#!/usr/bin/perl -w
use strict;

# transpose input.  won't align right if rows don't have 
# same # num of things, but then again Op's version will go
# pretty wacky with: 1 2 3 4
#                    a b c d e f

my @inAoA;
my @transposed_AoA;

while (<DATA>)
{
   chomp;      #not needed for \s, but here for \t option
   push(@inAoA,[split(/\s/,$_)]); #could be \t too
}

transpose_2d_array(\@inAoA, \@transposed_AoA);
dump_AoA (\@transposed_AoA);

sub transpose_2d_array
{
   my ($in_aref, $out_aref) = @_;
    
   foreach my $in_row (@$in_aref)
   { 
      my $new_row =0;
      foreach my $col_ele (@$in_row)
      {
         push (@{$out_aref->[$new_row]},$col_ele);
         $new_row++;
      }
   }   
}

sub dump_AoA   #with tabs between columns
{
   my $AoA_ref = shift;
   foreach my $aref (@$AoA_ref)
   {
       print join("\t",@$aref),"\n";
   }
}
=PrintOut of above code:
1	a
2	b
3	c
4	d
5	e
6	f
=cut

__DATA__
1 2 3 4 5 6
a b c d e f