Sum values based on the max of another field

[SI_NY02]

I'm trying to sum the quantity of based on the most recent activity. For example using the chart below sum the qty for each campaign based on the highest "purchased period" only.

Campaign Purchase period Qty

A 30 10

A 30 5

B 30 20

B 60 30

C 30 20

C 60 30

C 90 40

Answer should be:

A = 15

B = 30

C = 40

[BrunPierre · Accepted solution]

=Sum(Aggr(If([Purchase Period] = Max(TOTAL <Campaign> [Purchase Period]), Sum(Qty)), Campaign, [Purchase Period]))

[SI_NY02]

Thank you!