Re: Max value

[ameezys]

Thank you for the replies. Another question is, if b and c has the same value which is 3. how do I display both of it?

[hippo]

See the appropriate FAQ: How do I sort a hash (optionally by value instead of key)?

[tybalt89]

#!/usr/bin/perl

# https://perlmonks.org/?node_id=1232659

use strict;
use warnings;
use List::Util qw( reduce );

my %hashName = (a => 1, b => 3, c => 3);

sub allmax
  {
  reduce { $a->[-1] > $b->[-1] ? $a :
    $a->[-1] < $b->[-1] ? $b :
    [ @{$a}[0..@$a-2], @$b ] } @_;
  }

my $maxref = allmax( map [ $_, $hashName{$_} ], sort keys %hashName );

print "@$maxref\n";

Outputs:

b c 3

[AnomalousMonk]

[-@$a..-2] would have been slightly more obscure IMHO ;-)

[Marshall]

#!/usr/bin/perl
use strict;
use warnings;

my %hashName = (a => 1, b => 2, c => 3, d=>3);

#sort keys by descending order of their value
my @keys = sort {$hashName{$b} <=> $hashName{$a}} keys %hashName;

my $max = $hashName{$keys[0]};

while (my $key = shift @keys)
{
   last if ($hashName{$key} < $max);
   print "$key=>$hashName{$key}\n";
}
__END__
c=>3
d=>3

Update: I guess I should have added some comments to this post. There are very tricky and obtuse looking sort algorithms. Don't mistake "shorter code" or more "complex code" for "better code". When working with a hash of say <50 keys, my advice is to go with simple code. I start thinking about whipping out the "Perl nuclear weapons" when sort size gets above 1,000.

[rsFalse]

Another one variant:

use strict;
use warnings;

my %hash_name = ( a => 1, b => 2, c => 3, d => 3 );

my %keys_of_max;
my $key_of_max;
my $numeric_cmp_result;

    $numeric_cmp_result = defined $key_of_max
        ? ( eval join '<=>', map { $hash_name{ $_ } } $_, $key_of_max 
+)
        : 1
    xor $numeric_cmp_result > 0 and %keys_of_max = ( $key_of_max = $_ 
+=> 1 )
    xor ( $numeric_cmp_result or $keys_of_max{ $_ } = 1 )
        for keys %hash_name;

print sort keys %keys_of_max;

OUTPUT:

Useless use of logical xor in void context at perlmonks_Max_Value.pl l
+ine 26.
cd