Konverter dato til ugenummer

Her nogle koder jeg fandt via Google cache på http://www.keysolutions.com/NotesFAQ/all6x.html
Men linket virker ikke direkte.
Jeg tror Ken E. Yee 's server er nede eller lignende

Men her er koden. Det er faktisk 2 løsninger.

This formula satisfies ISO 8601:1988:


REM "This formula satisfies ISO 8601:1988";
REM "Formulae updated : 08.28.1997 ";
REM "by Stephen P.R. Renton (sprenton@mcmail.com)";
REM "Version: 1.01";
REM "Tested on : Lotus Notes Release 4.5";

REM "D is the date of interest.";
D := @TextToTime(@Prompt([OKCANCELEDIT]; "Enter Date"; "Please enter a
date to convert to a week number:"; ""));
REM "D := [31/12/95]";

FirstOfYear := @Date(@Year(D); 1; 1);
LastOfYear := @Date(@Year(D); 12; 31);
FirstDayNum := @Weekday(FirstOfYear);
LastDayNum := @Weekday(LastOfYear);

REM "ISO weeks start on Monday and ends on Sunday.";
ISOFirstDayNum := @If(FirstDayNum = 1; 7; FirstDayNum - 1);
ISOLastDayNum := @If(LastDayNum = 1; 7; LastDayNum - 1);

REM "The first and last ISO week is the first";
REM "and last ISO week to include Thursday";
IsFirstWeek := 7 - ISOFirstDayNum > 2;
IsLastWeek := 7 - ISOLastDayNum < 4;
REM "The date of the first day of the first ISO week";
ISOFirstDay := @If(IsFirstWeek;
            @Adjust(FirstOfYear; 0; 0; 1 - ISOFirstDayNum; 0; 0; 0);
            @Adjust(FirstOfYear; 0; 0; 8 - ISOFirstDayNum; 0; 0; 0));
REM "The date of the last day of the last ISO week";
ISOLastDay := @If(IsLastWeek;
            @Adjust(LastOfYear; 0; 0; 7 - ISOLastDayNum; 0; 0; 0);
            @Adjust(LastOfYear; 0; 0; -ISOLastDayNum; 0; 0; 0));

REM "Date outside ISOFirstDay and ISOlastDay";
REM "are from the previous or next year";
REM "Return the ISO week number and exit";

FirstWeekNextYear := @If(D > ISOLastDay; @Return(@Prompt([OK]; "FWNY";
@Text(@Year(D)+1) + "W01")); NULL);

REM "I suspect this is where Julian dates would be useful";
REM "A recursive call could be used in a real language";
LastWeekLastYear := (D - @Adjust(FirstOfYear; -1; 0; 0; 0; 0; 0))/60/60/24/7;
AdjustLastWeek := 1 - (LastWeekLastYear - @Integer(LastWeekLastYear));
@Set("LastWeekLastYear"; LastWeekLastYear + AdjustLastWeek);
@If(D < ISOFirstDay;
@Return(@Prompt([OK]; "LWLY"; @Text(@Year(D) - 1) + "W" +
@Text(LastWeekLastYear))); NULL);

REM "If you get this far, the date falls into an ISO week this year";
REM "Convert the difference in seconds to weeks";
NumWeeks := (D - ISOFirstDay)/60/60/24/7;

REM "Fractions indicate that the date falls";
REM "in the middle of the ISO week";
WeekAdjust := 1 - (NumWeeks - @Integer(NumWeeks));
ISOWeekNum := NumWeeks + WeekAdjust;

REM "Conform to ISO 8601 format";
Pad:=@If(ISOWeekNum<10;"0";"");
Result := @Text(@Year(D))+"W"+Pad+@Text(ISOWeekNum);

@Prompt([OK];"Week number"; Result)

Here is another version that gives you a week number in another ISO format:


REM "Formulae Calculate the Week Number(01-53) for any Date. ";
REM "The output follows the ISO 8601:1988 standard: ex 1997-W31-4 for 1997.07.31 ";
REM "Formulae writer : Nikolai Aasen (nsaa@pvv.org), UNI Storebrand, Norway";
REM "Formulae written : 1997.07.30";
REM "Formulae updated : 1997.08.04";
REM "Version  : 1.03";
REM "Tested on  :Lotus Notes 4.6PreRelease2";
REM "This formulae is available in the";
REM "Lotus Notes FAQ: http://www.keysolutions.com/NotesFAQ/";
REM "More Calendar information in http://www.pip.dknet.dk/~pip10160/calendar.html";
REM "ISO 8601:1988 summary at: http://quake.stanford.edu/~lyle/ISOdate/Date.html";
REM "--------------------------------------------------------------------------------------------------";           
REM "Replace D with the date of interest.";
D := [1997.31.07];

