Lookup to value of previous year

[Anonymous]

Hi everyone,

I have the following table in PowerQuery:

Date	Value
01/01/2000	23655
01/01/2001	36985
01/01/2002	65987

I would like to add a colomn with the year-to-year growth. This means that for each row, I would look up the value of the year before and divide it and substract 1. I know how to do this with DAX, but in my use case I need to make use of M Query language and I am not finding any resources online. Could anyone help me with this?

[Vijay_A_Verma · Accepted solution]

See the working here - Open a blank query - Home - Advanced Editor - Remove everything from there and paste the below code to test (later on when you use the query on your dataset, you will have to change the source appropriately. If you have columns other than these, then delete Changed type step and do a Changed type for complete table from UI again)

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMtQ31DcyMDBQ0lEyMjYzNVWK1YELGgIFjc0sLVAEjYCCZqaWFuZKsbEA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, Value = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Value", Int64.Type}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "%YoY", each try Number.Round([p=List.Buffer(#"Added Index"[Value]){[Index]-1}, YoY= ([Value]-p)/p*100][YoY],2) otherwise null, type number),
    #"Removed Columns" = Table.RemoveColumns(#"Added Custom",{"Index"})
in
    #"Removed Columns"

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[Anonymous]

Hi, I forgot to mention, the table actually looks like this:

Date	Country	Value
01/01/2000	DE	12345
01/01/2001	DE	6789
01/01/2000	FR	4567
01/01/2001	FR	1236

How can I achieve the same but the growth numbers are calculated per country? Thanks!