John Mount solves a running total problem in Python:
An example of this is wanting to know any many reservations for a San Francisco Symphony concert scheduled for December 4th 2022 are known to have been made by October 22nd 2022. This could be used as part of an attendance demand model that is evaluated on October 22nd 2022. The “fifty-cent word” for this is “bitemporal” modeling or data.
As I read through the solution, my initial thought is that, if the data is in a relational database, a running total operation SUM(reservation_count) OVER (PARTITION BY target_date ORDER BY action_date ROWS BETWEEN UNBOUNDED PRECEDING TO CURRENT ROW) would form the basis of a solution. Still, this is an interesting exercise in translating a SQL operation into equivalent Python and just how much we get to take for granted.