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weekdays {base}

Extract Parts of a POSIXt or Date Object
Package: 
base
Version: 
R 2.15.3

Description

Extract the weekday, month or quarter, or the Julian time (days since some origin). These are generic functions: the methods for the internal date-time classes are documented here.

Usage

weekdays(x, abbreviate)
 
## S3 method for class 'POSIXt':
weekdays((x, abbreviate = FALSE))

## S3 method for class 'Date':
weekdays((x, abbreviate = FALSE)

months(x, abbreviate))

## S3 method for class 'POSIXt':
months((x, abbreviate = FALSE))

## S3 method for class 'Date':
months((x, abbreviate = FALSE)

quarters(x, abbreviate))

## S3 method for class 'POSIXt':
quarters((x, ...))

## S3 method for class 'Date':
quarters((x, ...)

julian(x, ...))

## S3 method for class 'POSIXt':
julian((x, origin = as.POSIXct("1970-01-01", tz = "GMT"), ...))

## S3 method for class 'Date':
julian((x, origin = as.Date("1970-01-01"), ...))

Arguments

x
an object inheriting from class "POSIXt" or "Date".
abbreviate
logical. Should the names be abbreviated?
origin
an length-one object inheriting from class "POSIXt" or "Date".
...
arguments for other methods.

Values

weekdays and months return a character vector of names in the locale in use.

quarters returns a character vector of "Q1" to "Q4".

julian returns the number of days (possibly fractional) since the origin, with the origin as a "origin" attribute. All time calculations in R are done ignoring leap-seconds.

Note

Other components such as the day of the month or the year are very easy to compute: just use as.POSIXlt and extract the relevant component. Alternatively (especially if the components are desired as character strings), use strftime.

See Also

DateTimeClasses, Date

Examples

weekdays(.leap.seconds)
months(.leap.seconds)
quarters(.leap.seconds)
 
## Julian Day Number (JDN, <a href="http://en.wikipedia.org/wiki/Julian_day" title="http://en.wikipedia.org/wiki/Julian_day">http://en.wikipedia.org/wiki/Julian_day</a>)
## is the number of days since noon UTC on the first day of 4317 BC.
## in the proleptic Julian calendar.  To more recently, in
## 'Terrestrial Time' which differs from UTC by a few seconds
## See http://en.wikipedia.org/wiki/Terrestrial_Time
julian(Sys.Date(), -2440588) # from a day
floor(as.numeric(julian(Sys.time())) + 2440587.5) # from a date-time

Documentation reproduced from R 2.15.3. License: GPL-2.