ISOweek: Week of the year according to ISO 8601

In ISOweek: Week of the year and weekday 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

Details

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

Value

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

Author(s)

Hatto von Hatzfeld [e-mail], adopted to R by Uwe Block [e-mail]

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))

Example output

         date     week
1  1999-12-31 1999-W52
2  2000-12-31 2000-W52
3  2001-12-31 2002-W01
4  2002-12-31 2003-W01
5  2003-12-31 2004-W01
6  2004-12-31 2004-W53
7  2005-12-31 2005-W52
8  2006-12-31 2006-W52
9  2007-12-31 2008-W01
10 2008-12-31 2009-W01
11 2009-12-31 2009-W53
12 2010-12-31 2010-W52
13 2011-12-31 2011-W52
         date     week
1  1999-12-31 1999-W52
2  2000-12-31 2000-W52
3  2001-12-31 2002-W01
4  2002-12-31 2003-W01
5  2003-12-31 2004-W01
6  2004-12-31 2004-W53
7  2005-12-31 2005-W52
8  2006-12-31 2006-W52
9  2007-12-31 2008-W01
10 2008-12-31 2009-W01
11 2009-12-31 2009-W53
12 2010-12-31 2010-W52
13 2011-12-31 2011-W52

ISOweek documentation built on May 1, 2019, 10:08 p.m.