insert multiple columns that subtract previous columns

[Syndicate_Admin]

Hello - I have 50+ columns that I need to calculate the difference after every 2 columns. Currently I appended my tables in Power Query and it looks like this:

DRAFT	ACTUAL	DRAFT	ACTUAL
10	15	20	10
5	4	30	100
1	2	40	50

I need it to do this:

DRAFT	ACTUAL	DIFF	DRAFT	ACTUAL	DIFF
10	15	(5)	20	10	10
5	4	1	30	100	(70)
1	2	(1)	40	50	(10)

I can add a custom column in Power query but it shows up at the end of the table and then I have to move it. Also, it is very manual and I have to do this for 50+ columns on 50+ files.

[Syndicate_Admin]

I should add that each of my files has a different number of columns as well. So if I can automate to add this difference column for any number of iterations as there is data, that is what I want to do.

[Anonymous · Accepted solution]

Hi ,

Please refer to this:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("JYqxDQAwCMN+ydyhQOkziP/fKEkXK5FdBdtYsBy4lmCDCPQq0Bzeb8lU7dIsnYkEcVjfi+4H", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [DRAFT = _t, ACTUAL = _t, DRAFT.1 = _t, ACTUAL.1 = _t, DRAFT.2 = _t, ACTUAL.2 = _t]),
    ColumnNames = Table.ColumnNames(Source),
    ChangeType = Table.TransformColumnTypes(Source, List.Transform(ColumnNames, each {_, type number})),
    AddDiffColumns = List.Accumulate(
        List.Zip({{0..List.Count(ColumnNames)-1}, ColumnNames}),
        ChangeType,
        (state, current) => 
            if Number.Mod(current{0}, 2) = 1 then 
                let
                    diffColumnName = "DIFF" & Text.From(Number.IntegerDivide(current{0}, 2) + 1),
                    draftColumnName = ColumnNames{current{0}-1},
                    actualColumnName = current{1},
                    addedDiffColumn = Table.AddColumn(state, diffColumnName, each Record.Field(_, draftColumnName) - Record.Field(_, actualColumnName), type number)
                in
                    addedDiffColumn
            else 
                state
    )
in
    AddDiffColumns

Best Regards,
Gao
Community Support Team

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