JasonAizkalns - 6 months ago 46

R Question

Consider this sequence, which we can think of as "time between events"

`x <- c(5, 40, 3, 6, 0, 9, 0, 4, 5, 18, 2, 4, 3, 2)`

I would like to group these into buckets of 30, but buckets that reset. Desired outcome:

`output <- c(0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2)`

This is because, when we get to a cumulative 30, we "reset" and begin counting again. So,

`5 + 40 > 30`

`3 + 6 + 0 ...`

`x[10] == 18`

Answer

One option is to use `Reduce()`

to calculate the cumulative sum where you can set the `sum`

to be zero, when it exceeds some threshold:

```
cumsum(Reduce(function(x, y) if(x < 30) x + y else 0, x, acc = T) >= 30)
# [1] 0 1 1 1 1 1 1 1 1 2 2 2 2 2
```

Source (Stackoverflow)