PHP traverse category subcategory tree array into a custom 2D array

Question

I have an parent child array similar to this:

How to convert this array similar to this:

Array
(
    [0] => Array
        (
            [0] => Home & Garden
            [1] => Kitchen & Dining
            [2] => Food & Beverage Carriers
            [3] => Flasks
            [4] => 
        )

    [1] => Array
        (
            [0] => 
            [1] => 
            [2] => 
            [3] => Canteens
            [4] => 
        )

    [2] => Array
        (
            [0] => 
            [1] => 
            [2] => Barware
            [3] => Drink Shakers & Tools
            [4] => Bottle Openers
        )

    [3] => Array
        (
            [0] => 
            [1] => 
            [2] => Tableware
            [3] => Drinkware
            [4] => Mugs
        )

    [4] => Array
        (
            [0] => 
            [1] => Parasols & Umbrellas
            [2] => 
            [3] => 
            [4] => 
        )

    [5] => Array
        (
            [0] => 
            [1] => Parasols & Rain Umbrellas
            [2] => 
            [3] => 
            [4] => 
        )

    [6] => Array
        (
            [0] => Clothing & Accessories
            [1] => Clothing
            [2] => Shorts
            [3] => Cargo Shorts 
            [4] => 
        )

)

Parent child representation for reference:

enter image description here

Any Ideas???

Can you explain what is parent id? It is category id? If fo, can you show your category ids? — stepozer, Feb 05 '15 at 12:03
Hi, Yes parent_id is category_id.I've updated the array with category_id,Please check & let me know — PHPDev, Feb 05 '15 at 12:10

stepozer · Accepted Answer · 2015-02-05T16:42:04.430

Very interesting task. See my solution below:

categories array

$categoriesrRaw = Array
(
    '0' => Array
        (
            'category_id' => 1,
            'category_name' => 'Home & Garden',
            'parent_id' => 0,
            'level' => 1,
        ),

    '1' => Array
        (
            'category_id' => 2,
            'category_name' => 'Kitchen & Dining',
            'parent_id' => 1,
            'level' => 2,
        ),

    '2' => Array
        (
            'category_id' => 3,
            'category_name' => 'Food & Beverage Carriers',
            'parent_id' => 2,
            'level' => 3,
        ),

    '3' => Array
        (
            'category_id' => 4,
            'category_name' => 'Flasks',
            'parent_id' => 3,
            'level' => 4,
        ),

    '4' => Array
        (
            'category_id' => 5,
            'category_name' => 'Clothing & Accessories',
            'parent_id' => 0,
            'level' => 1,
        ),

    '5' => Array
        (
            'category_id' => 6,
            'category_name' => 'Clothing',
            'parent_id' => 5,
            'level' => 2,
        ),

    '6' => Array
        (
            'category_id' => 7,
            'category_name' => 'Shorts',
            'parent_id' => 6,
            'level' => 3,
        ),

    '7' => Array
        (
            'category_id' => 8,
            'category_name' => 'Shirts & Tops',
            'parent_id' => 6,
            'level' => 3,
        ),

    '8' => Array
        (
            'category_id' => 9,
            'category_name' => 'Jumpers & Cardigans',
            'parent_id' => 8,
            'level' => 4,
        ),

    '9' => Array
        (
            'category_id' => 10,
            'category_name' => 'T-Shirts',
            'parent_id' => 8,
            'level' => 4,
        ),

    '10' => Array
        (
            'category_id' => 11,
            'category_name' => 'Skirts',
            'parent_id' => 6,
            'level' => 3,
        ),

    '11' => Array
        (
            'category_id' => 12,
            'category_name' => 'Shirts & Blouses',
            'parent_id' => 8,
            'level' => 4,
        ),

    '12' => Array
        (
            'category_id' => 13,
            'category_name' => 'Trousers & Jeans',
            'parent_id' => 6,
            'level' => 3,
        ),

    '13' => Array
        (
            'category_id' => 14,
            'category_name' => 'Chinos',
            'parent_id' => 13,
            'level' => 4,
        ),

    '14' => Array
        (
            'category_id' => 15,
            'category_name' => 'Tops',
            'parent_id' => 6,
            'level' => 3,
        ),

    '15' => Array
        (
            'category_id' => 16,
            'category_name' => 'Sweatshirts',
            'parent_id' => 8,
            'level' => 4,
        ),

    '16' => Array
        (
            'category_id' => 17,
            'category_name' => 'Clothing Accessories',
            'parent_id' => 5,
            'level' => 2,
        ),

