- array_column: documentation ( source)
- print_r: documentation ( source)
<?php
$episodes = [
1 => [
['el' => 1, 's' => 1, 'ep' => 101],
['el' => 1, 's' => 1, 'ep' => 102],
['el' => 1, 's' => 2, 'ep' => 103],
['el' => 1, 's' => 3, 'ep' => 104],
]
];
print_r(array_column((array) $episodes[1], 'ep', 's'));