calculating average based on condition - excel

Question

I am trying to put together a formula that gives me the average total for an order if the order contains a specific item in it, how can I compute that?
For example if the table looks like
Order# | Item | Total for Entire order
a Apple 50
a Juice 50
a Chicken 50
a Bread 50
b Bread 23
b fish 23
c Chicken 43
c Wine 43
c rice 43
I want get the avg total of all orders that contain Chicken in them at least once? but dont want to count the total of once order twice in my average calculation - Thanks for looking

Answer 1

If one has the new Dynamic Array formulas:
=AVERAGE(INDEX(UNIQUE(FILTER(A2:C10,B2:B10="Chicken")),,3))
If not:
=SUMPRODUCT(((B2:B10="Chicken")*(C2:C10))/(COUNTIFS(A2:A10,A2:A10,B2:B10,"Chicken")+(B2:B10<>"Chicken")))/SUMPRODUCT((B2:B10="Chicken")/(COUNTIFS(A2:A10,A2:A10,B2:B10,"Chicken")+(B2:B10<>"Chicken")))

Answer 2

If you're not opposed to using VBA this function will do what you want.
=Average_Orders_Subset(range, criteria)
I changed this from my original answer to improve the functionality and added comments so you can see what it's doing. With the function you can add as many orders as you like. I have also tested it and it will work if the order letters are changed to numbers i.e. a = 1, b= 2 ect... Hope this helps. Don't hesitate to ask if you have any questions.
If your data starts in cell A1 it works like this:
Example: =Average_Orders_Subset(A1:C13,"Chicken")
With this version you can average for Chicken, rice, bread, anything you want.
In case you don't know here's how to add the code to the workbook.
If you want I can send you a copy of a workbook with it already built in.
Option Explicit
' User Defined Function to Average totals for only orders that contain specific string
' Pass the range and string you are looking for to the function
' Note the criteria string is case senstive so "chicken" is not the same as "Chicken"
'
' Example: =Average_Orders_Subset(A1:C13,"Chicken")
'
Public Function Average_Orders_Subset(rng As Range, criteria As String) As Double
Dim ws As Worksheet
Dim arrData() As Variant
Dim arrOrder() As Variant
Dim i As Long
Dim j As Long
Dim cnt As Long
Dim sum As Double
Dim avg As Double
' The worksheet with data
Set ws = ThisWorkbook.ActiveSheet
' Counter and array to keep track of order letters
cnt = 0
ReDim arrOrder(cnt)
With ws
' Create an array with all the values
arrData = rng.Value2
' Iterate through the array looking for orders with the criteria e.g., "Chicken"
For i = 2 To UBound(arrData)
' If criteria is found
If arrData(i, 2) = criteria Then
If cnt > 0 Then
' If the array of order letters is less than 0
If arrData(i, 1) <> arrOrder(cnt - 1) Then
' Checking if the order letter is already in the array so orders with two Chicken
' or multipe of any criteria don't get double counted
' Add them to the order letter array
arrOrder(cnt) = arrData(i, 1)
cnt = cnt + 1
ReDim Preserve arrOrder(cnt)
End If
ElseIf cnt = 0 Then
' This is to add the first occurence of the critera to the order array
arrOrder(cnt) = arrData(i, 1)
cnt = cnt + 1
ReDim Preserve arrOrder(cnt)
End If
End If
Next i
' Remove the last empty value in the order array
' this is a result of the count expanding the array after the value is added
ReDim Preserve arrOrder(UBound(arrOrder) - 1)
' Reset counter
cnt = 0
sum = 0
' For all the values in the order array
For i = LBound(arrOrder) To UBound(arrOrder)
' For all the values in the range
For j = 2 To UBound(arrData)
' If a row in the range matches the order letter add that value to the sum
If arrData(j, 1) = arrOrder(i) Then
sum = sum + arrData(j, 3)
' Keep track of the number of summed values for an average
cnt = cnt + 1
End If
Next j
Next i
' Calculte the average
avg = (sum / cnt)
' Pass the average back to the formula
Average_Orders_Subset = avg
End With
Set rng = Nothing
Set ws = Nothing
End Function