The function isoWeekYear
extracts the year and week of a
Date
according to the ISO 8601 specification.
Arguments
- Y
year(s) or a Date/POSIXt object. Can be a vector.
- M
month(s), only used if Y
is not a Date/POSIXt object.
- D
day(s), only used if Y
is not a Date/POSIXt object.
Value
A list with entries ISOYear
and ISOWeek
containing the
corresponding results.
Note
As from surveillance 1.17.0, this function simply
calls strftime
with format strings "%G"
and "%V"
, respectively, as this is nowadays (R >= 3.1.0)
also supported on Windows.
Examples
dates <- as.Date(c("2002-12-31","2003-01-01","2003-01-06"))
isoWeekYear(dates)
## the same using numeric inputs:
isoWeekYear(Y = c(2002, 2003, 2003), M = c(12, 1, 1), D = c(31, 1, 6))