Calculate a sum for each period of INDEX. Essentially a rolling
application of sum over a series of non-overlapping sections.
Usage
period.sum(x, INDEX)
Arguments
x
a univariate data object
INDEX
a vector of breakpoints to calculate sum on
Value
A numeric vector of sums per period.
Details
Used to calculate a sum per period given an arbitrary
index of sections to be calculated over. This is an optimized function
for sum. There are additionally optimized versions for min, max, and
prod.