Multidimensional indexed array to associative array depending on column value

arrays, multidimensional-array, php

Solution

The truth is php DOES offer a single, native function that allows you to replace the outer indexes with the values of a single column. The "magic" is in the 2nd parameter which tells php not to touch the subarray values when assigning the new keys.

Code: (Demo)

$indexed = [
    ['id' => 'john', 'name' => 'John', 'age' => 29],
    ['id' => 'peter', 'name' => 'Peter', 'age' => 30],
    ['id' => 'harry', 'name' => 'Harry', 'age' => 19],
];

var_export(array_column($indexed, null, 'id'));

Output:

array (
  'john' => 
  array (
    'id' => 'john',
    'name' => 'John',
    'age' => 29,
  ),
  'peter' => 
  array (
    'id' => 'peter',
    'name' => 'Peter',
    'age' => 30,
  ),
  'harry' => 
  array (
    'id' => 'harry',
    'name' => 'Harry',
    'age' => 19,
  ),
)

This even works on an array of objects. The end result is an array of objects with new, associative first-level keys. (Demo)

$indexed = [
    (object)['id' => 'john', 'name' => 'John', 'age' => 29],
    (object)['id' => 'peter', 'name' => 'Peter', 'age' => 30],
    (object)['id' => 'harry', 'name' => 'Harry', 'age' => 19],
];

var_export(array_column($indexed, null, 'id'));

Output:

array (
  'john' => 
  (object) array(
     'id' => 'john',
     'name' => 'John',
     'age' => 29,
  ),
  'peter' => 
  (object) array(
     'id' => 'peter',
     'name' => 'Peter',
     'age' => 30,
  ),
  'harry' => 
  (object) array(
     'id' => 'harry',
     'name' => 'Harry',
     'age' => 19,
  ),
)

Problem

I have a multidimensional indexed array. Each element is an associative array with an `id` column which is unique between elements (its value never repeats within the array). ``` [indexed] =>Array ( [0] => Array ( [id] => john [name] => John [age] => 29 ), [1] => Array ( [id] => peter [name] => Peter [age] => 30 ), [2] => Array ( [id] => harry [name] => Harry [age] => 19 ) ) ``` My goal is to convert this array into a multidimensional associative array, indexed by `id` values. ``` [indexed] =>Array ( [john] => Array ( [id] => john [name] => John [age] => 29 ), [peter] => Array ( [id] => peter [name] => Peter [age] => 30 ), [harry] => Array ( [id] => harry [name] => Harry [age] => 19 ) ) ``` My best attempt so far is to loop over array elements and manually create the final array. ``` $associative = array(); foreach($indexed as $key=>$val) $associative[$val['id']] = $val; ``` I think it's not the most elegant solution. Is it possible to obtain the same result with built-in (more efficient) functions?

Original source