hotshot has asked for the wisdom of the Perl Monks concerning the following question:

hello my friends!

I have the following function for sorting hash by it's values:
sub sortHash {

  my $hash = shift;

  my @keys = sort {
    @a = split(/[,-]/, $hash->{$a});
    @b = split(/[,-]/, $hash->{$b});
    $a[0] cmp $b[0] || $a[1] <=> $b[1] } keys(%{$hash});

  return \@keys;
}

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the functions works for hashes like:
my %hash = (
            '2.2.2.2' => 'nfs,1',
            '6.6.6.6' => 'afp-0',
            '3.3.3.3' => 'nfs-0',
            '4.4.4.4' => 'cifs,1',
            '1.1.1.1' => 'cifs,0',
           );

[download]
the function return the keys sorted by the values, for the above hash it will return:
my $array = &sortHash(\%hash);
print Dumper($array);

# will print
$VAR = [
        '6.6.6.6',
        '1.1.1.1',
        '4.4.4.4',
        '3.3.3.3',
        '2.2.2.2',
       ];

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The problem is that the values in the hash not always contain the index, and I get an use of Uninitialize value in numeric ....
Is there a way to chech for existence somehow in the sort function?

Hotshot

Replies are listed 'Best First'.
Re: sort by hash with existence check
by fruiture (Curate) on Nov 13, 2002 at 11:17 UTC

    First, you really want to use Schwartzian Transform and of course you can check for existence, in this case you check for defined()ness and you must specify the behaviuor: is 'nis-1' greater than 'nis' or less than or what? I assume 'nis-1' and 'nis' must be equal

    sub sortHash {
    my $hash = shift;

    [
       map  { $_->[0] }
       sort { $a->[1] cmp $b->[1] or
              defined( $a->[2] ) and
              defined( $b->[2] ) and
              $a->[2] <=> $b->[2]
       }
       map { [ $_ , split /[-,]/ ] }
       keys %$hash
   ]
}

    [download]
    --
    http://fruiture.de
[reply]
[d/l]
Re: sort by hash with existence check
by jdporter (Paladin) on Nov 14, 2002 at 05:33 UTC
[reply]
[d/l]

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