weekdays {base}  R Documentation 
Extract the weekday, month or quarter, or the Julian time (days since some origin). These are generic functions: the methods for the internal datetime classes are documented here.
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("19700101", tz = "GMT"), ...) ## S3 method for class 'Date' julian(x, origin = as.Date("19700101"), ...)
x 
an object inheriting from class 
abbreviate 
logical vector (possibly recycled). Should the names be abbreviated? 
origin 
an lengthone object inheriting from class

... 
arguments for other methods. 
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 leapseconds.
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
.
weekdays(.leap.seconds) months(.leap.seconds) quarters(.leap.seconds) ## Julian Day Number (JDN, https://en.wikipedia.org/wiki/Julian_day) ## 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 https://en.wikipedia.org/wiki/Terrestrial_Time julian(Sys.Date(), 2440588) # from a day floor(as.numeric(julian(Sys.time())) + 2440587.5) # from a datetime