As tangent has already explained in his post, Sort::Key::Natural breaks the string at the boundaries between alphabetic and number groups. So for instance, P007b_Yum is equivalent to P_7_b_Yum.

If you want alphanumeric groups to remain unbroken, you will have to change the sorting-key generation algorithm.

This probably does what you want (untested): 

use Sort::Key qw(keysort);

sub mknkey {
    my $n = shift;
    $n =~ s/^0+//;
    my $len = length $n;
    my $nines = int ($len / 9);
    my $rest = $len - 9 * $nines;
    ('9' x $nines) . $rest . $n;
}

sub mknatkey {
    my $nat = @_ ? shift : $_;
    $nat =~ s/(\d+)/mknkey($1)/ge;
    $nat;
}

my @sorted = keysort { mknatkey($_) } @data;

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In reply to Re: Sort::Key::Natural sorting discrepancy by salva
in thread Sort::Key::Natural sorting discrepancy by cr8josh

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