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The answer's on your own hard drive, in the form of perldoc -q shuffle:
Found in /opt/perl/snap/lib/5.8.0/pods/perlfaq4.pod How do I shuffle an array randomly? If you either have Perl 5.8.0 or later installed, or if yo +u have Scalar-List-Utils 1.03 or later installed, you can say: use List::Util 'shuffle'; @shuffled = shuffle(@list); If not, you can use a Fisher-Yates shuffle. sub fisher_yates_shuffle { my $deck = shift; # $deck is a reference to an ar +ray my $i = @$deck; while ($i--) { my $j = int rand ($i+1); @$deck[$i,$j] = @$deck[$j,$i]; } } # shuffle my mpeg collection # my @mpeg = <audio/*/*.mp3>; fisher_yates_shuffle( \@mpeg ); # randomize @mpeg i +n place print @mpeg; Note that the above implementation shuffles an array in pl +ace, unlike the List::Util::shuffle() which takes a list and re +turns a new shuffled list. You've probably seen shuffling algorithms that work using splice, randomly picking another element to swap the curre +nt element with srand; @new = (); @old = 1 .. 10; # just a demo while (@old) { push(@new, splice(@old, rand @old, 1)); } This is bad because splice is already O(N), and since you +do it N times, you just invented a quadratic algorithm; that is, O(N**2). This does not scale, although Perl is so efficien +t that you probably won't notice this until you have rather largi +sh arrays.

-- Randal L. Schwartz, Perl hacker


In reply to •Re: Random array sorting by merlyn
in thread Random array sorting by kidd

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