PHP Loop through multi-dimensional array into new array

Question

I have a PHP array like this...

[level1] => Array
(
    [random475item] => Array
        (
            [attr1] => tester1
            [attr2] => tester2
            [attr3] => tester3
        )
    [random455item] => Array
        (
            [attr1] => tester1
            [attr2] => tester2
            [attr3] => tester3
        )
)

I am trying to get the values of the attr2 fields in a new array. I can specify a specific like this...

$newarray = array();
newarray [] = $array['level1']['random475item']['attr2'];
newarray [] = $array['level1']['random455item']['attr2'];

But is there a way to automate this as it could be 50 random items coming up and I don't want to have to keep adding them manually.

Answer 1

https://www.php.net/manual/en/function.array-column.php and the code below at https://3v4l.org/8j3ae

<?php 
$array = ['level1' => [
    'item1' => [
        'attr1' => 'test1',
        'attr2' => 'test2',
        'attr3' => 'test3'
    ],
    'item2' => [
        'attr1' => 'test4',
        'attr2' => 'test5',
        'attr3' => 'test6'
    ],
]];

$values = array_column($array['level1'], 'attr2');

var_dump($values);

creates

array(2) {
  [0]=>
  string(5) "test2"
  [1]=>
  string(5) "test5"
}

Answer 2

You can use array_map for that :

$array = ['level1' => [
    'item1' => [
        'attr1' => 'test1',
        'attr2' => 'test2',
        'attr3' => 'test3'
    ],
    'item2' => [
        'attr1' => 'test4',
        'attr2' => 'test5',
        'attr3' => 'test6'
    ],
]];

// parse every item
$values = array_map(function($item) {
    // for each item, return the value 'attr2'
    return $item['attr2'];
}, $array['level1']);

I have created a sandbox for you to try;

Answer 3

Use foreach statement will be solved your case

$newarray = array();
foreach($array['level1'] as $randomItemKey => $randomItemValue){
   $newarray[] = $randomItemValue['attr2'];
}

Answer 4

If the values can occur at any point in the array, you can use array_walk_recursive() which will loop through all of the values (only leaf nodes) and you can check if it is an attr2 element and add it into an output array...

$out = [];
array_walk_recursive($array, function ($data, $key ) use (&$out)    {
    if ( $key == "attr2" )  {
        $out[] = $data;
    }
});