    '17' => Array
        (
            'category_id' => 18,
            'category_name' => 'Hats',
            'parent_id' => 17,
            'level' => 3,
        ),

    '18' => Array
        (
            'category_id' => 19,
            'category_name' => 'Shirts',
            'parent_id' => 15,
            'level' => 4,
        ),

    '19' => Array
        (
            'category_id' => 20,
            'category_name' => 'Cargo Trousers',
            'parent_id' => 13,
            'level' => 4,
        ),

    '20' => Array
        (
            'category_id' => 21,
            'category_name' => 'Underwear & Socks',
            'parent_id' => 6,
            'level' => 3,
        ),

    '21' => Array
        (
            'category_id' => 22,
            'category_name' => 'Socks',
            'parent_id' => 21,
            'level' => 4,
        ),

    '22' => Array
        (
            'category_id' => 23,
            'category_name' => 'Polo Shirts',
            'parent_id' => 8,
            'level' => 4,
        ),

    '23' => Array
        (
            'category_id' => 24,
            'category_name' => 'Apparel & Accessories',
            'parent_id' => 0,
            'level' => 1,
        ),

    '24' => Array
        (
            'category_id' => 25,
            'category_name' => 'Clothing Accessories',
            'parent_id' => 24,
            'level' => 2,
        ),

    '25' => Array
        (
            'category_id' => 26,
            'category_name' => 'Belts',
            'parent_id' => 25,
            'level' => 3,
        ),

    '26' => Array
        (
            'category_id' => 27,
            'category_name' => 'Gloves & Mittens',
            'parent_id' => 17,
            'level' => 3,
        ),

    '27' => Array
        (
            'category_id' => 28,
            'category_name' => 'Gloves',
            'parent_id' => 27,
            'level' => 4,
        ),

    '28' => Array
        (
            'category_id' => 29,
            'category_name' => 'Shoes',
            'parent_id' => 24,
            'level' => 2,
        ),

    '29' => Array
        (
            'category_id' => 30,
            'category_name' => 'Sandals',
            'parent_id' => 29,
            'level' => 3,
        ),

    '30' => Array
        (
            'category_id' => 31,
            'category_name' => 'Thongs & Flip-Flops',
            'parent_id' => 30,
            'level' => 4,
        ),

    '31' => Array
        (
            'category_id' => 32,
            'category_name' => 'Luggage & Bags',
            'parent_id' => 0,
            'level' => 1,
        ),

    '32' => Array
        (
            'category_id' => 33,
            'category_name' => 'Messenger Bags',
            'parent_id' => 32,
            'level' => 2,
        ),

    '33' => Array
        (
            'category_id' => 34,
            'category_name' => 'Jeans',
            'parent_id' => 13,
            'level' => 4,
        ),

    '34' => Array
        (
            'category_id' => 35,
            'category_name' => 'Clothing',
            'parent_id' => 24,
            'level' => 2,
        ),

    '35' => Array
        (
            'category_id' => 36,
            'category_name' => 'Pants',
            'parent_id' => 35,
            'level' => 3,
        ),

    '36' => Array
        (
            'category_id' => 37,
            'category_name' => 'Jeans',
            'parent_id' => 36,
            'level' => 4,
        ),

    '37' => Array
        (
            'category_id' => 38,
            'category_name' => 'Handbags, Wallets & Cases',
            'parent_id' => 5,
            'level' => 2,
        ),

    '38' => Array
        (
            'category_id' => 39,
            'category_name' => 'Wallets & Money Clips',
            'parent_id' => 38,
            'level' => 3,
        ),

    '39' => Array
        (
            'category_id' => 40,
            'category_name' => 'Baseball Hats',
            'parent_id' => 18,
            'level' => 4,
        ),

    '40' => Array
        (
            'category_id' => 41,
            'category_name' => 'Handbag & Wallet Accessories',
            'parent_id' => 5,
            'level' => 2,
        ),

    '41' => Array
        (
            'category_id' => 42,
            'category_name' => 'Key Chains',
            'parent_id' => 41,
            'level' => 3,
        ),

    '42' => Array
        (
            'category_id' => 43,
            'category_name' => 'Shoes',
            'parent_id' => 5,
            'level' => 2,
        ),

    '43' => Array
        (
            'category_id' => 44,
            'category_name' => 'Boots',
            'parent_id' => 43,
            'level' => 3,
        ),

