Averaging over a Non-Contiguous Named Range - excel

Question

I am trying to average non-contiguous cells as shown.
I am taking the average of columns A and C for each row. I am trying to do the same but with a named range (including columns A and C), because my actual data have thousands of columns and it will be hell to write the formula let alone for the users to understand what is being averaged.
Obviously, I don't understand how indexing a named range works. I expected that index(RangeAC,2) would give me the second row of values in RangeAC. Instead, I get the second row in column A. Trying index(RangeAC,2,2) results in an error.
Is it possible to get this average with a named range or do I need a different approach?

Answer 1

I don't know if I'm missing something, but isnt this as simple as using the Excel intersect operator?:
=AVERAGE(RangeAC 8:8)
Put in the first row of the named Range data(which seems to be 8:8 in your case), and copy down...
Isnt that the same as the suggested VBA UDF from MrExcel forums?

Answer 2

Option 1:
Lets say the name of your range is my_data like this one:
This is the formula to use:
Public Function calculate_avg(rng As Range) As Double
calculate_avg = WorksheetFunction.Average(Range(rng.Cells(1, 1).Address, Cells(rng.Rows.Count + rng.Cells(1, 1).Row - 1, rng.Columns.Count + rng.Cells(1, 1).Column - 1).Address))
End Function
Option 2:
Your named range is the following:
You want the average of the 2. and the 3. column. (C&D).
This is how you get it:
Option Explicit
Public Function calculate_avg(rng As Range, Optional l_starting_col As Long = 1, Optional l_end_col As Long = 1) As Double
Dim my_start As Range
Dim my_end As Range
Set my_start = Cells(rng.Cells(1, 1).Row, l_starting_col + rng.Cells(1, 1).Column - 1)
Set my_end = Cells(rng.Cells(rng.Rows.Count, l_end_col).Row, rng.Columns.Count - rng.Cells(1, l_end_col).Column + l_end_col)
'Debug.Print my_start.Address
'Debug.Print my_end.Address
calculate_avg = WorksheetFunction.Average(Range(my_start, my_end))
End Function
You pass as arguments the starting and the end column. Thus something like this:
?calculate_avg([my_test_big],2,3) in the immediate window returns 72,5. The same can be used as an Excel formula. Good luck! :)+
Option 3
Public Function calculate_avg_row(rng As Range, Optional l_row As Long = 1) As Double
Dim my_start As Range
Dim my_end As Range
Set my_start = Cells(rng.Cells(l_row, 1).Row, rng.Cells(l_row, 1).Column)
Set my_end = rng.Cells(l_row, rng.Columns.Count)
Debug.Print my_start.Address
Debug.Print my_end.Address
calculate_avg_row = WorksheetFunction.Average(Range(my_start, my_end))
End Function
This one works like this:
calculate_avg_row([test_rng],5)
And gives the average of the 5th row of the named range, including all columns of the named range.

Answer 3

Could you not attach a name to a formula as well? If so,go to the "Formula" tab , "Define Name"and type in the "Refers to" box =Average(A1,C1)). In the name box, you could name it "Average" or whatever you choose to call it.The references would continue to be non-contiguous if you dragged to the right or down the sheet. I am not sure if that is exactly what you're seeking.

Answer 4

I appreciate everyone's help. This problem has taken me considerably longer than I was willing to spend on it. Non-contiguous ranges are a nightmare in Excel.
Eric at Mr Excel proposed the most elegant working solution - just one line of VBA.

Answer 5

The third parameter of the Index function Reference form can be used to specify the area number:
= AVERAGE( INDEX(RangeAC, ROW()), INDEX(RangeAC, ROW(), , 2) )
or if RangeAC does not start at row 1, something like:
= AVERAGE( INDEX(RangeAC, ROW()-ROW(RangeAC)+1), INDEX(RangeAC, ROW()-ROW(RangeAC)+1, , 2) )