From samandrew at gmx.ch  Fri Dec 11 22:25:13 2009
From: samandrew at gmx.ch (samandrew at gmx.ch)
Date: Fri, 11 Dec 2009 22:25:13 +0100 (CET)
Subject: [Rd] Calendar week ISO (PR#14132)
Message-ID: <20091211212513.73E592833EE0@mail.pubhealth.ku.dk>

Hi there

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I use Gnu R sometimes at work.=20

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Unfortunately we use Windows and R has problems with getting the calendar
week number with the first week as the one which has at least 4 days. A
colleague told me that he has the same problem.=20

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Below you can see what I use now, for finding the right week.=20

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Kind regards,=20

Samuel Andreas Meichtry

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#Excel-Funktion

#=3DK=DCRZEN((A3-DATUM(JAHR(A3+3-REST(A3-2;7));1;REST(A3-2;7)-9))/7)

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#R-Funktion

KW<-function(x){=20=20=20=20

    return(floor(

    as.numeric((x-(as.Date(ISOdate(

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as.numeric(format(as.Date(as.numeric(x)+3+25569-2-(as.numeric(x)-2+25569)%%7
,origin=3D"1900-01-01"),"%Y")),1,1)

    )+((as.numeric(x)-2+25569)%%7-9)-1))/7)))=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20

}

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tmp.d <- seq(as.Date("1970-01-01"),as.Date("2009-01-01"),"days")

df<-data.frame(TimeStamp=3Dtmp.d,KW=3DKW(tmp.d))

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[Rd] Calendar week ISO (PR#14132)
samandrew at gmx.ch