Durations display as the number of seconds in a time
span. When this number is large, durations also display
an estimate in larger units,; however, the underlying
object is always recorded as a fixed number of seconds.
For display and creation purposes, units are converted to
seconds using their most common lengths in seconds.
Minutes = 60 seconds, hours = 3600 seconds, days = 86400
seconds, weeks = 604800. Durations record the exact number of seconds in a time
span. They measure the exact passage of time but do not
always align with measurements made in larger units of
time such as hours, months and years. This is because the
length of larger time units can be affected by
conventions such as leap years and Daylight Savings Time.
Base R provides a second class for measuring durations,
the difftime class.
Duration objects can be easily created with the helper
functions dweeks
, ddays
,
dminutes
, dseconds
. These
objects can be added to and subtracted to date- times to
create a user interface similar to object oriented
programming.