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Friday, October 07, 2005

Another SAS Function Friday

Friday again already?! Doesn't it seem like time speeds up around Autumn? Something about the shortening days, the changing weather, the new TV line-up, the expectation of the holiday season soon approaching... I dunno, maybe it's just me?

For some crazy reason all this ruminating on days shortening kinda reminds me of one of my favorite SAS functions: intnx(). How's that for a weak tie-in? :)

Intnx() is used to increment a SAS date/time/datetime value by a given interval and returns a SAS date/time/datetime value. The following syntax should be enough to get you started, refer to SAS documentation for more details:

dt = intnx( 'INTERVAL', dateTime, increment <,alignment> );
Where dt is the date/time/datetime value returned,
INTERVAL is a time interval (WEEK, MONTH, HOUR, etc),
dateTime is a SAS date/time/datetime value,
increment is a positive or negative integer which specifies the number of intervals to shift the value,
and alignment controls the position of the shifted value within the interval (BEGINNING|MIDDLE|END|SAMEDAY). Default is beginning.

Got it? How about an example:

data _null_;
* take todays date and shift it forward two months;
thisDay = today();
forward2Months = intnx('MONTH', thisDay, 2, 'SAMEDAY');
put forward2Months= mmddyy10.;

We specified SAMEDAY as the fourth argument instead of letting it default to BEGINNING which would have given us a date of 12/01/2005 instead of 12/07/2005.

Ready to test out your new function? I've always been confused about what day is the first day of the week? A quick google search gets me a very infomative page which states:

The Bible clearly makes the Sabbath the last day of the week, but does not share how that corresponds to our 7 day week. Yet through extra-biblical sources it is possible to determine that the Sabbath at the time of Christ corresponds to our current 'Saturday.' Therefore it is common Jewish and Christian practice to regard Sunday as the first day of the week (as is also evident from the Portuguese names for the week days). However, the fact that, for example, Russian uses the name "second" for Tuesday, indicates that some nations regard Monday as the first day.

In international standard ISO-8601 the International Organization for Standardization (ISO) has decreed that Monday shall be the first day of the week.

So for you SAS trivia buffs out there, figure out which day SAS considers to be the first day of the week. Does it follow the Judeo-Christian standard of Sunday? Or bend to the ISO-8601 standard of Monday?

Happy Friday!

1 comment:

  1. What if you want to know the last day of each month? January ends on the 31st, February sometimes ends on the 28th, April ends on the 30th, etc..

    And you are using V8.

    Enter INTNX.