Create or parse period objects
period() creates or parses a period object with the specified values.
period(num = NULL, units = "second", ...) is.period(x) seconds(x = 1) minutes(x = 1) hours(x = 1) days(x = 1) weeks(x = 1) years(x = 1) milliseconds(x = 1) microseconds(x = 1) nanoseconds(x = 1) picoseconds(x = 1) ## S3 method for class 'numeric' months(x, abbreviate)
num |
a numeric or character vector. A character vector can specify periods in a convenient shorthand format or ISO 8601 specification. All unambiguous name units and abbreviations are supported, "m" stands for months, "M" for minutes unless ISO 8601 "P" modifier is present (see examples). Fractional units are supported but the fractional part is always converted to seconds. |
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. When |
... |
a list of time units to be included in the period and their
amounts. Seconds, minutes, hours, days, weeks, months, and years are
supported. Normally only one of |
x |
Any R object for |
abbreviate |
Ignored. For consistency with S3 generic in base namespace. |
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.
Besides the main constructor and parser period(), period objects can also
be created with the specialized functions years(), months(), weeks(),
days(), hours(), minutes(), and seconds(). These objects can be added
to and subtracted to date-times to create a user interface similar to object
oriented programming.
Note: Arithmetic with periods can result in undefined behavior when
non-existent dates are involved (such as February 29th in non-leap years).
Please see Period for more details and %m+% and
add_with_rollback() for alternative operations.
a period object
### Separate period and units vectors
period(c(90, 5), c("second", "minute"))
# "5M 90S"
period(-1, "days")
period(c(3, 1, 2, 13, 1), c("second", "minute", "hour", "day", "week"))
period(c(1, -60), c("hour", "minute"))
period(0, "second")
### Units as arguments
period (second = 90, minute = 5)
period(day = -1)
period(second = 3, minute = 1, hour = 2, day = 13, week = 1)
period(hour = 1, minute = -60)
period(second = 0)
period(c(1, -60), c("hour", "minute"), hour = c(1, 2), minute = c(3, 4))
### Lubridate style parsing
period("2M 1sec")
period("2hours 2minutes 1second")
period("2d 2H 2M 2S")
period("2days 2hours 2mins 2secs")
period("2 days, 2 hours, 2 mins, 2 secs")
# Missing numerals default to 1. Repeated units are added up.
duration("day day")
### ISO 8601 parsing
period("P10M23DT23H") # M stands for months
period("10DT10M") # M stands for minutes
period("P3Y6M4DT12H30M5S") # M for both minutes and months
period("P23DT60H 20min 100 sec") # mixing ISO and lubridate style parsing
### Comparison with characters (from v1.6.0)
duration("day 2 sec") > "day 1sec"
### Elementary Constructors
x <- ymd("2009-08-03")
x + days(1) + hours(6) + minutes(30)
x + days(100) - hours(8)
class(as.Date("2009-08-09") + days(1)) # retains Date class
as.Date("2009-08-09") + hours(12)
class(as.Date("2009-08-09") + hours(12))
# converts to POSIXt class to accomodate time units
years(1) - months(7)
c(1:3) * hours(1)
hours(1:3)
# sequencing
y <- ymd(090101) # "2009-01-01 CST"
y + months(0:11)
# compare DST handling to durations
boundary <- ymd_hms("2009-03-08 01:59:59", tz="America/Chicago")
boundary + days(1) # period
boundary + ddays(1) # duration
is.period(as.Date("2009-08-03")) # FALSE
is.period(period(months= 1, days = 15)) # TRUEPlease choose more modern alternatives, such as Google Chrome or Mozilla Firefox.