Skip to main content
cancel
Showing results for 
Search instead for 
Did you mean: 

The Power BI Data Visualization World Championships is back! Get ahead of the game and start preparing now! Learn more

Reply
JollyRoger01
Helper III
Helper III

How to interpolate between monthly data (Excel Power Query)

I have some historical data (approximtely 1 month apart, but newer historical may be weekly) and someone has helped to interpolate the data so we have it daily chunks, however it is stepped rather than a linear line between the data periods. I'd like to linearly interpolate between these reporting periods. Would someone please be able to alter the Power Query for me to show this?

 

Interpolation

3 REPLIES 3
lbendlin
Super User
Super User

Here is a very simple and dirty trick that relies on some peculiar behavior of deduplication:

 

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("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", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Row Labels" = _t, #"Sum of Changes" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Row Labels", type date}, {"Sum of Changes", Int64.Type}}),
    #"Removed Duplicates" = Table.Distinct(#"Changed Type", {"Sum of Changes"})
in
    #"Removed Duplicates"

Hi Ibendlin, thank you for your answer. However, it is a little different from what I am actually after. You'll see my data has unique entries for each date, which I need to keep, with the exception of the Changes Completed. That I would like to interpolate between the months (reporting periods).

Please show the expected outcome. Not clear to me from your description.

Helpful resources

Announcements
Power BI DataViz World Championships

Power BI Dataviz World Championships

The Power BI Data Visualization World Championships is back! Get ahead of the game and start preparing now!

December 2025 Power BI Update Carousel

Power BI Monthly Update - December 2025

Check out the December 2025 Power BI Holiday Recap!

FabCon Atlanta 2026 carousel

FabCon Atlanta 2026

Join us at FabCon Atlanta, March 16-20, for the ultimate Fabric, Power BI, AI and SQL community-led event. Save $200 with code FABCOMM.