array_replace_recursive() without creation of keys

Question

In PHP, array_replace_recursive() does two things according to the documentation:

If a key from the first array exists in the second array, its value will be replaced by the value from the second array.
If the key exists in the second array, and not the first, it will be created in the first array.

Is there an alternative that only does the replacement, and doesn't create new keys?

For example:

$array = [
  'apple' => TRUE,
  'pear' => TRUE,
  'basket' => [
    'banana' => TRUE,
  ],
  'punnet' => [
    'strawberry' => TRUE,
  ],
];

$replacement = [
  'banana' => [
    'REPLACEMENT!'
  ],
];

The result should be:

$array = [
  'apple' => TRUE,
  'pear' => TRUE,
  'basket' => [
    'banana' => [
      'REPLACEMENT!'
    ],
  ],
  'punnet' => [
    'strawberry' => TRUE,
  ],
];

Could you show a specific example of what you want to achieve. — Nigel Ren
– Nigel Ren, Commented Mar 9, 2021 at 17:38
array_replace_recursive() doesn't do what I need. That's not the same as not understanding it. Also, I'd argue that what array_replace_recursive() does is not 'replace'. — joachim
– joachim, Commented Mar 10, 2021 at 15:49
@joachim Nope, it does what it says. Keys need to match between the first array and second array for replacement. See this link to understand the difference between your replacement and the one in the link. sandbox.onlinephpfunctions.com/code/… — mighty_dev
– mighty_dev, Commented Mar 10, 2021 at 17:58

Prince Dorcis · Accepted Answer · 2021-03-09 19:13:54Z

0

You will need to use array_intersect_key() to create an array that contains only the keys that are in the two arrays, then you can merge.

$array1 = [
    'a' => 1,
    'b' => 2,
    'c' => 3,
    'd' => 4,
];

$array2 = [
    'b' => 14,
    'c' => 70,
    'f' => 5,
];

// $array2 has to be the first arguments for $inter to have its value instead of the value of $array1
$inter = array_intersect_key($array2, $array1);

$merged = array_replace_recursive($array1, $inter);

// Merged will be: 
[
    'a' => 1,
    'b' => 14,
    'c' => 70,
    'd' => 4,
];

array_intersect_key

EDIT For this to work recursively, you can use this function found here

/** 
* Recursively computes the intersection of arrays using keys for comparison.
* 
* @param   array $array1 The array with master keys to check.
* @param   array $array2 An array to compare keys against.
* @return  array associative array containing all the entries of array1 which have keys that are present in array2.
**/
function array_intersect_key_recursive(array $array1, array $array2) {
    $array1 = array_intersect_key($array1, $array2);

    foreach ($array1 as $key => &$value) {
        if (is_array($value) && is_array($array2[$key])) {
            $value = array_intersect_key_recursive($value, $array2[$key]);
        }
    }

    return $array1;
}

edited Mar 9, 2021 at 19:13

answered Mar 9, 2021 at 18:12

Prince Dorcis

1,0559 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

mighty_dev Over a year ago

It needs to be recursive, not just the first layer.

Prince Dorcis Over a year ago

Ok. PHP does not have that directly. We need to implemented it. Hopefully it has already been done. I've edited the answer.

joachim Over a year ago

I'm not sure intersection is the right thing to do here. I've added an example to the question.

mickmackusa Over a year ago

The haystack has banana is inside basket; the needle has banana on the first level -- neither of these snippets will work as required.

joachim · Accepted Answer · 2021-03-11 08:54:07Z

0

This does what I needed:

array_walk_recursive($array, function(&$value, $key, $replacements) {
  if (isset($replacements[$key])) {
    $value = $replacements[$key];
  }
}, ['replace' => 'replacement']);

answered Mar 11, 2021 at 8:54

joachim

31.4k13 gold badges46 silver badges51 bronze badges

1 Comment

mickmackusa Over a year ago

This unexplained answer works with the sample data because the sought value/replacement is on a leaf-node.

Collectives™ on Stack Overflow

array_replace_recursive() without creation of keys

2 Answers 2

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related