array column in php

1$a = array(
2  array(
3    'id' => 5698,
4    'first_name' => 'Peter',
5    'last_name' => 'Griffin',
6  ),
7  array(
8    'id' => 4767,
9    'first_name' => 'Ben',
10    'last_name' => 'Smith',
11  ),
12  array(
13    'id' => 3809,
14    'first_name' => 'Joe',
15    'last_name' => 'Doe',
16  )
17);
18
19$last_names = array_column($a, 'last_name');
20print_r($last_names);