Are there convenient SAS functions for finding, say, the last Sunday in
October (which is the first day of daylight saving time)?

On Thu, 8 Jun 2006 10:44:08 -0400, Venky Chakravarthy <swovcc@HOTMAIL.COM>
wrote:

>On Thu, 8 Jun 2006 07:23:00 -0700, Paul <paulvonhippel@YAHOO.COM> wrote:
>
>>Are there convenient SAS functions for finding, say, the last Sunday in
>>October (which is the first day of daylight saving time)?
>
>Start in November and work backwards with INTNX. We can look for specific
>days of the week using week.1 for Sunday through week.7 Saturday. WEEK.1 is
>the default when you specify WEEK.
>
>329  data _null_ ;
>330    daylight = intnx ( "week" , "01NOV2006"d , -1 ) ;
>331    put daylight= : weekdate. ;
>332  run ;
>
>daylight=Sunday, October 22, 2006
>
>Venky Chakravarthy

As data _null_ has demonstrated the first backward interval is 0 and not -1
that I have used above. Shows that I didn't even look at the result
carefully. A bad thing when posting in a public forum. I had the right idea
but implemented it wrong.

Venky Chakravarthy

At bit more testing reveals that the enddate should be 31oct with
interval 0.  Or you get DLT ending on 01NOV in some years.

69   data _null_;
70      do year = 1990 to 2020;
71         dltB=intnx('WEEK',mdy(3,31,year),1);
72         dltE=intnx('WEEK',mdy(10,31,year),0);
73         put (dlt:) (=weekdate25.);
74         end;
75      run;

dltB=Sunday, Apr 1, 1990 dltE=Sunday, Oct 28, 1990
dltB=Sunday, Apr 7, 1991 dltE=Sunday, Oct 27, 1991
dltB=Sunday, Apr 5, 1992 dltE=Sunday, Oct 25, 1992
dltB=Sunday, Apr 4, 1993 dltE=Sunday, Oct 31, 1993


On 6/8/06, Venky Chakravarthy <swovcc@hotmail.com> wrote:
> On Thu, 8 Jun 2006 10:44:08 -0400, Venky Chakravarthy <swovcc@HOTMAIL.COM>
> wrote:
>
> >On Thu, 8 Jun 2006 07:23:00 -0700, Paul <paulvonhippel@YAHOO.COM> wrote:
> >
> >>Are there convenient SAS functions for finding, say, the last Sunday in
> >>October (which is the first day of daylight saving time)?
> >
> >Start in November and work backwards with INTNX. We can look for specific
> >days of the week using week.1 for Sunday through week.7 Saturday. WEEK.1 is
> >the default when you specify WEEK.
> >
> >329  data _null_ ;
> >330    daylight = intnx ( "week" , "01NOV2006"d , -1 ) ;
> >331    put daylight= : weekdate. ;
> >332  run ;
> >
> >daylight=Sunday, October 22, 2006
> >
> >Venky Chakravarthy
>
> As data _null_ has demonstrated the first backward interval is 0 and not -1
> that I have used above. Shows that I didn't even look at the result
> carefully. A bad thing when posting in a public forum. I had the right idea
> but implemented it wrong.
>
> Venky Chakravarthy
>

Data _null_,
I noticed the same thing, but you fix is not reliable since it depends on the fact that November 1 is not a Sunday.  Use
        dltE=intnx('WEEK',mdy(11,1,year)-1,0);
to guarantee that it works for all years.
Ian Whitlock
==========================
Date:         Thu, 8 Jun 2006 10:56:37 -0400
Reply-To:     "data _null_;" <datanull@GMAIL.COM>
Sender:       "SAS(r) Discussion"
From:         "data _null_;" <datanull@GMAIL.COM>
Subject:      Re: SAS date functions
Comments: To: Paul <paulvonhippel@yahoo.com>
In-Reply-To:  <1149776580.739735.316230@i40g2000cwc.googlegroups.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Does this look right?  I know it is for 2006.

41   data _null_;
42      do year = 2004,2005,2006;
43         dltB=intnx('WEEK',mdy(3,31,year),1);
44         dltE=intnx('WEEK',mdy(11,1,year),0);
45         put (dlt:) (=weekdate25.);
46         end;
47      run;

dltB=Sunday, Apr 4, 2004 dltE=Sunday, Oct 31, 2004
dltB=Sunday, Apr 3, 2005 dltE=Sunday, Oct 30, 2005
dltB=Sunday, Apr 2, 2006 dltE=Sunday, Oct 29, 2006


On 6/8/06, Paul <paulvonhippel@yahoo.com> wrote:
> Are there convenient SAS functions for finding, say, the last Sunday in
> October (which is the first day of daylight saving time)?
>