date2ISOweek: Converts date from standard notation to week notation...
In UweBlock/ISOweek: Week of the Year and Weekday According to ISO 8601

Description Usage Arguments Details Value Author(s) See Also Examples

Returns the year, the week of the year, and the day of week of a given date according to ISO 8601. It is an alternative to strftime(x, "%G-W%V-%u").

1	date2ISOweek(date)

date

Vector which can be coerced to class Date

The conversion specifications %g, %G, %u, %V where not available on Windows and MacOS before R 3.1.0. According to ISO 8601, the year of the week can differ from the calendar year (see the examples).

A character vector of year, week, and weekday in format "%G-W%V-%u"

Uwe Block u.block.mz@gmail.com

The inverse function ISOweek2date. strftime for a description of conversion specifications and references on ISO 8601.

x <- paste(1999:2011, "-12-31", sep = "")
y <- as.Date(x)
data.frame(date = format(y), weekdate = date2ISOweek(y))
data.frame(date = x, weekdate = date2ISOweek(x))