Please see the picture. In the matrix pictured, an entry is considered "New Business" from the leftmost value + the next 11 columns (so 12 months total). I've highlighted this "window" in yellow. Anything to the right of that window is "Return Business". For each column/month, I need to calculate both the New & Return Business. I need a formula or some method to derive these two sums from one column. I only need to be able to get one of these, because then I could just subtract it from the total column sum for the other value.
In cell O6 the result is only $25 for each because the leftmost value on row 5 does not extend a full 12 months/columns before column O, so anything within that 12 month window is still considered "New" (I made this window blue so you could see it extends beyond the cell I'm trying to get a result for). All 11 columns to the right of the first value in a row could be populated, but they would all still be new. Only from the 13th column on would anything be considered "Return".
As you can see, the first value in each row does not always occur in the same spot, it moves.
The spreadsheet I am working with is 2,000+ rows. I actually went through and did this manually, but that was NOT fun! I manually found the leftmost value in each row, counted out 11 cells after it, and then colored the rest of the row yellow. Then I used a custom function that allowed me to sum based on cell color. So if there is a way to conditionally format the values, that would work too, I could use my color sum function.
Additionally, if there is a better way to do this in R, please let me know. I am new to R, but I imagine matrix math is easier/faster to do, but I've only played around with it a bit and I've never had to do anything like this in it.