Online PHP editor | output for Qag3c

<?php $items = array( array("itemName" => "Hat", "price" => 10.99, "categories" => ["apparel", "head"]), array("itemName" => "Scarf", "price" => 7.99, "categories" => ["apparel", "neck"]), array("itemName" => "Watch", "price" => 19.99, "categories" => ["jewelry", "electronics"]), array("itemName" => "Necklace", "price" => 99.99, "categories" => ["jewelry", "neck"]), array("itemName" => "Headphones", "price" => 29.99, "categories" => ["head", "electronics"]) ); foreach (array_unique(array_merge(...array_values(array_column($items, 'categories')))) as $value) { foreach ($items as $item) { if (in_array($value, $item['categories'])) { $categories[$value][] = $item['itemName']; } } } print_r($categories);