Question

I’ve just started diving in to the crazy world that is perl and have come across a problem that I cannot seem to wrap my head around. Specifically I need to be able to convert from one hash structure to another, that uses the keys/values as the new hashes keys/values.

An example:

Input hash:

    my %original_hash = (
    first_key => {  some_key => "apples",
                    another_key => "chips",
                    #potentially more here
                 },
     second_key => {  more_of_same => "dogs", 
                      its_another => "cats",
                      #potentially more here 
                   }
      );

Output hash:

my %final_hash = ( 
   some_key => { 
                    apples => { 
                                more_of_same => "dogs", 
                                its_another => "cats", 
                              } 
               } ,
   another_key => { 
                    chips => { 
                                more_of_same => "dogs", 
                                its_another => "cats",
                              } 
                  } 

);

And yes I do want the second_key’s data repeated in the final_hash, as there will be an array of the original_hashes that are inputted. The first element becomes the base-case, and all other elements may append or remove from that list.

If anyone has any suggestions on how to go about doing this that would be greatly appreciated!

Answer 1

Here is another way

my %final_hash;

my %tmp = %{$original_hash{first_key}}; 
my $val = $original_hash{second_key};

while ( my ($k,$v) = each %tmp) {
    $final_hash{$k} =  { $v => $val };
}


print Dumper (\%final_hash);