RangeSum by multiple dimensions

[tschullo]

I am using QV12 and need to solve what seems like a simple problem:

Make	Model	MonYr	Sales	3MonSalesCnt
Ford	Pinto	Dec 2019	0	3
Ford	Pinto	Nov 2019	2	3
Ford	Pinto	Oct 2019	1	1
Ford	Escort	Dec 2019	1	2
Ford	Escort	Nov 2019	1	1
Ford	Escort	Oct 2019	0	0

I need a way to calculate 3MonSaleCnt (running count of sales for past 3 months)
I can't rely on the number of months always being >= 3 and the method must respect a change in Make and/or Model.
I am open to a script OR expression solution (personally, I prefer a script solution for dashboard efficiency's sake)

[Frank_Hartmann · Accepted solution]

Maybe try like this:

tmp:
Load *, (RowNo()) as Row;
Load * Inline [
Make,	Model,	MonYr_,	Sales	
Ford,	Pinto,	Dec 2019,	0
Ford,	Pinto,	Nov 2019,	2
Ford,	Pinto,	Oct 2019,	1
Ford,	Escort,	Dec 2019,	1
Ford,	Escort,	Nov 2019,	1	
Ford,	Escort,	Oct 2019,	0
];	
NoConcatenate

Load *,RangeSum(Sales,	If(Model = Peek(Model, -1), Peek(Sales,-1)),If(Model = Peek(Model, -2), peek(Sales,-2))) as [3Month] 
Resident tmp Order by Row desc; DROP Table tmp;

[tschullo]

Thank you Frank!

Simple yet elegant.

In my data there is a chance that the second dimension exists for multiple "Make" values, so I adjusted:

Load *,
RangeSum(Sales, If(Model = Peek(Model, -1) And Make = Peek(Make, -1), Peek(Sales,-1)),
                                     If(Model = Peek(Model, -2) And Make = Peek(Make, -2), peek(Sales,-2))
) as [3Month]
Resident tmp Order by Row desc;