Cumulative Mean
Calculates the cumulative mean of a vector.
x (Vector): The input numeric
vector.
na_rm (Bool): = false Remove NA
values before computation.
The cumulative mean.
cummean([1, 2, 3])
-- Returns = [1.0, 1.5, 2.0]
cummean([1, NA, 3], na_rm = true)
-- Returns = [1.0, 1.0, 2.0]