Iterative Calculation Over Time

[arhomberg]

Iterative Calculation

Hello all!

I could use some help with doing a calculation which I believe will end up being iterative.

In the table below, I would like to populate the count column (or a new column being that it’s a calculation) that takes the previous months (count * retention) + close_count

I am able to easily do this in excel but am not sure how to execute this in DAX.

I have included a project file for reference.

Any assistance with this would be greatly appreciated!

File: https://www.dropbox.com/s/p7yp3u066a1owu4/power_bi_example.pbix?dl=0

[lbendlin · Accepted solution]

Thank you for providing sample data.  (Next time please sanitize it)

This is impossible to do in Power BI DAX but relatively easy to achieve in Power Query M.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dc67DcAwCATQXagtzOH4wyyR918jTuMkKDRc8Q7EeZJoFmRVSqRsuGP0NYXNaKZVKE8B3GTlh4/NXmoobQuEUT3310vDvI7wrG0RbsUpJNoDQtFfmRc=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [fulldate = _t, close_count = _t, count = _t, retention = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"fulldate", type date}, {"close_count", type number}, {"count", type number}, {"retention", type number}}),
    #"Replaced Value" = Table.ReplaceValue(#"Changed Type",null,0,Replacer.ReplaceValue,{"close_count"}),
    #"Added Index" = Table.AddIndexColumn(#"Replaced Value", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "Count2", each List.Accumulate({1..[Index]},287,(state,current)=> state * #"Added Index"{current-1}[retention] + #"Added Index"{current-1}[close_count]))
in
    #"Added Custom"

How to use this code: Create a new Blank Query. Click on "Advanced Editor". Replace the code in the window with the code provided here. Click "Done".

[arhomberg]

@lbendlinAs a follow-up, I see that you have the value 287 hard coded in. Is it possible to select the value in the first row of the 'count' colum instead?

[lbendlin]

sure

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dc67DcAwCATQXagtzOH4wyyR918jTuMkKDRc8Q7EeZJoFmRVSqRsuGP0NYXNaKZVKE8B3GTlh4/NXmoobQuEUT3310vDvI7wrG0RbsUpJNoDQtFfmRc=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [fulldate = _t, close_count = _t, count = _t, retention = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"fulldate", type date}, {"close_count", type number}, {"count", type number}, {"retention", type number}}),
    #"Replaced Value" = Table.ReplaceValue(#"Changed Type",null,0,Replacer.ReplaceValue,{"close_count"}),
    #"Added Index" = Table.AddIndexColumn(#"Replaced Value", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "Count2", each List.Accumulate({1..[Index]},#"Added Index"{0}[count],(state,current)=> state * #"Added Index"{current-1}[retention] + #"Added Index"{current-1}[close_count]))
in
    #"Added Custom"

[arhomberg]

@lbendlinThank you!

[arhomberg]

@lbendlinThanks for the assistance with this, it is greatly appreciated!