Top N + others for whole period

[vulpix999]

Hi!
I have this DAX code for a measure, which calculates the investment value for Top N advertisers and for the "others" group. 

In short, it:

1. Takes the top N advertisers by invested value (where N is specified in the 'TopN Selection' table).
2. Calculates the investments for these top N advertisers.
3. Groups all other advertisers (those not in the top N) into the "Other" category.
4. Calculates the investment amount for the entire "Other" category.
   
   

It's all good if I want to display it as a total, but if I put it in a graph/table that shows the result in different periods, it calculates a new Top N for each period. 

An example for a visual result:
What I need: The measure calculates a Top 3 for the whole data period, then shows how much each of the three advertisers spent each month. 
What I have now: The measure calculates a Top 3 for each of the months, in result having a ton on different advertisers in one graph. 

Here is a screenshot of the code:

Here is the code:

TOPN Investment (A) =

// Get the selected value for the number of top advertisers to consider.
VAR TOPNSelected = SELECTEDVALUE('TopN Selection'[Top player count])

// Get the currently selected advertiser.
VAR CurrentAdvertiser = SELECTEDVALUE('Pseudo Advertiser Table'[Advertiser])

// Calculate the top N advertisers based on the 'Investment type' measure.
VAR TopAdvertisers = TOPN(TopNSelected, ALLSELECTED('Pseudo Advertiser Table'[Advertiser]), 'Investment type measure'[Investment type])

// Calculate the investment amount for the top advertisers, preserving other filters.
VAR TopAdvertiserSales = CALCULATE('Investment type measure'[Investment type], KEEPFILTERS(TopAdvertisers))

RETURN

// Check if there's only one selected advertiser.
IF(HASONEVALUE('Pseudo Advertiser Table'[Advertiser]),

// If one advertiser selected, switch based on its category.
SWITCH(TRUE(),

// If the selected advertiser is not "Others," return investment for top N advertisers.
CurrentAdvertiser <> "Others", TopAdvertiserSales,

// If the selected advertiser is "Others," calculate investment for the "Other" category.
CurrentAdvertiser = "Others",
CALCULATE('Investment type measure'[Investment type], ALLSELECTED('Pseudo Advertiser Table'[Advertiser]))
- CALCULATE('Investment type measure'[Investment type], TopAdvertisers)
),

// If multiple advertisers selected, return investment for the current advertiser.
'Investment type measure'[Investment type]
)

...

I think it must be something with the filters inside the measure? I'm not sure since I'm no pro in PBI, I mainly just followed this link to create a Top N + others formula.

If anyone can help me modify this formula so that the TOP is based on the total period and stays the same regardless of how I visualize it,  it would be largely appreciated!

[amitchandak]

@vulpix999 , Please refer if my approach can help

Power BI- TOPN with Others- https://youtu.be/I_TY4hVlzAE

https://medium.com/microsoft-power-bi/power-bi-topn-others-8b094203a306

[vulpix999]

Hello! I appreciate your response, but the method you've shared still has the same problem I mentioned. When visualizing the result over various periods, for example - years, it calculates a new Top for each year. However, I require the Top to be determined based on the entire period and remain constant during visualization.