difftime                package: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 or date 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': see 'strptime'. 
          The default is a locale-specific time format.

       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
     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 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.

See Also:

     'DateTimeClasses'.

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

