aggregate using the rank measure

Hi , xnatsu24 

According to your description, you create a rank measure to get the rank . And you want to group by the rank and get the average of the value .

Here are the steps you can refer to :
(1)This is my test data and my understand for your need:

(2) We can click "New Table" to create a dimension table :

Table 2 = var _max_count = MAXX(SUMMARIZE('Table','Table'[Month],"count" ,  COUNT('Table'[Bank])) , [count])
return
GENERATESERIES(1,_max_count,1)

(3)Then we can click "New Measure" and enter this to create a measure:

Measure = var _t =ADDCOLUMNS( SUMMARIZE('Table','Table'[Month],'Table'[Bank],"value", SUM('Table'[Value])) , "rank" , [rank])
var _cur_rank = VALUES('Table 2'[Value])
return
AVERAGEX(FILTER(_t, [rank] in _cur_rank) , [value])

Then we can put the fields we need on the visual and we can get this:

If this method does not meet your needs, you can provide us with your special sample data and the desired output sample data in the form of tables, so that we can better help you solve the problem. (You can also upload you sample .pbix [without sensitive data] to the OneDrive and share with the OneDrive link to me ! )

Thank you for your time and sharing, and thank you for your support and understanding of PowerBI! 

Best Regards,

Aniya Zhang

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