period
Create a period object.
period creates a period object with the specified values.
period provides the behaviour of new_period
in a way that is more suitable for automating within a
function.
Usage
period(num, units = "second")Arguments
- num
- a numeric vector that lists the number of time units to be included in the period
- units
- a character vector that lists the type of units to be used. The units in units are matched to the values in num according to their order.
Details
Within a Period object, time units do not have a fixed length (except for seconds) until they are added to a date-time. The length of each time unit will depend on the date-time to which it is added. For example, a year that begins on 2009-01-01 will be 365 days long. A year that begins on 2012-01-01 will be 366 days long. When math is performed with a period object, each unit is applied separately. How the length of a period is distributed among its units is non-trivial. For example, when leap seconds occur 1 minute is longer than 60 seconds.
Periods track the change in the "clock time" between two date-times. They are measured in common time related units: years, months, days, hours, minutes, and seconds. Each unit except for seconds must be expressed in integer values.
Period objects can be easily created with the helper
functions years, months,
weeks, days,
minutes, seconds. These
objects can be added to and subtracted to date-times to
create a user interface similar to object oriented
programming.
Value
- a period object
See Also
Examples
period(c(90, 5), c("second", "minute"))
# "5M 90S"
period(-1, "days")
# "-1d 0H 0M 0S"
period(c(3, 1, 2, 13, 1), c("second", "minute", "hour", "day", "week"))
# "20d 2H 1M 3S"
period(c(1, -60), c("hour", "minute"))
# "1H -60M 0S"
period(0, "second")
# "0S"