Insert hash array into an element in another hash array

Question

I am looking for a solution in how to implement a hash array (with keys & values), and insert it (push it) into another hash array, in an uninstantiated element; for example:

$variable1 = {

          0 => {
                          'Mathematics' => 82,
                          'Art' => 99,
                          'Literature' => 88
                        },
          1 => {
                         'Mathematics' => 97,
                         'Literature' => 67
                       }
        };


$variable2 = { 'Biology' => 47, 'Theology' => 87 };

...

Where the first variable1 index is iterated chronologically as a counter 0, 1, 2, 3 ... n

Therefore final variable1 should be...

$variable1 = {

          0 => {
                          'Mathematics' => 82,
                          'Art' => 99,
                          'Literature' => 88
                        },
          1 => {
                         'Mathematics' => 97,
                         'Literature' => 67
                       }

          2 => {
                         'Biology' => 47, 
                         'Theology' => 87

                       } 


        };

ysth · Accepted Answer · 2014-12-23 20:23:23Z

2

Why are you using a hash as the outer structure? If it were an array, it would just be:

$variable1 = [
    {
        'Mathematics' => 82,
        'Art' => 99,
        'Literature' => 88
    },
    {
        'Mathematics' => 97,
        'Literature' => 67
    }
];

$variable2 = { 'Biology' => 47, 'Theology' => 87 };

push @$variable1, $variable2;

Or if you want to push a copy (so that changes to $variable1->[2] don't affect $variable2),

push @$variable1, { %$variable2 };

With the structure you have, you'd have to do something like:

# assuming numbers are always sequential and start at 0
$variable1->{ keys %$variable1 } = $variable2;

# or if not
my $max_index = List::Util::max( keys %$variable1 ) // -1;
$variable1->{ $max_index+1 } = $variable2;

answered Dec 23, 2014 at 20:23

ysth

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mpapec · Accepted Answer · 2014-12-23 20:26:53Z

1

Since your keys are numeric, and you want to push new elements into structure, array of hashes is more natural to hold your data,

use strict;
use warnings;
use Data::Dumper;

my @variable1 = (
  {
    'Mathematics' => 82,
    'Art' => 99,
    'Literature' => 88
  },
  {
    'Mathematics' => 97,
    'Literature' => 67
  }
);


my $variable2 = { 'Biology' => 47, 'Theology' => 87 };

push @variable1, $variable2;

print Dumper \@variable1;

output

$VAR1 = [
      {
        'Art' => 99,
        'Literature' => 88,
        'Mathematics' => 82
      },
      {
        'Literature' => 67,
        'Mathematics' => 97
      },
      {
        'Biology' => 47,
        'Theology' => 87
      }
    ];

edited Dec 23, 2014 at 20:26

answered Dec 23, 2014 at 20:18

mpapec

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