Hi everyone,
Thank you for reading this 
I've attached a workflow below, so you can see, that we have a dataset with 27 fields, but 2 of them will be not included in calculations.
Our input data looks like this. It is cumulative. We need to substract current month from next.
| Number | Name | Jan-19 | Feb-19 | Mar-19 | Apr-19 | May-19 | Jun-19 | Jul-19 | Aug-19 | Sep-19 | Oct-19 | Nov-19 | Dec-19 | Jan-20 | Feb-20 | Mar-20 | Apr-20 | May-20 | Jun-20 | Jul-20 | Aug-20 | Sep-20 | Oct-20 | Nov-20 | Dec-20 |
| 401 | Revenue | 1970 | 10293 | 15921 | 21229 | 24342 | 25103 | 32159 | 39810 | 42725 | 44384 | 49153 | 51264 | 9510 | 14454 | 22383 | 29941 | 32249 | 32647 | 38361 | 38903 | 39521 | 44473 | 50708 | 51589 |
What is the end result, that would be great to see:
| Number | Name | Jan-19 | Feb-19 | Mar-19 | Apr-19 | May-19 | Jun-19 | Jul-19 | Aug-19 | Sep-19 | Oct-19 | Nov-19 | Dec-19 | Jan-20 | Feb-20 | Mar-20 | Apr-20 | May-20 | Jun-20 | Jul-20 | Aug-20 | Sep-20 | Oct-20 | Nov-20 | Dec-20 |
| 401 | Revenue | 1970 | 8323 | 5628 | 5308 | 3113 | 761 | 7056 | 7651 | 2915 | 1659 | 4769 | 2111 | 9510 | 4944 | 7929 | 7558 | 2308 | 398 | 5714 | 542 | 618 | 4952 | 6235 | 881 |
First 2 fields could be dynamic, so end user should be able to choose which fields are not with values.
How do I see a workflow:
Split an input data into 2 datastreams. First contains "Number" and "Name" fields, that will not be used, and second - the rest of data.
We need to substract next column from current, but there are many periods, so we don't need to do it with the first month of year, so we need to make some kind of "Row-1" formula, but with fields, that will mean "if (contains[jan-19],"19") then [feb-19]-[jan-19] else [jan-19]).
But the trick is that [Jan-19] is first month, so how do we keep it?
P.S. We may have data with more years.