ISOweek (version 0.6-2)

ISOweek: Week of the year according to ISO 8601

Description

This function returns the year and the week of the year of a given date according to ISO 8601. It is an substitute for the %Y-W%V format which is not implemented on Windows.

Usage

ISOweek(date)

Arguments

date

Vector which can be coerced to class Date

Value

A character vector of year and week in format "%Y-W%V"

Details

According to ISO 8601, the year of the week can differ from the calendar year (see the examples).

References

http://www.salesianer.de/util/kalwoch.html

See Also

strptime for a description of the date formats and references on ISO 8601. isoWeekYear for an alternative implementation.

Examples

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