Date:         Mon, 20 Aug 2007 22:14:30 -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: How the function First. work in this case?

On Thu, 16 Aug 2007 16:45:56 -0400, Fehd, Ronald J. (CDC/CCHIS/NCPHI)
<rjf2@CDC.GOV> wrote:

>Either Don Henderson or Ian Whitlock
>came up with code for the subsetting do loop

It's useful for stuff other than subsetting.

>-- occasionally referrred to as the DOW loop --

Then if Don were getting the credit it would be a DoH loop.

>which uses either of:
>
>until(first.ByVar)
>
>until(last.ByVar)

It can use a variety of conditions in the UNTIL, depending on the situation.
However a FIRST-dot condition does not seem to be one of the useful ones.

>
>to read a dataset and output only the selected row
>
>I provide an example in this paper sgf2007.067:
>
>DO Which? Loop, UNTIL, or WHILE?
>A Review of DATA Step and Macro Algorithms
>
>http://www2.sas.com/proceedings/forum2007/067-2007.pdf
>
>Ron Fehd  the macro maven  CDC Atlanta GA USA RJF2 at cdc dot gov