Selecting the last value of a column

Question

I have a spreadsheet with some values in column G. Some cells are empty in between, and I need to get the last value from that column into another cell.

Something li

Answer 1

I have gone through way too many of these implementations of last-row for a specific column. Many solutions work but are slow for large or multiple datasets. One of my use cases requires me to check the last row in specific columns across multiple spreadsheets. What I have found is that taking the whole column as a range and then iterating through it is too slow, and adding a few of these together makes the script sluggish.

My "hack" has been this formula:

=ROW(index(sheet!A2:A,max(row(sheet!A2:A)*(sheet!A2:A<>""))))-1

• Example: Add this to Cell A1, to find the last row in column A. Can be added anywhere, just make sure to manage the "-1" at the end depending on which row the formula is placed. You can also place this is another col, rather than the one you're trying to count, and you don't need to manage the -1. You could also count FROM a starting Row, like "C16:C" - will count values C16 onwards

• This formula is reliably giving me the last row, including blanks in the middle of the dataset

• To use this value in my GS code, I am simply reading the cell value from A1. I understand that Google is clear that spreadsheet functions like read/write are heavy (time-consuming), but this is much faster than column count last-row methods in my experience (for large datasets)

• To make this efficient, I am getting the last row in a col once, then saving it as a global variable and incrementing in my code to track which rows I should be updating. Reading the cell every-time your loop needs to make an update will be too inefficient. Read once, iterate the value, and the A1 cell formula (above) is "storing" the updated value for the next time your function runs

Please let me know if this was helpful to you! If I encounter any issues I will comment on this answer.