The hash test seems a little unfair. It is the only one where you construct the data structure before testing it.

If you construct the hash before testing the results are somewhat different

I used the following, a slight change from your program

Assuming that you can use a hash table elsewhere in the program (and why not?) hash tables appear to make more sense when looked at this way. I cannot see any use for dynamically creating a hash table just for one search and, if you are going to search a hash you may as well structure your data into a hash.

Of course there are exceptions to this, there are exceptions to everything in the perl world (TIMTOWTDI)

anyway, the data: 

  use Benchmark;
  use strict;

  # Times array searches.  Assumes search element is in the
  # dead center of the array

  my $x;
  my @array;
  my %hash;

  for (10, 50, 100, 500, 1000, 5000)
  {
      @array = 1 .. $_;
      $x = $_ / 2;
      $hash{$_}++ for @array;

      print "Array size is $_\n";

      timethese(5000, {
          'grep' => \&grep_test,
          hash => \&hash_test,
          manual => \&manual_test
      });
  }

  sub grep_test
  {
      return 1 if grep { $x == $_ } @array;
  }

  sub hash_test
  {
      return 1 if $hash{$x};
  }

  sub manual_test
  {
      for (@array) { return 1 if $x == $_ }
  } 


Array size is 10
Benchmark: timing 5000 iterations of grep, hash, manual...
      grep:  0 wallclock secs ( 0.03 usr +  0.00 sys =  0.03 CPU)
            (warning: too few iterations for a reliable count)
      hash:  0 wallclock secs ( 0.00 usr +  0.00 sys =  0.00 CPU)
            (warning: too few iterations for a reliable count)
    manual:  0 wallclock secs ( 0.04 usr +  0.00 sys =  0.04 CPU)
            (warning: too few iterations for a reliable count)
Array size is 50
Benchmark: timing 5000 iterations of grep, hash, manual...
      grep:  0 wallclock secs ( 0.15 usr +  0.00 sys =  0.15 CPU)
            (warning: too few iterations for a reliable count)
      hash:  0 wallclock secs ( 0.01 usr +  0.00 sys =  0.01 CPU)
            (warning: too few iterations for a reliable count)
    manual:  0 wallclock secs ( 0.11 usr +  0.00 sys =  0.11 CPU)
            (warning: too few iterations for a reliable count)
Array size is 100
Benchmark: timing 5000 iterations of grep, hash, manual...
      grep:  0 wallclock secs ( 0.27 usr +  0.00 sys =  0.27 CPU)
            (warning: too few iterations for a reliable count)
      hash:  0 wallclock secs ( 0.02 usr +  0.00 sys =  0.02 CPU)
            (warning: too few iterations for a reliable count)
    manual:  1 wallclock secs ( 0.20 usr +  0.00 sys =  0.20 CPU)
            (warning: too few iterations for a reliable count)
Array size is 500
Benchmark: timing 5000 iterations of grep, hash, manual...
      grep:  1 wallclock secs ( 1.39 usr +  0.00 sys =  1.39 CPU)
      hash:  0 wallclock secs (-0.00 usr +  0.00 sys = -0.00 CPU)
            (warning: too few iterations for a reliable count)
    manual:  1 wallclock secs ( 0.90 usr +  0.00 sys =  0.90 CPU)
Array size is 1000
Benchmark: timing 5000 iterations of grep, hash, manual...
      grep:  3 wallclock secs ( 2.79 usr +  0.00 sys =  2.79 CPU)
      hash:  0 wallclock secs ( 0.02 usr +  0.00 sys =  0.02 CPU)
            (warning: too few iterations for a reliable count)
    manual:  2 wallclock secs ( 1.77 usr +  0.00 sys =  1.77 CPU)
Array size is 5000
Benchmark: timing 5000 iterations of grep, hash, manual...
      grep: 15 wallclock secs (15.39 usr +  0.00 sys = 15.39 CPU)
      hash:  0 wallclock secs ( 0.01 usr +  0.00 sys =  0.01 CPU)
            (warning: too few iterations for a reliable count)
    manual: 10 wallclock secs ( 9.03 usr +  0.05 sys =  9.08 CPU)

[download]

In reply to RE: Doesn't anyone do their homework anymore? by Caillte
in thread better way to find list members? by jptxs

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.