R: Time Intervals

difftime {base}

R Documentation

Time Intervals

Description

Create, print and round time intervals.

Usage

time1 - time2

difftime(time1, time2, tz = "",
         units = c("auto", "secs", "mins", "hours", "days", "weeks"))

as.difftime(tim, format = "%X")

## S3 method for class 'difftime':
round(x, digits = 0)

Arguments

`time1, time2`	date-time objects.
`tz`	a timezone specification to be used for the conversion. System-specific, but `""` is the current time zone, and `"GMT"` is UTC.
`units`	character. Units in which the results are desired. Can be abbreviated.
`tim`	character string specifying a time interval.
`format`	character specifying the format of `tim`.
`x`	an object inheriting from class `"difftime"`.
`digits`	integer. Number of significant digits to retain.

Details

Function difftime takes a difference of two date/time objects (of either class) and returns an object of class "difftime" with an attribute indicating the units. There is a round method for objects of this class, as well as methods for the group-generic (see Ops) logical and arithmetic operations.

If units = "auto", a suitable set of units is chosen, the largest possible (excluding "weeks") in which all the absolute differences are greater than one.

Subtraction of two date-time objects gives an object of this class, by calling difftime with units="auto". Alternatively, as.difftime() works on character-coded time intervals.

Limited arithmetic is available on "difftime" objects: they can be added or subtracted, and multiplied or divided by a numeric vector. In addition, adding or subtracting a numeric vector implicitly converts the numeric vector to a "difftime" object with the same units as the "difftime" object.

Examples

(z <- Sys.time() - 3600)
Sys.time() - z                # just over 3600 seconds.

## time interval between releases of 1.2.2 and 1.2.3.
ISOdate(2001, 4, 26) - ISOdate(2001, 2, 26)

as.difftime(c("0:3:20", "11:23:15"))
as.difftime(c("3:20", "23:15", "2:"), format= "%H:%M")# 3rd gives NA