Avoiding loops in R

Question

I have decided to learn R. I am trying to get a sense of how to write \"R style\" functions and to avoid looping. Here is a sample situation:

Given a vector a<

Answer 1

You can also use a combination of cumsum and diff to get the sum over sliding windows. You'll need to pad with your own NaN, though:

> speed <- c(1,1,1,1,1,4,6,3,6,8,9)
> diff(cumsum(c(0,speed)), 5)/5
[1] 1.0 1.6 2.6 3.0 4.0 5.4 6.4