While the Fisher-Yates shuffle sounds like 1920′s dance move, it is the standard method for shuffling larger arrays of data.
The below operates like a simple Unix filter taking an array of data (separated by newlines) and returning a quickly sorted output.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | #!/usr/bin/perl # Usage: cat file | shuffle # From: http://hash-bang.net/2009/04/shuffling-shell-inputshuffling-shell-input/ # Return a shuffled version of the input stream # Author: Matt Carter <m@ttcarter.com> sub fisher_yates_shuffle { my $array = shift; my $i; for ($i = @$array; --$i; ) { my $j = int rand ($i+1); next if $i == $j; @$array[$i,$j] = @$array[$j,$i]; } } while(<>) { chomp; push @input, $_; } &fisher_yates_shuffle(\@input); print join("\n",@input); |
For example:
ls | shuffle |
Returns a randomized list of files in the current directory.
