Help creating a measure to show cumulative values by week and category within a matrix visual

[jboice]

Hi folks, Hopng someone can help show me how to create a measure to populate a matrix visual as described below

Here is an example of my source data:

Week	Category	Value
9/2/2023	A	1
9/2/2023	C	4
9/2/2023	D	5
9/9/2023	A	7
9/9/2023	B	3
9/9/2023	D	5
9/16/2023	A	4
9/16/2023	B	7
9/16/2023	C	8

From this data I am trying to create a matrix visual that resembles the following:

Week	Cumulative Value
9/2/2023	10
A	1
B	0
C	4
D	5
9/9/2023	25
A	8
B	3
C	4
D	10
9/16/2023	44
A	12
B	10
C	12
D	10
Total	44

Note each week includes the cumulative total up through that week, as well as the cumulative totals for each category (to show what is comprising the cumulative total at that week).

Each week shows all categories and their respective cumulative values through that week (or at least, each week should begin including them the first time they register a value, then continue including for subsequent weeks even in weeks when they do not register a new value)

Categories only appear in the data when they have registered a value for that week (otherwise they do not appear in the data for that week. For example in above data, Category "D" in week 9/16/2023)

Thank you for your help!

[lbendlin · Accepted solution]

create a proper data model

To report on things that are not there you need to use a crossjoin and a measure.

Cumul = 
var w = max(Weeks[Week])
return 0+CALCULATE(sum(Facts[Value]),Weeks[Week]<=w)

[jboice]

Brilliant, thank you!