How to show Top20 rows in Pivot table?

[#1]

Hello, I need to show top20 products that have maximum sales in a specific period, in a specific time, in a specific shop .. . .
I can do that in Straight table by using the limiting option in dimension tab, but pivot table doesn't allow me to do.
Anyone, can come up with the solution for me? Thanks in advance.

[AbhijitBansode · Accepted solution]

Try using Rank function in calculated dimension:

If( Aggr(Rank(Sum(Sales)),<PeriodField>,<ShopField>)<=20,Product)

[#3]

If( Aggr(Rank(Sum(Sales)),<PeriodField>,<ShopField>)<=20,Product)

This one ranks and filters top20, but on the measure, it should show measure (Sales), but here its showing me Products name in measure area.    

[AbhijitBansode]

use Sum(Sales) as Expression to your pivot table.