PHP Add element to every sub array of multi dimension array

Question

I have an array that looks something like that

array(
     [0] => array(
               'id' => 1,
               'title' => 'title 1',
     ),
     [1] => array(
               'id' => 10,
               'title' => 'title 10',
     ),
     [2] => array(
               'id' => 11,
               'title' => 'title 11',
     ),
     [...]
);

I want to add an element to all the sub array. It's the same element i'm adding. so the new array will look like :

array(
     [0] => array(
               'id' => 1,
               'title' => 'title 1',
               'type'  => 'bag',
     ),
     [1] => array(
               'id' => 10,
               'title' => 'title 10',
               'type'  => 'bag',
     ),
     [2] => array(
               'id' => 11,
               'title' => 'title 11',
               'type'  => 'bag',
     ),
     [...]
);

Is there a way to do it without iterating on the the first array? It's gonna be a big array. I'm looking for the fastest way to do it.

Answer 1

Whatever speed one might hope to gain by using array_walk, is lost with function overhead. Since you stated in your comments that the array is a result of a db query, you can simply include the bag value in your result set by adding SELECT 'bag' AS 'type' to your SQL statement.

$start = 0; $end = 0;

$orig = array(
    array('id' => 1,  'title' => 'title 1'),
    array('id' => 10, 'title' => 'title 10'),
    array('id' => 11, 'title' => 'title 11')
);

// A
$start = microtime(true);
for ($a=0; $a<1000; $a++) {
    $els1 = $orig;
    array_walk($els1, function(&$val, $key){$val['type'] = 'bag';});
}
$end = microtime(true);
echo 'A: ', $end - $start,  "<br />\n";

// B
$start = microtime(true);
for ($b=0; $b<1000; $b++) {
    $els2 = $orig;
    foreach ($els2 as &$el) {
        $el['type'] = 'bag';
    }
    unset($el);
}
$end = microtime(true);
echo 'B: ', $end - $start,  "<br />\n";

/* output:

A: 0.0076138973236084
B: 0.0047528743743896

A: 0.0075309276580811
B: 0.0045361518859863

A: 0.0075531005859375
B: 0.062379837036133

A: 0.0075340270996094
B: 0.0044951438903809

A: 0.0074868202209473
B: 0.0044751167297363

A: 0.0076088905334473
B: 0.0048189163208008

*/

Answer 2

From a simple/clean code point of view this solution suits:

$orig = array(
array('id' => 1,  'title' => 'title 1'),
array('id' => 10, 'title' => 'title 10'),
array('id' => 11, 'title' => 'title 11'));

foreach($orig as $key => $value)
{
    $value['type'] = 'bag';
    $orig[$key] = $value;   
}

Answer 3

Logically, no, there isn't any way to do it without iterating the parent array. But you can make it less painful by using array_walk() . EDIT: benchmark shows array_walk (or array-_map) is slower by a third, so I take this back.