REM "**************************";
REM"Calculate some data for this Year";
REM "**************************";
FirstOfYear := @Date(@Year(D); 1; 1);
LastOfYear := @Date(@Year(D); 12; 31);
FirstDayNum := @Weekday(FirstOfYear);
REM "ISO weeks start on Monday and ends on Sunday.";
ISOFirstDayNum := @If(FirstDayNum = 1; 7; FirstDayNum - 1);

REM " Week 1 of any year is the week that contains the first Thursday in January.";
REM "=1 if 1. jan = man - thu. WeekNumber is then 1, else 0";
IsFirstWeek := 7- ISOFirstDayNum >2;

REM "The first Monday after 1. jan this Year";
FirstMonday := 9 - ISOFirstDayNum;

REM "Number of Days from 1. jan to D";
DaysToDateD:=(D-FirstOfYear)/60/60/24+1;

REM "Number of days in Year(either 365 or 366)";
DaysInYear:=(LastOfYear-FirstOfYear)/60/60/24;

REM "Number of Weeks in Year. Most years have 52 weeks, but years that start on a
Thursday and leapyears that start on a Wednesday have 53 weeks.";
NumberOfWeeksThisYear:=@If( (ISOFirstDayNum=4 | (ISOFirstDayNum=3 &
DaysInYear=366));53;52 );

REM "***************************";
REM"Calculate some data for last Year  ";
REM "***************************";
FirstOfLastYear := @Date(@Year(D)-1; 1; 1);
LastOfLastYear := @Date(@Year(D)-1; 12; 31);
FirstDayNumLast := @Weekday(FirstOfLastYear);
REM "ISO weeks start on Monday and ends on Sunday.";
ISOFirstDayNumLast := @If(FirstDayNumLast = 1; 7; FirstDayNumLast - 1);

REM "Number of days in Year(either 365 or 366)";
DaysInYearLast:=(LastOfLastYear-FirstOfLastYear)/60/60/24;

REM "Number of Weeks Last Year. Most years have 52 weeks, but years that start on a
Thursday and leapyears that start on a Wednesday have 53 weeks.";
NumberOfWeeksLastYear:=@If( (ISOFirstDayNumLast=4 | (ISOFirstDayNumLast =3 &
DaysInYearLast=366));53;52 );

REM "************************";
REM"Calculates the Week Number  ";
REM "************************";



DDayNum := @Weekday(D);
ISODDayNum := @If(DDayNum = 1; 7; DDayNum - 1);

REM"Is D in the last Week of the last Year?";
DayInLastWeek := @If((DaysToDateD<FirstMonday & IsFirstWeek = 0);
                                @Return( @Text(@Year(D)-1)+"-W"+@Text(NumberOfWeeksLastYear)+"-"+@Text(ISODDayNum));
                                NULL);

REM "Calculate number of Complete Weeks Between D and 1.jan";
ComplNumWeeks:=@Integer((DaysToDateD-FirstMonday)/7);

REM "Are there remaining days?";
RemainingDays:=@If( (DaysToDateD+1-(FirstMonday+7*ComplNumWeeks))>0);

NumWeeks:= IsFirstWeek+ComplNumWeeks+1;

Out :=
@If(RemainingDays;
@If( (NumWeeks>52 & NumWeeks>NumberOfWeeksThisYear );
        @Return(@Text(@Year(D)+1)+"-W01-"+ @Text(ISODDayNum));
          @Return(@Text(@Year(D))+"-W"+@Right("0"+@Text(NumWeeks);2)+"-"+@Text(ISODDayNum)));
@Return(@Text(@Year(D))+"-W"+@Right("0"+@Text(NumWeeks-1);2) +"-"+@Text(ISODDayNum)));

Nu har jeg ikke 'regnet' ovenstående igennem ;-)

Men husk at være opmærksom på at der ikke er global enighed om hvornår en uge starter og slet ikke om hvornår året starter. Så vær sikker på at den kode du vælger rent faktisk er den korrekte i forhold til den standard som du ønsker at overholde.

Vær også opmærksom på at hvis din kode skal benyttes på historiske data, så var år 2000 ikke skudår, selvom det er fire år siden og vi har skudår i år. Mange kodeeksempler tager ikke højde for dette.

>>pr0gm4n

-- præcis 2000 var skudår, som en af de (ret !-) sjældne 100-år ...

Reglen er (efter den gregorianske kalender, som i Danmark blev indført i år 1700), at år, som ender på 00, kun er skudår, hvis 400 går op i årstallet, dvs.

1700, 1800 og 1900 er _ikke_ skudår, men 2000 og 2400 er !o]