Online PHP editor | refs for YflAQ

<?php $array = [ [ 2 => 'kategorie_01', 'tags' => [ 1 => 'tag_01', 2 => 'tag_02', ], ], [ 3 => 'kategorie_02', 'tags' => [ 2 => 'tag_02', ], ], [ 1 => 'Default', 'tags' => [ 1 => 'tag_01', 2 => 'tag_02', ], ], [ 2 => 'kategorie_01', 'tags' => [ 2 => 'tag_02', 3 => 'tag_03', ], ], ]; $result = []; foreach ($array as $set) { foreach ($set as $k => $v) { if ($k !== 'tags') { $cat = $v; if (!isset($ref[$v])) { $ref[$v] = $set; $result[] = &$ref[$v]; } } else { $ref[$cat]['tags'] += $v; } } } var_export($result);