php - strange array puzzle

Question

I have an array that looks like this:

$array = array(
[0] => array( [key] => val1 ),
[1] => array( [key] => val2 ),
[2] => array( [key] => val3 ),
...
)

I want to make it look like this:

$array = array(
[0] => val1 ),
[1] => val2 ),
[2] => val3 ),
...
)

Obviously I could just loop through the array and construct a new array, but is there any more efficient way to do what I'm describing?

Answer 1

Powered by trivial standard library knowledge:

$new_array = array_map(function($i) {
    return $i['key'];
}, $array);

or if you're using php >= 5.5

$new_array = array_column($array, 'key');

or if the key name is not known and you just want to make 2d array into 1d:

$new_array = call_user_func_array('array_merge', array_map('array_values', $array));

References:

• http://php.net/manual/en/function.array-column.php
• http://php.net/array_map
• http://php.net/array_merge
• http://php.net/array_values
• http://php.net/call_user_func_array

Answer 2

Powered by this answer:

<?php
$array = array(
  0 => array( 'key' => 'val1' ),
  1 => array( 'key' => 'val2' ),
  2 => array( 'key' => 'val3' ),
);
$new_array = array();
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($array));
foreach($it as $v) {
  $new_array[] = $v;
}
print_r($new_array);

Demo