Hey @Yna_Db and thanks.
Your formula work but I’ve find another way to do it since my ask. (but it show me that I must learn a lot about Python code)
I use List.GroupByKey And use Math.sum with the Group and have another list with my key Appt.
Now I have 2 lists : Appt with unique key (A001, A002, A003, …) and Area with sum for each key.
Sorry for my late and thanks again @Yna_Db.
I’ve tried a lot of solution but it doesn’t work.
Now I’ve got 2 lists Surf. and Appt.
I’ve got a room with a parameter which value are A001 and A002 for the example.
I want to compare this parameter with APPT.list, obtain the index to find the SURF. List value and affect this value to my room.