R presents more of a challenge to Stata on many fronts, one of which is basic data management.
I often find myself calculating the value of one observation given the value of an adjacent value. For example, to assess a lagged effect, I would take the value of the preceding interval. Stata makes this really easy, R not so much.
Here's what we would do in Stata:
set obs 1000
gen i = _n
gen val = round(runiform()*10)
gen lag = val[_n-1]
The last command throws the warning,
(1 missing value generated) because the first observation has no lagged observation. The first 10 observations look like this: