SpaDES modules commonly use approximate durations that divide with no
remainder among themselves.
For example, models that simulate based on a "week" timestep, will likely
want to fall in lock step with a second module that is a "year" timestep.
Since, weeks, months, years don't really have this behaviour because of:
leap years, leap seconds, not quite 52 weeks in a year, months that are of
different duration, etc.
We have generated a set of units that work well together that are based on
the astronomical or "Julian" year.
In an astronomical year, leap years are added within each year with an extra
1/4 day, (i.e., 1 year == 365.25 days); months are defined as year/12, and
weeks as year/52.
dhour(x)
dmin(x)
dday(x)
dyears(x)
# S4 method for class 'numeric'
dyears(x)
dmonths(x)
# S4 method for class 'numeric'
dmonths(x)
dweeks(x)
# S4 method for class 'numeric'
dweeks(x)
dweek(x)
dmonth(x)
dyear(x)
dsecond(x)
dNA(x)
# S4 method for class 'ANY'
dNA(x)Number of seconds within each unit
When these units are not correct, a module developer can create their own
time unit, and create a function to calculate the number of seconds
in that unit using the "d" prefix (for duration), following the
lubridate package standard:
ddecade <- function(x) lubridate::duration(dyear(10)).
Then the module developer can use "decade" as the module's time unit.