Date:         Thu, 24 Feb 2000 21:30:37 GMT
Reply-To:     stephno1@MY-DEJA.COM
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         stephno1@MY-DEJA.COM
Organization: Deja.com - Before you buy.
Subject:      Re: Macro question

Not where I am.  I am a fairly novice programer and am sure that some
of the code I produce is not the best - ie in terms of conservation of
time, resources, etc.  However, off-site training is rare and the
programmers I work with don't have the time to go through my code to
teach me from my mistakes.  I actually have gotten more help from this
list-serv than those around me.

In article <00287D66.C21292@westat.com>,
  WHITLOI1 <WHITLOI1@WESTAT.COM> wrote:
> Subject: Macro question
> Summary: Good programming is better than macro
> Respondent: Ian Whitlock <whitloi1@westat.com>
>
> Jeremy Miller <millerj@CALIB.COM> has written a macro to split a
> data set into 45 pieces and now wants to concatenate the pieces.
> His first macro is
>
> >    %macro datasets;
> >      %do i=1 %to 45;
> >        data dat&i(rename=(scr&i=scr res&i=res));
> >        set urn(keep=site_id clientid scr&i res&i);
> >        run;
> >      %end;
> >    %mend datasets;
>
> His question is how to write the second macro when for two data sets
> he has
>
> >    data dat3;
> >      set dat1 dat2;
> >      if scr=. | res=. then delete;
> >    run;
>
> There are two simple macro answers to this question, but the
> tragedy is that it shouldn't have been done in the first place.  No
> macro was necessary or desirable.
>
>      data result (keep = site_id clientid x scr res);
>         set urn(keep=site_id clientid scr1-scr45 res1-res45);
>         array _scr (45) scr1-scr45 ;
>         array _res (45) res1-res45 ;
>         do x = 1 to dim ( _scr ) ;
>            if _scr(x) ^=. and _res(x) ^=. then output ;
>         end ;
>      run ;
>
>      proc sort data = result ;
>         by x ;
>      run ;
>
> The sort is not needed if the order doesn't matter.  Then removing X
> from the KEEP list would be possible, but at the expense of losing
> information.  However that information was also lost in the question.
>
> Now let's look at two macro answers.
>
> >    %macro datasets;
> >      %do i=1 %to 45;
> >        data dat&i(rename=(scr&i=scr res&i=res));
> >          set urn(keep=site_id clientid scr&i res&i);
>            if _scr&i ^=. and _res&i ^=. ;
> >        run;
>          proc append base = result data = dat&i ;
>          run ;
> >      %end;
> >    %mend datasets;
>
> or
>
> >    %macro datasets;
>        %local dslist ;
> >      %do i=1 %to 45;
>          %let dslist = &dslist dat&i ;
> >        data dat&i(rename=(scr&i=scr res&i=res));
> >          set urn(keep=site_id clientid scr&i res&i);
> >        run;
> >      %end;
>
>   >    data dat3;
>          set &dslist ;
>   >      if scr=. | res=. then delete;
>   >    run;
>
> >    %mend datasets;
>
> Of course, there are many more answers with and without macro or
> arrays; but the real question is, how have we come teach programmers
> about SAS macro before they have learned good SAS programming
> techniques?
>
> At Westat the answer is that everyone is using SAS macro so new
> beginning programmers must learn some macro to be able to read the
> the programs that they have to modify.  The cost in terms of long
> complex programs has never been estimated nor the method even
> questioned.  Any different, anywhere else?
>
> Ian Whitlock
>


Sent via Deja.com http://www.deja.com/
Before you buy.