Looks like you can convert to Julian date with the right origin and then
divide by 7, and take modulo 52. Something like:
julian(days, origin=days[1]-1) %/% 7 %% 52
That gets you 0-51. You just need to add one to get what you want. (I
subtract one from days[1] because it's a Monday. I'm sure you can
figure out how to do that programatically.)
Andy
From: Lauri Nikkinen
>
> R users,
>
> I have a vector of dates
>
> days <- seq(as.Date("2007/1/1"), as.Date("2008/1/31"), "days")
>
> and I would like to have week numbers from 1 to 52 for each year. How
> do I do that? Now I get 00-53 using
>
> format(days, "%W")
>
> > range(format(days, "%W"))
> [1] "00" "53"
>
> I have read "Date and Time Classes in R" (R news 01/04 by Gabor
> Grothendieck and Thomas Petzoldt) with no help.
>
> Thanks
> Lauri
>
> ______________________________________________
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>
>
>
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