Combine array of objects using keys

Question

I want to combine two arrays of objects. Let me give you an example:

Example:

// First array:

       $array1 = [
         { name => 'Joe', p_id => 1 },
         { name => 'Bob', p_id => 2 },
         { name => 'Sam', p_id => 4 }
        ]
// Second array:

       $array2 = [
         { id => 1, name => 'X'  },
         { id => 2, name => 'Y'  },
         { id => 4, name => 'Z'  }
        ]

Expected output:

 $output = [
  { name => 'Joe + X', id => 1 },
  { name => 'Bob + Y', id => 2 },
  { name => 'Sam + Z', id => 4 }
 ]

Goal:

I want the fastest possible way to combine the name property in the second array with the name property in the first array.

Note: The p_id property in the first array is the same as the id property in the second array.

What i try:

I've used nested loops that have a very low speed.

JesusValera · Accepted Answer · 2020-05-05 22:08:45Z

1

array_map is the solution!

Given:

$first = [
    { name => 'Joe', p_id => 1 },
    { name => 'Bob', p_id => 2 },
    { name => 'Sam', p_id => 4 },
];

$second = [
    { id => 1, name => 'X' },
    { id => 2, name => 'Y' },
    { id => 4, name => 'Z' },
];

The solution is just simply:

$result = array_map(
    static function (\stdClass $first, \stdClass $second): array {
        return [
            'name' => $first->name . ' + ' . $second->name,
            'id' => $first->p_id,
        ];
    },
    $first, $second
);

PS: I assume the objects are \stdClass, replace it by the correct one.

edited May 5, 2020 at 22:08

answered May 5, 2020 at 21:46

JesusValera

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Comments

ProtectedHector · Accepted Answer · 2020-05-05 23:31:36Z

Here is a solution for when the ids of the elements inside the array are not in order. Notice that I have changed the order of $array1. Just a bit better than the regular nested loops, on the loop of the $array2 it will remove the "found" elements to improve speed of the next loop.

From:

// First array:
$array1 = [
    (object) ['name' => 'Joe', 'p_id' => 1],
    (object) ['name' => 'Sam', 'p_id' => 4],
    (object) ['name' => 'Bob', 'p_id' => 2],
];

// Second array:
$array2 = [
    (object) ['id' => 1, 'name' => 'X'],
    (object) ['id' => 2, 'name' => 'Y'],
    (object) ['id' => 4, 'name' => 'Z'],
];

Solution:

$result = [];
foreach ($array1 as $array1Element) {
  for ($i=0;$i<count($array2);$i++) {
    if ($array1Element->p_id === $array2[$i]->id) {
      $array2[$i]->name = $array1Element->name . ' + ' . $array2[$i]->name;

      $result[] = $array2[$i];
      unset($array2[$i]);
      $array2 = array_values($array2);
      break;
  }
 }
}

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