as.period
Change an object to a period.
Change an object to a period.
Usage
as.period(x, units)Arguments
- x
- an interval, difftime, or numeric object
- units
- a character vector. The names of the units to divide the
period among. Years, months, days, hours, minutes, and seconds are
supported, see
standardise_date_namesfor more details. The largest
Details
as.period changes interval, duration (i.e., difftime) and numeric objects to period objects with the specified units.
Users must specify which time units to measure the period in. The
length of each time unit in a period depends on when it occurs. See
periods. The choice of units is not trivial; units that
are normally equal may differ in length depending on when the time
period occurs. For example, when a leap second occurs one minute is
longer than 60 seconds.
Because periods do not have a fixed length, they can not be
accurately converted to and from duration objects. Duration objects
measure time spans in exact numbers of seconds, see
duration. Hence, a one to one mapping does not exist
between durations and periods. When used with a duration object,
as.period provides an inexact estimate; the duration is broken into
time units based on the most common lengths of time units, in
seconds. Because the length of months are particularly variable, a
period with a months unit can not be coerced from a duration object.
For an exact transformation, first transform the duration to an
interval with as.interval.
Value
- a period object
See Also
Examples
span <- new_interval(as.POSIXct("2009-01-01"), as.POSIXct("2010-02-02 01:01:01")) #interval
# 397.0424 days beginning at 2009-01-01
as.period(span)
# 1 year, 1 month, 1 day, 1 hour, 1 minute and 1 second
as.period(span, units = c("year"))
# 1 year and 2768461 seconds
as.period(span, units = c("day", "minute"))
# 1 day, 1 minute and 34218001 seconds}