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