So, essentially you want to sample w/o replacement. If you don't want to make a complete copy of your array (because it is very large or whatever), you can use the random_permuted_index() method from Math::Random. Another benefit to this module is that (as I understand it), the randomization is 'more random' than for rand; however, it may not be an issue in your case. Also, if you want to keep grabbing two at a time over and over, try splice regardless of how you do your sampling. (Splice is like shift/pop on 'roids.) Here is an example: 
#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;
use Math::Random;

my @array = qw( cat dog shark frog chimp seahorse );
my @permuted_index = random_permuted_index( scalar(@array) );

print "Here is your entire set:\n";
print Dumper @array;
print "Here is a random pick of two:\n";
print Dumper @array[ splice( @permuted_index, 0, 2 ) ];
print "And another two (unique from 1st two):\n";
print Dumper @array[ splice( @permuted_index, 0, 2 ) ];
print "And the final two:\n";
print Dumper @array[ splice( @permuted_index, 0, 2 ) ];

[download]

Sample output:

Here is your entire set:
$VAR1 = 'cat';
$VAR2 = 'dog';
$VAR3 = 'shark';
$VAR4 = 'frog';
$VAR5 = 'chimp';
$VAR6 = 'seahorse';
Here is a random pick of two:
$VAR1 = 'dog';
$VAR2 = 'shark';
And another two (unique from 1st two):
$VAR1 = 'seahorse';
$VAR2 = 'frog';
And the final two:
$VAR1 = 'cat';
$VAR2 = 'chimp';

[download]

In reply to Re: biased random number picking by frozenwithjoy
in thread biased random number picking by Anonymous Monk

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.