In PHP, is there a function that returns an array made up of the value of a key from an array of associative arrays?

Question

I\'m sure this question has been asked before, my apologies for not finding it first.

The original array:

[0] => Array
    (
        [categoryId]          


        

Answer 1

 1, 'b' => 2),
        array('a' => 2, 'b' => 2),
        array('a' => 3, 'b' => 2),
        array('a' => 4, 'b' => 2)
);

function get_a($v) {
        return $v['a'];
}

var_dump(array_map('get_a', $a));

You can use an create_function or an anonymous function (PHP 5.3 >=)

 1, 'b' => 2),
        array('a' => 2, 'b' => 2),
        array('a' => 3, 'b' => 2),
        array('a' => 4, 'b' => 2)
);

var_dump(array_map(create_function('$v', 'return $v["a"];'), $a));

I'd write a callback function, as above, and then use it with array_map.