getting ISO week

On Thu, Dec 11, 2008 at 2:10 PM, Prof Brian Ripley

A slightly simpler version is

format(Sys.Date(), "%V")


On Thu, 11 Dec 2008, Prof Brian Ripley wrote:

strftime(x, "%V")

E.g.

strftime(as.POSIXlt(Sys.Date()), "%V")

is "50", and you might want as.numeric() on it.

Note that this is OS-dependent, and AFAIR Windows does not have it.

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On Thu, Dec 11, 2008 at 2:15 PM, Gabor Grothendieck

format(d, "%U") and format(d, "%W") give week numbers using
different conventions.  See ?strptime

Thank you both for your replies!

I'm on windows, so prof Ripleys solution does not work (why is this
OS-dependent?).
Regarding Gabor's solution, neither convention follow the ISO 8601
standard, which is used in Europe (and Sweden in particular). See
http://en.wikipedia.org/wiki/ISO_8601#Week_dates .
So it seems that my function does fill a hole, however small....

I know that for me, working with week numbers, which are used quite
heavily in Sweden, have always been a major frustration.
Would it be possible to implement something similar to my solution in
base, and how should I go about making it fit in to the rest of the
date functions?

/Gustaf

Gustaf Rydevik, M.Sci.
tel: +46(0)703 051 451
address:Essingetorget 40,112 66 Stockholm, SE
skype:gustaf_rydevik