Return single column from a multi-dimensional array [duplicate]

Quite simple:

$input = array(
  array(
    'tag_name' => 'google'
  ),
  array(
    'tag_name' => 'technology'
  )
);

echo implode(', ', array_map(function ($entry) {
  return $entry['tag_name'];
}, $input));

http://3v4l.org/ltBZ0

and new in php v5.5.0, array_column:

echo implode(', ', array_column($input, 'tag_name'));