Calculate average based on dynamic column reference

Hello BartVW 

in order to create a dynamically solution, you have to tell us what can be a rule, to select the correct columns. Here an example where I calculated the average of all columns that contain a ".". If this is your requirement, you can use the code, otherwise tell us all names of your columns, and we will find another logic. Replace the source-step and changedtype with your real data table

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUTICYmMgNgFiUyA2A2JzpdhYAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, #"007.2020" = _t, #"008.2020" = _t, #"009.2020" = _t, #"010.2020" = _t, Result = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", Int64.Type}, {"Column2", Int64.Type}, {"007.2020", Int64.Type}, {"008.2020", Int64.Type}, {"009.2020", Int64.Type}, {"010.2020", Int64.Type}, {"Result", Int64.Type}}),
    AddAverageOfMonths = Table.AddColumn
    (
        #"Changed Type",
        "AverageMonth",
        (row)=> List.Average(Record.FieldValues(Record.SelectFields(row, List.Select(Table.ColumnNames(#"Changed Type"), each Text.Contains(_,".")))))
    )
in
    AddAverageOfMonths

Copy paste this code to the advanced editor in a new blank query to see how the solution works.

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Kudoes are nice too

Have fun

Jimmy