I need to do a complex sort involving large amounts of data.

Hello, I have posted before HERE.

To reiterate, I work at a library and I essentially need to do a review of hundreds of thousands of lines of data compiling information about different periodical volumes into one line. They are technically all different volumes (and there is a column for that) but can be organized under a single periodical title.

The raw output data will look something like this:

Periodical A / Volume 1 / Last Loaned Date / Usage Number

Periodical A / Volume 2 / Last Loaned Date / Usage Number

Periodical A / Volume 3 / Last Loaned Date / Usage Number

Periodical A / Volume 4 / Last Loaned Date / Usage Number

Periodical B / Volume 1 / Last Loaned Date / Usage Number

Periodical B / Volume 2 / Last Loaned Date / Usage Number

etc.

What I need to do is find some way of sorting or filtering or some algorithm that can first, take only the most recent date from the Last Loaned Date column among all volumes, and eliminate all others. Second, take the sum of all Usage Numbers for all volumes of that periodical and put it into a single number. Third, combine these two things into one line for the periodical in question.

So the output should look something like:

Periodical A / Last Loaned Date (most recent) / Usage Number (total among all)

Periodical B / Last Loaned Date (most recent) / Usage Number (total among all)

In this way I hope to get hundreds of thousands of lines of data down to about 50,000, representing the number of different periodicals we hold at the library.

I have now moved to Excel 365 and am trying to implement the solution recommended by u/Downtown-Economics26 HERE: LINK.

However, even the test case is not working for me. I am instead getting a NAME? error in the execution. This is what I see: LINK.

I think I am using the exact same function as him, and I have Excel 365 so I can use DROP and GROUPBY functions, but I am still getting an error. Does anyone know why this might be the case?