Date:         Mon, 7 Aug 2006 23:04:16 -0400
Reply-To:     "Howard Schreier <hs AT dc-sug DOT org>" <nospam@HOWLES.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Howard Schreier <hs AT dc-sug DOT org>" <nospam@HOWLES.COM>
Subject:      Re: first none missing date

On Mon, 7 Aug 2006 09:40:10 -0700, Richard Gong <gongcon@GMAIL.COM> wrote:

>* Hi,
>
>I have the following data set (test) and try to create two new variables
>start_date and end_date. The start_date is the first none missing date and
>the end date is the last none-missing date.
>
>data* test;
>input patno date date9.;
>format date date9.;
>datalines;
>1 .
>1 09JUL1994
>1 05JUL1994
>1 .
>1 27JUL1994
>run;
>
>*The final result will be the following:*
>patno date        start_date   end_date
>1       .         05JUL1994    27JUL1994 1     09JUL1994   05JUL1994
>27JUL1994
>1     05JUL1994   05JUL1994    27JUL1994
>1       .         05JUL1994    27JUL1994
>1     27JUL1994   05JUL1994    27JUL1994
>
>
>I tried to *sort* the data set first *by* patno and date and use retain and
>*first.*patno to assign the value, but the problem is that I don't know how
>to deal with the missing value.

Try this

   data start_end;
   keep patno start_date end_date;
   set test;
   by patno;
   retain start_date end_date;
   if first. patno then do;
      start_date = .;
      end_date = .;
      end;
   if     missing(start_date) then start_date = date;
   if not missing      (date) then   end_date = date;
   if last.patno then output;
   format start_date end_date date9.;
   run;

>
>Best Regards
>
>gongcon