strptime

R Base 3.6.2

Functions to convert between character representations and objects of classes "POSIXlt" and "POSIXct" representing calendar dates and times.

Syntax

# S3 method for POSIXct
format(x, format = "", tz = "", usetz = FALSE, &#8230;)
# S3 method for POSIXlt
format(x, format = "", usetz = FALSE, &#8230;)<p></p><p># S3 method for POSIXt
as.character(x, &#8230;)</p><p>strftime(x, format = "", tz = "", usetz = FALSE, &#8230;)
strptime(x, format, tz = "")</p>

Arguments

Parameter	Description
`x`	An object to be converted: a character vector for strptime, an object which can be converted to "POSIXlt" for strftime.
`tz`	A character string specifying the time zone to be used for the conversion. System-specific (see as.POSIXlt), but "" is the current time zone, and "GMT" is UTC. Invalid values are most commonly treated as UTC, on some platforms with a warning.
`format`	A character string. The default for the format methods is "%Y-%m-%d %H:%M:%S" if any element has a time component which is not midnight, and "%Y-%m-%d" otherwise. If options("digits.secs") is set, up to the specified number of digits will be printed for seconds.
`…`	Further arguments to be passed from or to other methods.
`usetz`	logical. Should the time zone abbreviation be appended to the output? This is used in printing times, and more reliable than using "%Z".

Return Value

The format methods and strftime return character vectors representing the time. NA times are returned as NA_character_. The elements are restricted to 256 bytes, plus a time zone abbreviation if usetz is true. (On known platforms longer strings are truncated at 255 or 256 bytes, but this is not guaranteed by the C99 standard.) strptime turns character representations into an object of class "POSIXlt". The time zone is used to set the isdst component and to set the "tzone" attribute if tz != "".

Details

The format and as.character methods and strftime convert objects from the classes "POSIXlt" and "POSIXct" to character vectors. strptime converts character vectors to class "POSIXlt": its input x is first converted by as.character. Each input string is processed as far as necessary for the format specified: any trailing characters are ignored. strftime is a wrapper for format.POSIXlt, and it and format.POSIXct first convert to class "POSIXlt" by calling as.POSIXlt (so they also work for class "Date"). Note that only that conversion depends on the time zone. The usual vector re-cycling rules are applied to x and format so the answer will be of length of the longer of these vectors. Locale-specific conversions to and from character strings are used where appropriate and available. This affec

Examples

Example

# NOT RUN {
## locale-specific version of date()
format(Sys.time(), "%a %b %d %X %Y %Z")

## time to sub-second accuracy (if supported by the OS)
format(Sys.time(), "%H:%M:%OS3")

## read in date info in format 'ddmmmyyyy'
## This will give NA(s) in some non-English locales; setting the C locale
## as in the commented lines will overcome this on most systems.
## lct <- Sys.getlocale("LC_TIME"); Sys.setlocale("LC_TIME", "C")
x <- c("1jan1960", "2jan1960", "31mar1960", "30jul1960")
z <- strptime(x, "%d%b%Y")
## Sys.setlocale("LC_TIME", lct)
z

## read in date/time info in format 'm/d/y h:m:s'
dates <- c("02/27/92", "02/27/92", "01/14/92", "02/28/92", "02/01/92")
times <- c("23:03:20", "22:29:56", "01:03:30", "18:21:03", "16:56:26")
x <- paste(dates, times)
strptime(x, "%m/%d/%y %H:%M:%S")

## time with fractional seconds
z <- strptime("20/2/06 11:16:16.683", "%d/%m/%y %H:%M:%OS")
z # prints without fractional seconds
op <- options(digits.secs = 3)
z
options(op)

## time zone names are not portable, but 'EST5EDT' comes pretty close.
(x <- strptime(c("2006-01-08 10:07:52", "2006-08-07 19:33:02"),
               "%Y-%m-%d %H:%M:%S", tz = "EST5EDT"))
attr(x, "tzone")

## An RFC 5322 header (Eastern Canada, during DST)
## In a non-English locale the commented lines may be needed.
## prev <- Sys.getlocale("LC_TIME"); Sys.setlocale("LC_TIME", "C")
strptime("Tue, 23 Mar 2010 14:36:38 -0400", "%a, %d %b %Y %H:%M:%S %z")
## Sys.setlocale("LC_TIME", prev)

## Make sure you know what the abbreviated names are for you if you wish
## to use them for input (they are matched case-insensitively):
format(seq.Date(as.Date('1978-01-01'), by = 'day', len = 7), "%a")
format(seq.Date(as.Date('2000-01-01'), by = 'month', len = 12), "%b")
# }