Chang,

I agree with your assessment of Richard's code.  I especially liked that he offered it without any chest pounding!

Joe

-----Original Message-----
From: "Chang Y. Chung" <chang_y_chung@HOTMAIL.COM>
Sent: Jan 16, 2004 11:19 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Re: Assign variables to a new variable based on variable names in              SAS

Hi, Richard,

Your data step, "monkeyshines" is one of the prettest I have ever seen.
Really nice.

The to-the-point array statement using the variable name wild character
(":"); use of lbound() hbound() functions; use of _i_ for index variable;
short but intuitive variable and array names like aVars, aBase, and aMap;
use of intnx and intck functions, reading the returned variable name
with ??yyq6. format, anticipation of range checking, and all the work was
done in essentially a single line!("a_new = aVars[aMap[qtrIndex]];") ... I
learn a lot just by reading your code!

All I could come up(at the bottom) was, in comparison, uh... ugly... slow,
and lacked much of the error checking and handling. Even though it is not
a wallpaper code... :-)

Cheers,
Chang

>data monkeyshines;
>  set faux;
>  array aVars a_: ;
>
>  length varname $32;
>
>  retain aBase;
>  array aMap [1000] _temporary_;
>
>  if _n_ = 1 then do;
>    * determine intermediate mapping array;
>    * tells us which qtr belongs to which a_* variable;
>    aBase = intnx ('qtr', '01jan1960'd, 0);
>    do _i_ = lbound(aVars) to hbound(aVars);
>      call vname (aVars(_i_), varname);
>      qtr = input (substr(varname,3),??yyq6.);
>      if qtr ne . then do;
>        qtrIndex = intck ('qtr', aBase, qtr);
>        * range checking could go here;
>        aMap [qtrIndex] = _i_;
>      end;
>    end;
>  end;
>
>  qtr = input (n,??yyq6.);
>  if qtr then do;
>    qtrIndex = intck ('qtr', aBase, qtr);
>    * range checking could go here;
>    a_new = aVars[aMap[qtrIndex]];
>  end;
>run;

<sasl:code>
proc print data=faux(obs=3);
  var row n a_new a_1996q3 a_1999q2 a_2003q1;
run;
/* on lst
 Obs    row      n       a_new    a_1996Q3    a_1999Q2    a_2003Q1

   1     1     1996Q3      .         843         638         574
   2     2     1999Q2      .         862         359         330
   3     3     2003Q1      .          44         893         540
*/

/* slow but works. not a wallpaper code, either.
by chang y chung 2004-01-16 */
%macro new_a(obs);
  %local dsid rc;
  %let dsid = %sysfunc(open(work.faux));
  %let rc = %sysfunc(fetchobs(&dsid., &obs.));
  %*;%sysfunc(getvarn(&dsid.,%sysfunc(varnum(&dsid.,a_&n.))))
  %let rc =%sysfunc(close(&dsid.));
%mend;
data two;
  set faux(obs=3);
  call symput('n', n);
  new_a = input(resolve('%new_a(' || put(_n_,best.) || ')'),best.);
  put n= new_a=;
run;
/* on log
n=1996Q3 new_a=843
n=1999Q2 new_a=359
n=2003Q1 new_a=540
*/
</sasl:code>