How to Scan an Array and Return Custom Result in Excel

The SCAN function is a new dynamic array function available in Excel 365. It is used to apply a function to a sequence of values and accumulate the results. The function takes two arguments: the first argument is the sequence of values to apply the function to, and the second argument is the function to apply.

Syntax: SCAN(sequence, function)

The sequence argument can be a range of cells, an array, or a reference to another formula that returns a sequence of values. The function argument is a formula that takes two arguments: the accumulated result so far, and the current value in the sequence.

For example, suppose you have a column of numbers and you want to calculate the cumulative sum of those numbers. You can use the SCAN function with a lambda function to achieve this:

This formula starts by accumulating the first value in the sequence, which is the first cell in the range D1:D12. It then applies the lambda function to the accumulated value and the second value in the sequence, which is the second cell in the range. It continues this process until it has applied the lambda function to every value in the sequence. The result of the SCAN function is a dynamic array that contains the accumulated results for each value in the sequence.