1,a
2,b

##</code><code>##

1,2
a,b

##</code><code>##


1,2,3

4,5

##</code><code>##

,1,,4
,2,,5
,3,,

##</code><code>##

sub pivot
{
    my (@srcgrid) = @_;
    my $max_row = $#srcgrid;
    my $max_col = get_max_cols(@srcgrid);
    my @pivoted;
    for my $col (0..$max_col)
    {
        my @new_row;
        for my $row (0..$max_row)
        {
            my $value;
            if (defined $srcgrid[$row][$col])
            {
                $value = $srcgrid[$row][$col];
            }
            else
            {
                $value = '';
            }
            push @new_row,$value;
        }
        push @pivoted,\@new_row;
    }
    return @pivoted;
}
sub get_max_cols
{
    my (@grid) = @_;
    my $max= 0;
    for my $rowref (@grid)
    {
        my @row = @$rowref;
        if ($max < $#row)
        {
            $max = $#row;
        }
    }
    return $max;
}