Time series data? (access array sibling)

#1

We are trying to create a data set of store level sales data that changes over time. In a simple version each store would have:
store id
store location
sales[20]

Where each value of sales represents a quarter of sales data. The trick is that the first value of sales is randomized and the each subsequent value is based off the sales[i-1]*growthrate. What I can’t find is any way to reference a sibling array element in a formula. Is this possible?

#2

You can’t refer to a previous element in the array, but you can refer to field in the parent object, so you could do something like this: