Cumulative sum until maximum reached, then repeat from zero in the next row

Question

I feel like this is a fairly easy question, but for the life of me I can\'t seem to find the answer. I have a fairly standard dataframe, and what I am trying to do is sum th

Answer 1

I still don't understand about when the sum should restart and if it should be zero then. A desired result would help greatly.

Nonetheless, I can't help but think that simply indexing and subtraction would be a straightforward way of doing this. The below code gives the same result as @Henrik's solution.

df$difference_sum <- cumsum(df$difference)
step <- (df$difference_sum %/% 1470) + 1
k <- which(diff(step) > 0) + 1
df$keep <- 0
df$keep[k] <- 1
step[k] <- step[k] - 1
df$difference_sum <- df$difference_sum - c(0, df$difference_sum[k])[step]