Date:         Tue, 8 Feb 2011 16:22:21 -0500
Reply-To:     Chang Chung <chang_y_chung@HOTMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Chang Chung <chang_y_chung@HOTMAIL.COM>
Subject:      Re: Strip Function And Leading and Trailing Tab Chars
Comments: To: Toby Dunn <tobydunn@HOTMAIL.COM>

On Tue, 8 Feb 2011 20:20:30 +0000, toby dunn <tobydunn@HOTMAIL.COM> wrote:
...
>I'll preface this with much depends on ones data if you are looking to eek
the last ounce of speed and/or efficiency.
>However, the two RegEx solution is by in large the best all around
solution.
...
hi, toby,
Thanks for the Friedl reference. I get that the alternation (|) kills the
prx optimization. But this matters only when the overhead of making the
prxchange() function call is negligible compared to the savings you get
from prx optimization. I am not so sure if this is the case. Below is my
test code. In terms of real time, I get wildly different results each time
I run it, despite of the sasfile'ing. But I noticed that the cpu time is
always about twice as longer for data step toby than chang.
Cheers,
Chang

%let seed=1234;

data one;
   length s $200;
   do i = 1 to 1e6;
      do j = 1 to 200;
         if ranuni(&seed) < 0.05 then substr(s,j,1) = " ";
      end;
      output;
   end;
run;

sasfile work.one.data open;
   data chang;
      set one;
      s2 = prxchange('s/^\s+|\s+$//o', -1, s);
      keep s s2;
   run;
   data toby;
      set one;
      s3 = prxchange('s/^\s+//o', 1, s);
      s3 = prxchange('s/\s+$//o', 1, s3);
      keep s s3;
   run;
sasfile work.one.data close;

proc compare data=toby compare=chang(rename=(s2=s3));
run;
/* on log
 NOTE: No unequal values were found. All values compared are exactly equal.
*/