DateTimeClasses

R Base 3.6.2

Description of the classes "POSIXlt" and "POSIXct" representing calendar dates and times.

Syntax

# S3 method for POSIXct
print(x, tz = "", usetz = TRUE, max = NULL, &#8230;)<p></p><p># S3 method for POSIXct
summary(object, digits = 15, &#8230;)</p><p><code>time + z</code>
<code>z + time</code>
<code>time - z</code>
<code>time1 lop time2</code></p>

Arguments

Parameter	Description
`x, object`	an object to be printed or summarized from one of the date-time classes.
`tz, usetz`	for timezone formatting, passed to format.POSIXct.
`max`	numeric or NULL, specifying the maximal number of entries to be printed. By default, when NULL, getOption("max.print") used.
`digits`	number of significant digits for the computations: should be high enough to represent the least important time unit exactly.
`…`	further arguments to be passed from or to other methods.
`time`	date-time objects
`time1, time2`	date-time objects or character vectors. (Character vectors are converted by as.POSIXct.)
`z`	a numeric vector (in seconds)
`lop`	one of ==, !=, <, <=, > or >=.

Details

There are two basic classes of date/times. Class "POSIXct" represents the (signed) number of seconds since the beginning of 1970 (in the UTC time zone) as a numeric vector. Class "POSIXlt" is a named list of vectors representing sec0--61: seconds. min0--59: minutes. hour0--23: hours. mday1--31: day of the month mon0--11: months after the first of the year. yearyears since 1900. wday0--6 day of the week, starting on Sunday. yday0--365: day of the year. isdstDaylight Saving Time flag. Positive if in force, zero if not, negative if unknown. zone(Optional.) The abbreviation for the time zone in force at that time: "" if unknown (but "" might also be used for UTC). gmtoff(Optional.) The offset in seconds from GMT: positive values are East of the meridian. Usually NA if unknown, but 0 could mean

Examples

Example

# NOT RUN {
<!-- % <--> may fail / be platform dependent -->
(z <- Sys.time())             # the current date, as class "POSIXct"

Sys.time() - 3600             # an hour ago

as.POSIXlt(Sys.time(), "GMT") # the current time in GMT
format(.leap.seconds)         # the leap seconds in your time zone
print(.leap.seconds, tz = "PST8PDT")  # and in Seattle's
# }
# NOT RUN {
<!-- % ..test should be diffable from here on: -->
# }
# NOT RUN {
## look at *internal* representation of "POSIXlt" :
leapS <- as.POSIXlt(.leap.seconds)
names(leapS) ; is.list(leapS)
## str() "too smart" -->  need unclass(.):
utils::str(unclass(leapS), vec.len = 7)
## Extracting *single* components of POSIXlt objects:
leapS[1 : 5, "year"]

##  length(.) <- n   now works for "POSIXct" and "POSIXlt" :
for(lpS in list(.leap.seconds, leapS)) {
    ls <- lpS; length(ls) <- 12
    l2 <- lpS; length(l2) <- 5 + length(lpS)
    stopifnot(exprs = {
      ## length(.) <- * is compatible to subsetting/indexing:
      identical(ls, lpS[seq_along(ls)])
      identical(l2, lpS[seq_along(l2)])
      ## has filled with NA's
      is.na(l2[(length(lpS)+1):length(l2)])
    })
}
# }
# NOT RUN {
<!-- % for -->
# }

DateTimeClasses

Syntax

Arguments

Details

Examples

See Also