Exponential Moving Average in Power Query M ?

[jsflint]

Hello! How can an exponential moving average be created in Power Query M?  I already know how to do this in Excel, and DAX can be a pain in the tail.  Here's a table of example data.  Thank you!

Date Value
1/1/2021 0.888073856
1/2/2021 0.087243733
1/3/2021 0.597531606
1/4/2021 0.25492501
1/5/2021 0.836644673
1/6/2021 0.253785258
1/7/2021 0.757333787
1/8/2021 0.958886707
1/9/2021 0.598108137
1/10/2021 0.180565909
1/11/2021 0.788755716
1/12/2021 0.888126908
1/13/2021 0.231740519
1/14/2021 0.107410191
1/15/2021 0.648458581
1/16/2021 0.582213204
1/17/2021 0.191300599
1/18/2021 0.864502562
1/19/2021 0.583108477

[Fowmy · Accepted solution]

@jsflint 

Can you share the expected value based on the sample data that you have given?

You can save the  Excel file with the results in One Drive or Google Drive and share the link 

[jsflint · Accepted solution]

Ema 

Here it is

[Fowmy · Accepted solution]

@jsflint 

Can you share the expected value based on the sample data that you have given?

You can save the  Excel file with the results in One Drive or Google Drive and share the link 

[jsflint · Accepted solution]

Ema 

Here it is

[Fowmy · Accepted solution]

@jsflint 

Please find attached the PBIX file below my signature with the desired results. Basically, the solution involves a recursive operation to calculate the EMA ( Exponential Moving Average in Power Query ).

There are two columns, Average and EMA.

Complete M Code:

let
  Source = Table.FromRows(
    Json.Document(
      Binary.Decompress(
        Binary.FromText(
          "VZLbbQRBCARz2e+TD5p3LNbln4Y5adnB3yVmmqJ/fy9+8xsEvl4X/Qghwwp2fV5fhIPY3BERuJEchFRIROmN9CAXB2Ua38gOSmEmS5Ib+UGVIdIobxQHGbsEdFLkIqlM7E/2Wu+hxDV5AjIdFmUIE58YvHQwJZX1d8OWD3PWkqL5jpeQTsim5jVsGSEEzEzGCC8lkZbO5bMdLydiZar8+OfYc17gHhy2tDi+xjrMsOVF4CQVz3WwvGSHJCedOfA+Qh8uO+qw5YWCoBJDdk24L+TBswGWFe3FJeMxhl2UXlz6eHMhbCtpndGmKFhSssvaZdYnypJC3YYyz4fVv4aBvOt8fT5/",
          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", type number}}
  ),
  Step1 = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1, Int64.Type),
  Step2 = Table.AddColumn(
    Step1,
    "Average",
    each if [Index] > 6 then List.Average(List.Range(Step1[Value], _[Index] - 7, 7)) else null
  , type number),
  Step3 = Table.AddColumn(
    Step2,
    "EMA",
    each
      if [Index] > 6 then
        let
          start = List.First(List.RemoveNulls(Step2[Average])),
          vlist = List.Range(Step2[Value], 8, _[Index] - 7),
          acc = List.Accumulate(
            vlist,
            start,
            (state, current) => (current - state) * (2 / (1 + 7)) + state
          )
        in
          if [Index] = 7 then start else acc
      else
        null,
  type number )
in
    Step3

[jsflint]

Hey @Fowmy , first of all the code you sent works awesome!  However, I've been ultimately trying to create a Triple Exponential Moving Average, and I figure I could just reuse a good part of the code to create a second and third EMA then calculate a final column to create a TEMA.  It's not working out for me right now, and I'd greatly appreciate your assistance again.  I've attached another sample Excel file that includes date, value, average, ema1,  ema2,  ema3, and Tema columns.  The formulas are present, and hopefully makes sense.  Thanks again!!!

TEMA