title: Aggregate by most recent not-null value
body: <p>I have a dataset with the following columns [ product_id, country_id, date, number_of_installs, cumulative_installs_last_30_days ]</p>
  
  <p>I have no problem applying the standard measures to find the sum, max or average number_of_installs within those three dimensions (product_id, country_id, date(aggregated by month or week)). However, I have not been able to aggregate by cumulative_installs_last_30_days because as that variable is already a cumulative, I need to return the “most recent value” and Tableau does not have that option built-in the aggregation functions. </p>
  
  <p>How do I create a Calculated Field that enables an addicional column in the aggregated dataset with the most recent not-null value of cumulativeInstalls_last_30_days within the dimensions product_id, country_id and date(aggregated by month or week)?</p>