Date:         Wed, 24 Dec 2003 14:47:04 -0500
Reply-To:     "Richard A. DeVenezia" <radevenz@IX.NETCOM.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Richard A. DeVenezia" <radevenz@IX.NETCOM.COM>
Subject:      Re: Using RETAIN  to reorder with a Name Prefix list (colon
              specifica              tion)

"Chakravarthy, Venky" <Venky.Chakravarthy@PFIZER.COM> wrote in message
news:303682BAB5176E47941169F3C8444778B1B6DE@anagrdexm03.research.aa.wl.com...
> Hi,
>
> There have been several discussions on the list about reordering
variables.
> It is even on the SASware ballot. One of the popular methods discussed is
to
> use a RETAIN statement before the SET statement.
>
> I observed something today while using a RETAIN statement to reorder the
> variables in a data set. When a name prefix list (such as a:) is used to
> specify a range of variables those variables get put at the end even if
they
> were in the beginning in the original. Even worse, it seems to completely
> ignore the specified relative order of such groups of variables. If the
> original order is c: and a: and you want a: and c: and specify that in the
> RETAIN, it is ignored. The original order is maintained. See below for a
> simple illustration. Any explanations? Has this been covered before?
snip
>
> Venky Chakravarthy


in:  c1 c2 a1 a2 b

retain a: b c: ;
set foo;

out: b c1 c2 a1 a2

This is totally my expectation, and hope fully others.

At the compile time step prior to the retain statement there are no pdv
variables.

a: b c: -> after the retain statement the compiler knows there is a variable
named b (possibly) and possibly variables whose names start with a and
variables whose names start with c.

at the set statment the compiler knows there are variables
c1 c2 a1 a2 b

one must know infer that full formed variable names in a retain statement
take ordering precedence, followed by the order of the incoming data vector.
Since the a: and c: are not fully formed, the order of variables (in the
pdv) matching the a: c: specification will be the same as the incoming data
set.

b - fully specified in retain
c1 - matches c: of retain, order per incoming dv
c2 - matches c: of retain , order per incoming dv
a1 - matches a: of retain , order per incoming dv
a2- matches a: of retain, order per incoming dv

--
Richard A. DeVenezia
http://www.devenezia.com/downloads/sas/macros/?m=hash-macros