as.period: Change an object to a period.

Description

Change an object to a period.

Usage

as.period(x)

Arguments

an interval, difftime, or numeric object

Value

a period object

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.

Examples

Run this code

span <- new_interval(as.POSIXct("2009-01-01"), as.POSIXct("2010-02-02 01:01:01")) #interval
# [1] 2009-01-01 -- 2010-02-02 01:01:01
as.period(span)
# 1 year, 1 month, 1 day, 1 hour, 1 minute and 1 second}