That’s not possible, even though yes it’d be nice! You might be able to generate a list of date ranges, each date range is a list of two dates …
Possibly with a date range, not sure how you’d process the period if its being in a date form though …
The usual approach is to give the graph multiple lists, one for each dimension or axis or property, where the same item number means the same point to be graphed.
If inside the map function you returned an object containing the original value, as well as the delta, you can still sort the list of obects by its delta property. Then either:
a) return to Bubble a list of date ranges, or
I should probably read your use case during daylight hours to understand it more, haha.