentIndex, 10)
currentIndex = currentIndex + 1
Loop
End Sub
'=================================================================
Function AverageOfSubArray(myArray As Variant, startIndex As Long, elementCount As Long) As Double
Dim runningTotal As Double
Dim i As Long
For i = startIndex To (startIndex + elementCount - 1)
runningTotal = runningTotal + val(myArray(i))
Next i
AverageOfSubArray = runningTotal / elementCount
End Function
Unfortunately I can't make it work. Am I approaching this the right way?
If so, what am I doing wrong?

Answer 1

IMHO it's not quite the successful approach ... instead of Selecting EndDown and other concepts borrowed from interactive working make use of VBA's own mechanisms.
A "generic" approch takes Range start address, batch size and offsets where to put the result as arguments ...
Sub AvgX(MyR As Range, S As Integer, ORow As Integer, OCol As Integer)
' MyR = start of range
' S = batch size
' OCol, ORow = Offsets to place result in relation to last batch value
Dim Idx As Integer, Jdx As Integer, RSum As Variant
Idx = 1
RSum = 0
Do
For Jdx = 1 To S
RSum = RSum + MyR(Idx, 1)
Idx = Idx + 1
If MyR(Idx, 1) = "" Then Exit Do
Next Jdx
MyR(Idx - 1, 1).Offset(ORow, OCol) = RSum / (Jdx - 1)
RSum = 0
Loop
End Sub
and is called by
Sub Test()
AvgX [C4], 10, 0, 1
End Sub
to give you this result ...

Answer 2

You can get your result in a simpler way:
Sub tenthavg()
Dim LastRow As Long
LastRow = ThisWorkbook.Sheets("Your Sheet Name").Columns(2).Find("*", SearchOrder:=xlByRows, LookIn:=xlValues, SearchDirection:=xlPrevious).Row
Dim myArray(1 To 10) As Double
If LastRow < 10 Then
MsgBox "There's not enough data!"
Else
On Error Resume Next
For x = 1 To LastRow - 9
For y = 1 To 10
myArray(y) = ThisWorkbook.Sheets("Your Sheet Name").Cells(y + x - 1, 2).Value
Next y
ThisWorkbook.Sheets("Your Sheet Name").Cells(x, 20).FormulaR1C1 = 0
ThisWorkbook.Sheets("Your Sheet Name").Cells(x, 20).FormulaR1C1 = Application.Average(myArray)
Next x
End If
End Sub
Please note: I'm assuming you're data starts at B1 and you want the output on column T.