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

There's no built-in function for this, but it's usually referred as "pluck".

Answer 2

Mapping is what you need:

$input = array(
    array(
        'categoryId' => 1,
        'eventId' => 2,
        'eventName' => 3,
        'vendorName' => 4,
    ),
    array(
        'categoryId' => 5,
        'eventId' => 6,
        'eventName' => 7,
        'vendorName' => 8,
    ),
    array(
        'categoryId' => 9,
        'eventId' => 10,
        'eventName' => 11,
        'vendorName' => 12,
    ),
);

$result = array_map(function($val){
    return $val['categoryId'];
}, $input);

Or creating a function you wanted:

function get_values_from_a_key_in_arrays($key, $input){
    return array_map(function($val) use ($key) {
        return $val[$key];
    }, $input);
};

and then using it:

$result = get_values_from_a_key_in_arrays('categoryId', $array);

It will work in PHP >= 5.3, where anonymous callbacks are allowed. For earlier versions you will need to define callback earlier and pass its name instead of anonymous function.