Running total with two criteria - seeking arrayformula or app script

Question

I have a google sheet with a list of [people], [dates], and [times]. I need a running total column that gives me a running time total on each line for each combination of name and date, as of that line. I have a working SUMIFS solution. The drawback of this solution is that it requires me to copy the formula down the entire column. Since I ultimately want this to work in a sheet that is fed by a form, I want to use either an ARRAYFORMULA or an APP SCRIPT solution, so that each new row will automatically do the calculation without my needing to copy down the formula.

You can see what I mean in this sample sheet:

https://docs.google.com/spreadsheets/d/1G6cgwwcL6LfnbVUhn8PrMYxrUSImkmgOGvPspparhSI/edit?usp=sharing

Thanks for any thoughts you may have.

-DH

Answer 1

SUMIF() does not play nice with ARRAYFORMULA(). Have a look at this MMULT example spreadsheet, last sheet "Cumulative sum down column", column U

https://docs.google.com/spreadsheets/d/1NJPAt5iFQWIyxHx35bpCh6zjVeKon4rdTPk-dfyZDrU/edit#gid=420781522

If you haven't used matrix multiplication before, and have trouble wrapping your head around the solution, try to follow the examples starting from the 1st sheet.