in reply to Re^2: Sort the file names a list
in thread Sort the file names a list

ikegami++! I'd seen the GRT discussed, but never tried it myself. I guess I never thought enough about it, and my first-glance assessment was that memoization was faster. That'll teach me to make assumptions without testing!

Oh, and I saw the memoization technique called the "Orcish (or-cache) maneuver" in Perl Underground 2 (credit japhy).

$,=' ';$\=',';$_=[qw,Just another Perl hacker,];print@$_;

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Re^4: Sort the file names a list
by ikegami (Patriarch) on Aug 31, 2009 at 16:50 UTC
    I had a bug. Fixing it affected the times. You'll note that your solution actually slows down the sorting.
[reply]

      I thought that it might, for a small set of inputs. The overhead of creating and populating the hash, as well as assignments to two new lexicals would only be overcome with a significantly larger data set.

      I wonder, though. Yep. Changing it to this:

      {
my %cache;
sub memoized {
    ( $cache{$a} ||= substr($a, -(19+20), 19) )
    cmp ( $cache{$b} ||= substr($b, -(19+20), 19) );
}
}

      [download]

      gives a slight increase in speed (but my benchmarks are varying wildly right now. Maintaining ranking, but % differences are all over the board.)

                  Rate       st memoized    naive      grt
st       10281/s       --      -6%     -51%     -54%
memoized 10930/s       6%       --     -48%     -51%
naive    20942/s     104%      92%       --      -5%
grt      22143/s     115%     103%       6%       --

      [download]
      $,=' ';$\=',';$_=[qw,Just another Perl hacker,];print@$_;
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