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How to Merge PHP Arrays with Shared Keys Using `array_map`?

Mary-Kate Olsen
Mary-Kate OlsenOriginal
2024-11-01 07:21:30300browse

How to Merge PHP Arrays with Shared Keys Using  `array_map`?

PHP Array Merge on Same Key: A Solution Using array_map

In PHP, merging arrays can be challenging when the arrays share common keys. Let's address this problem with a solution that leverages the array_map function.

Objective:
Merge two arrays, $array1 and $array2, based on shared keys (e.g., "Camera1", "Camera2"), and ensure the merged result maintains the desired structure.

Solution:
array_map offers a way to iterate over multiple arrays simultaneously, applying a callback function to each element. Here's how we can use it:

<code class="php">$array1 = [
    ["Camera1" => "192.168.101.71"],
    ["Camera2" => "192.168.101.72"],
    ["Camera3" => "192.168.101.74"]
];

$array2 = [
    ["Camera1" => "VT"],
    ["Camera2" => "UB"],
    ["Camera3" => "FX"]
];

$results = [];

array_map(function($a, $b) use (&$results) {
    // Get the key for both arrays
    $key = current(array_keys($a));
    $a[$key] = ['ip' => $a[$key]];
    $key = current(array_keys($b));
    $b[$key] = ['name' => $b[$key]];
    
    $results += array_merge_recursive($a, $b);
}, $array1, $array2);</code>

How It Works:

  • The callback function iterates through each element in $array1 and $array2.
  • For each element, it retrieves the key (e.g., "Camera1") and modifies the value accordingly, adding new keys ('ip' and 'name') to ensure consistent array structure.
  • The modified elements are merged using array_merge_recursive and stored in $results.
  • The resulting array combines both element values for each shared key, retaining the modified structure.

Output:

var_dump($results);

Will produce the following output:

<code class="php">array (size=3)
  'Camera1' => 
    array (size=2)
      'ip' => string '192.168.101.71' (length=14)
      'name' => string 'VT' (length=2)
  'Camera2' => 
    array (size=2)
      'ip' => string '192.168.101.72' (length=14)
      'name' => string 'UB' (length=2)
  'Camera3' => 
    array (size=2)
      'ip' => string '192.168.101.74' (length=14)
      'name' => string 'FX' (length=2)</code>

This solution effectively merges the two arrays while preserving the shared keys and ensuring the desired array structure.

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