Calculate Week number difference in header column

Hello Anonymous 

It's not 100% clear what you need. But if you have a table with all column names that can be transformed in dates and you would like to use the first column as as start and rename the other with the time distance in weeks then you can use this approach. But bear in mind that you will have problems whenever you have

- other column names that are not dates and should not be considered in the renaming

- if you have another date-format (like Feb 15) you need to find a way to transform your date into a week

- when you are crossing a year, my approach will not work anymore

Here the code

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUTICYmOl2FgA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"15.02.21" = _t, #"22.02.21" = _t, #"02.03.21" = _t]),
    GetFirstColumnAsDate = Date.From(Table.ColumnNames(Source){0},"de-DE"),
    GetRenamedColumns = Table.TransformColumnNames
    (
        Source,
        (columnName) => if Date.From(columnName, "de-DE") = GetFirstColumnAsDate then columnName else "W+" & Text.From(Date.WeekOfYear(Date.From(columnName))-Date.WeekOfYear(GetFirstColumnAsDate))
    )
    
in
    GetRenamedColumns

before

after

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

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Have fun

Jimmy