Unzip, permute second list, rezip

permute.pl

#! perl

use List::Util qw(shuffle);
use Data::Dumper;

my @input = ( [ 'a', 1 ], [ 'b', 1 ], [ 'c', 2 ], [ 'd', 2 ] );

my @element_1s = map { $_->[0] } @input;
my @element_2s = map { $_->[1] } @input;

my @random_2s = shuffle @element_2s;

my @final;
for ( my $i = 0; $i < $#input + 1; $i++ ) {
    my $t = [ $element_1s[$i], $random_2s[$i] ];

    push @final, $t;
}

print Dumper @final;