#!/usr/bin/perl -w


use strict;


my %hash = (

'c' =>
{ 'e' => '54.9503577512828',
           '21' => '40.4544882398113',
           '7' => '13.665886711539',
           '17' => '26.3268082750993',
           '2' => '16.4348644122811',
           '22' => '35.2357587506792',
           '1' => '29.5471128362965',
           '18' => '28.8861232027377',
           '23' => '19.3437720284897',

         },
'd'  =>
        {

           '11' => '26.7647206436788',
           '21' => '19.4128184125387',
           '7' => '6.89345884629317',
           '17' => '12.7682648883531',
           '2' => '8.44015343941174',
           '22' => '16.9085166076037',
           '1' => '15.1739716114483',
           '18' => '13.9203445318945',

         },
'b' =>
        {
           '11' => '11.5303855045498',
           '21' => '9.28718107649433',
           '7' => '2.50040155572952',
           '17' => '5.93010343000324',
           '2' => '2.86098737229312',

         }

);

foreach my $k1 (sort keys %hash){
   print "\n-> $k1\n";
   my $count = 0;
   foreach my $k2 (sort {$hash{$k1}->{$b} <=> $hash{$k1}->{$a} } keys 
+%{$hash{$k1}} ){
        print "--> $k2: $hash{$k1}->{$k2}\n";
        last if $count++ > 0;
   }
}
[download]

Thanks a million gulden. Your script results are exactly what I want.
I was introduced to perl only a week ago so still learning as I code more.

Once again Thanks all for your help. Very much appreciated
Stan

If you want to sort "numbers" instead of "strings" for the first level keys of the hash, then replace

 foreach my $k1 (sort keys %hash){
[download]

with

 foreach my $k1 (sort {$a <=> $b} keys %hash){
[download]

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

# a HoH

my %people = ("Fred Jones" => {"AGE" =>45, "SALARY" => 90000},
              "Joe Smith"  => {"AGE" =>32, "SALARY" => 36400},
              "Mary Arne"  => {"AGE" =>29, "SALARY" => 66122},
              "Ted Carney" => {"AGE" =>56, "SALARY" => 100000},
             );


foreach my $key (sort keys %people) 
{
    print "  $key $people{$key}->{'AGE'} $people{$key}->{'SALARY'}\n";
+  
}

print "\nThis is the version using a hash slice\n";

foreach my $key (sort keys %people) 
{
    print "  $key @{$people{$key}}{('AGE', 'SALARY')} \n";
}

__END__
Prints:
  Fred Jones 45 90000
  Joe Smith 32 36400
  Mary Arne 29 66122
  Ted Carney 56 100000

This is the version using a hash slice
  Fred Jones 45 90000 
  Joe Smith 32 36400 
  Mary Arne 29 66122 
  Ted Carney 56 100000
[download]

Well, by definitions hashes are unordered collections. You could e.g. get an ordered list/array of key/value pairs or whatever, but they won't be hashes. Or you could use Tie::Hash::Indexed or Tie::IxHash to get ordered hashes.

Regarding your questions, I hope you can re-phrase them.

-- Kirill

Ok let me rephrase. Here is my hash


%hash{
a => {doc1=>'2.0',
      doc2=>'4.5',
      doc7=>'3.0'
     },
b => { doc2 => '3.5',
       doc10 => '6.5',
       doc7 => '11.4',
       doc20 => '0.5'
     }
}
[download]


Now for 'a' I need to retrieve top 2 doc with highest value.
In this case it will be 'doc2' and 'doc7'
In case of 'b' it will be 'doc7' and 'doc10'
Number of docs will differ in 'a' and 'b'.
Does this clarify my question

I've run my script and the result was:

-> a
--> doc2: 4.5
--> doc7: 3.0

-> b
--> doc7: 11.4
--> doc10: 6.5

For example, given

use Data::Dumper;

my %hash = (
    9 => {
        11 => '54.9503577512828',
        21 => '40.4544882398113',
    },
    4 => {
        11 => '26.7647206436788',
        21 => '19.4128184125387',
    }
);
[download]

print Dumper %hash yields

$VAR1 = '4';
$VAR2 = {
          '11' => '26.7647206436788',
          '21' => '19.4128184125387'
        };
$VAR3 = '9';
$VAR4 = {
          '11' => '54.9503577512828',
          '21' => '40.4544882398113'
        };
[download]

but print Dumper \%hash (note the backslash) produces

$VAR1 = {
          '4' => {
                   '11' => '26.7647206436788',
                   '21' => '19.4128184125387'
                 },
          '9' => {
                   '11' => '54.9503577512828',
                   '21' => '40.4544882398113'
                 }
        };
[download]