How to restructure hash of hashes of hashes?

Question

I have a hash of hash of hash as

hash_1 =>{
           hash_2=>{
               a1 => {           
                      1 => m,
                      2 => x,
                      3 => n
                     },
               a2 =>  {
                      1 => a,
                      2 => x,
                      3 => b
                      },
                a3 =>  {
                      1 => c,
                      2 => y,
                      3 => d
                      },
                a4 =>  {
                      1 => i,
                      2 => y,
                      3 => j
                      },
             },
         };

Now I want to delete the key "hash_2" and and add new keys in place of "hash_2" which depends on the value of the key "2" inside each hashes a1, a2, a3... So, like here we have two different values for the key "2" : x and y. So I want this values to be in place of the key of the first hash "hash_2" and create a new hash map altogether. So end result should be :

  hash_1 =>{
           x=>{
               a1 => {           
                      1 => m,
                      2 => x,
                      3 => n
                     },
               a2 =>  {
                      1 => a,
                      2 => x,
                      3 => b
                      },
              },
            y => {
                a3 =>  {
                      1 => c,
                      2 => y,
                      3 => d
                      },
                a4 =>  {
                      1 => i,
                      2 => y,
                      3 => j
                      },
             },
         };

I checked How to replace a Perl hash key? but could not get how to make a value of a key as a key. I tried deleting the hash_2 but was not successful(using the delete keyword). Thanks.

Answer 1

Like this, perhaps?

use strict;
use warnings 'all';

use Data::Dump;

my $hash_1 = {
  hash_2 => {
    a1 => { 1 => "m", 2 => "x", 3 => "n" },
    a2 => { 1 => "a", 2 => "x", 3 => "b" },
    a3 => { 1 => "c", 2 => "y", 3 => "d" },
    a4 => { 1 => "i", 2 => "y", 3 => "j" },
  }
};

{
    my $data = delete $hash_1->{hash_2};

    for my $key ( keys %$data ) {
        my $item = $data->{$key};
        $hash_1->{ $item->{2} }{ $key } = $item;
    }
}

dd $hash_1;

output

{
  x => {
         a1 => { 1 => "m", 2 => "x", 3 => "n" },
         a2 => { 1 => "a", 2 => "x", 3 => "b" },
       },
  y => {
         a3 => { 1 => "c", 2 => "y", 3 => "d" },
         a4 => { 1 => "i", 2 => "y", 3 => "j" },
       },
}