Re: Counting Variations of Key in a Hash

[polettix]

davidrw basically gave the core answer in his reply. As I suggested in the answer you cite, you should probably try to think a basic working algorithm even if it's not optimised and it requires more passes to be executed.

If this is exactly what you need, davidrw's answer will not suffice, of course. In this case, instead of trying to do all the work in one multi-nested loop (whatever the nesting depth), I'd stick to do one thing at a time and proceed by steps. In this case, you should track the variations together with the other stuff:

#!/usr/bin/perl
use strict;
use warnings;
use Storable qw( freeze thaw );
use Data::Dumper;

my %bighash = (

 'Arizona'=> {
              'ZOO_1' => [ '5','HIPPO1', ['feat1'],['feat2']],
              'ZOO_2' => [ '10','HIPPO2',['feat1'],['feat2']],
              'ZOO_3' => [ '2', 'PUMA1', ['feat1'],['feat2']],
              'ZOO_5' => [ '13', 'PUMA2',['feat1'],['feat2']],
            },
'Indiana' => {
              'ZOO_2' => [ '10','HIPPO3',  ['feat1'],['feat2']],
              'ZOO_9' => [ '25','ZEBRA1',  ['feat1'],['feat2']],
              'ZOO_5' => [ '13','MONKEY1', ['feat1'],['feat2']],
              'ZOO_6' => [ '23','ZEBRA2',  ['feat1'],['feat2']],
              'ZOO_3' => [ '2', 'PUMA3',   ['feat1'],['feat2']],
              'ZOO_5' => [ '1', 'PUMA4',   ['feat1'],['feat2']],
             },
'Nevada' => {
             'ZOO_3' => [ '3', 'HIPPO4',  ['feat1'],['feat2']], 
             'ZOO_7' => [ '11', 'HIPPO5', ['feat1'],['feat2']], 
             'ZOO_4' => [ '21', 'LION1',  ['feat1'],['feat2']], 
             'ZOO_12' => [ '13','MONKEY2',['feat1'],['feat2']],
         },
      );

my %animals;
{ # Scope reduction, could be put inside a function :)
   my %tmp;
   while ( my ($state, $zoos) = each %bighash )   {
      while ( my ($zoo, $row) = each %$zoos ){
         my $animal = $row->[1];
         (my $root = $animal) =~ s/\d+$//;
     $tmp{$root}{variations}{$animal} = 1;
         push @{$tmp{$root}{data}{$state}}, $zoo;
      }
   }

   # Now we traverse %tmp to create the needed structure
   foreach my $href (values %tmp) {
      # Use freeze/thaw from Storable to do deep hash copying
      my $frozen = freeze($href->{data});
      $animals{$_} = thaw($frozen) foreach keys %{$href->{variations}}
   }
}

$Data::Dumper::Sortkeys = 1;
print Dumper \%animals ;

which gives

$VAR1 = {
          'HIPPO1' => {
                        'Arizona' => [
                                       'ZOO_1',
                                       'ZOO_2'
                                     ],
                        'Indiana' => [
                                       'ZOO_2'
                                     ],
                        'Nevada' => [
                                      'ZOO_7',
                                      'ZOO_3'
                                    ]
                      },
          'HIPPO2' => {
                        'Arizona' => [
                                       'ZOO_1',
                                       'ZOO_2'
                                     ],
                        'Indiana' => [
                                       'ZOO_2'
                                     ],
                        'Nevada' => [
                                      'ZOO_7',
                                      'ZOO_3'
                                    ]
                      },
          'HIPPO3' => {
                        'Arizona' => [
                                       'ZOO_1',
                                       'ZOO_2'
                                     ],
                        'Indiana' => [
                                       'ZOO_2'
                                     ],
                        'Nevada' => [
                                      'ZOO_7',
                                      'ZOO_3'
                                    ]
                      },
          'HIPPO4' => {
                        'Arizona' => [
                                       'ZOO_1',
                                       'ZOO_2'
                                     ],
                        'Indiana' => [
                                       'ZOO_2'
                                     ],
                        'Nevada' => [
                                      'ZOO_7',
                                      'ZOO_3'
                                    ]
                      },
          'HIPPO5' => {
                        'Arizona' => [
                                       'ZOO_1',
                                       'ZOO_2'
                                     ],
                        'Indiana' => [
                                       'ZOO_2'
                                     ],
                        'Nevada' => [
                                      'ZOO_7',
                                      'ZOO_3'
                                    ]
                      },
          'LION1' => {
                       'Nevada' => [
                                     'ZOO_4'
                                   ]
                     },
          'MONKEY2' => {
                         'Nevada' => [
                                       'ZOO_12'
                                     ]
                       },
          'PUMA1' => {
                       'Arizona' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ],
                       'Indiana' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ]
                     },
          'PUMA2' => {
                       'Arizona' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ],
                       'Indiana' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ]
                     },
          'PUMA3' => {
                       'Arizona' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ],
                       'Indiana' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ]
                     },
          'PUMA4' => {
                       'Arizona' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ],
                       'Indiana' => [
                                      'ZOO_5',
                                      'ZOO_3'
                                    ]
                     },
          'ZEBRA1' => {
                        'Indiana' => [
                                       'ZOO_9',
                                       'ZOO_6'
                                     ]
                      },
          'ZEBRA2' => {
                        'Indiana' => [
                                       'ZOO_9',
                                       'ZOO_6'
                                     ]
                      }
        };

You'll notice that I'm using Storable to do deep hash copying, but you can use other methods of course. If you can share the data between similar animals, you can get rid of this copying and do simply:

foreach my $href (values %tmp) {
   $animals{$_} = $href->{data} foreach keys %{$href->{variations}}
}

For some considerations about this deep (or shallow) copy stuff you can also start from this thread, and in particular from pelagic's answer.