Accamulated data in pivot mode

Question

Now i accamulate columns via row_cumsum

test
| project Boenheter, Ar, Maned, ManedTLA 
| extend _date = make_datetime(toint(Ar), Maned, 1) 
| extend key1 = Ar, __auto0 = datetime_part('Month', startofmonth(_date)) 
| summarize value0 = sum(Boenheter) by key1, __auto0, ManedTLA 
| order by __auto0 asc, key1 asc 
| serialize value0 = **row_cumsum(value0, __auto0 != prev(__auto0))** 
| extend __p = pack(tostring(ManedTLA), value0) 
| summarize __p = make_bag(__p) by key1 
| evaluate bag_unpack(__p) 
| order by key1 asc

But i wanna do accamulation for rows in next approach: Feb = Jan + Feb, Mar = Jan + Feb + Mar, etc... so Feb = 304, Mar = 624 (for 2012 year as example) and so on

Does Kusto have some hack for do accamulation for row instead columns (row_cumsum)?

Help please)

Answer 1

Use row_cumsum, with restart on year change, before using pivot

// Generation of a data sample. No part of the solution.
let t = materialize(range i from 1 to 200 step 1 | extend dt = ago(365d*10*rand()));
// The solution starts here.
t
| summarize count() by year = getyear(dt), month = format_datetime(dt,'MM')
| order by year asc, month asc
| extend cumsum = row_cumsum(count_, year != prev(year))
| evaluate pivot(month, any(cumsum), year)

year	01	02	03	04	05	06	07	08	09	10	11	12
2012					2	4		6	7	10	14	16
2013	2	3	7	8	10	11	15	16		17		18
2014	2	7	11	12	13	14	15		17		19	20
2015	2	3	6			10	11	12		13	14	15
2016	1	2	3	5	6	8	10	11	12	15	16	19
2017	1	2	5	8	13	16		17	20			21
2018	4	5	8	12		15	18	20	23	24	25	26
2019	5	7	8		10	11	14	18		19	20	21
2020	2	5	8	10	11		13	15	16	19	22
2021	2		5	6			7	8	9	11		17
2022		2	4	5

Fiddle