    '44' => Array
        (
            'category_id' => 45,
            'category_name' => 'Waterproof Boots & Wellingtons',
            'parent_id' => 44,
            'level' => 4,
        ),

    '45' => Array
        (
            'category_id' => 46,
            'category_name' => 'Barware',
            'parent_id' => 2,
            'level' => 3,
        ),

    '46' => Array
        (
            'category_id' => 47,
            'category_name' => 'Drink Shakers & Tools',
            'parent_id' => 46,
            'level' => 4,
        ),

    '47' => Array
        (
            'category_id' => 48,
            'category_name' => 'Bottle Openers',
            'parent_id' => 47,
            'level' => 5,
        ),

    '48' => Array
        (
            'category_id' => 49,
            'category_name' => 'Tableware',
            'parent_id' => 2,
            'level' => 3,
        ),

    '49' => Array
        (
            'category_id' => 50,
            'category_name' => 'Drinkware',
            'parent_id' => 49,
            'level' => 4,
        ),

    '50' => Array
        (
            'category_id' => 51,
            'category_name' => 'Mugs',
            'parent_id' => 50,
            'level' => 5,
        ),

    '51' => Array
        (
            'category_id' => 52,
            'category_name' => 'Outerwear',
            'parent_id' => 6,
            'level' => 3,
        ),

    '52' => Array
        (
            'category_id' => 53,
            'category_name' => 'Coats & Jackets',
            'parent_id' => 52,
            'level' => 4,
        ),

    '53' => Array
        (
            'category_id' => 54,
            'category_name' => 'Puffer jackets',
            'parent_id' => 53,
            'level' => 5,
        ),

    '54' => Array
        (
            'category_id' => 55,
            'category_name' => 'Shirts & Tops',
            'parent_id' => 35,
            'level' => 3,
        ),

    '55' => Array
        (
            'category_id' => 56,
            'category_name' => 'T-Shirts',
            'parent_id' => 55,
            'level' => 4,
        ),

    '56' => Array
        (
            'category_id' => 57,
            'category_name' => 'T-Shirts',
            'parent_id' => 15,
            'level' => 4,
        ),

    '57' => Array
        (
            'category_id' => 58,
            'category_name' => 'Sandals',
            'parent_id' => 43,
            'level' => 3,
        ),

    '58' => Array
        (
            'category_id' => 59,
            'category_name' => 'Thongs & Flip Flops',
            'parent_id' => 58,
            'level' => 4,
        ),

    '59' => Array
        (
            'category_id' => 60,
            'category_name' => 'Belts',
            'parent_id' => 17,
            'level' => 3,
        ),

    '60' => Array
        (
            'category_id' => 61,
            'category_name' => 'Cargo Shorts',
            'parent_id' => 7,
            'level' => 4,
        ),

    '61' => Array
        (
            'category_id' => 62,
            'category_name' => 'Jumpers & Cardigans',
            'parent_id' => 15,
            'level' => 4,
        ),

    '62' => Array
        (
            'category_id' => 63,
            'category_name' => 'Cosmetic & Toiletry Bags',
            'parent_id' => 32,
            'level' => 2,
        ),

    '63' => Array
        (
            'category_id' => 64,
            'category_name' => 'Activewear',
            'parent_id' => 35,
            'level' => 3,
        ),

    '64' => Array
        (
            'category_id' => 65,
            'category_name' => 'Sweatshirts',
            'parent_id' => 64,
            'level' => 4,
        ),

    '65' => Array
        (
            'category_id' => 66,
            'category_name' => 'Sun Hats',
            'parent_id' => 18,
            'level' => 4,
        ),

    '66' => Array
        (
            'category_id' => 67,
            'category_name' => 'Fleece Jackets',
            'parent_id' => 53,
            'level' => 5,
        ),

    '67' => Array
        (
            'category_id' => 68,
            'category_name' => 'Gilets',
            'parent_id' => 52,
            'level' => 4,
        ),

    '68' => Array
        (
            'category_id' => 69,
            'category_name' => 'Handbags',
            'parent_id' => 38,
            'level' => 3,
        ),

    '69' => Array
        (
            'category_id' => 70,
            'category_name' => 'Tote Bags & Shoppers',
            'parent_id' => 69,
            'level' => 4,
        ),

    '70' => Array
        (
            'category_id' => 71,
            'category_name' => 'Outdoor Shoes',
            'parent_id' => 29,
            'level' => 3,
        ),

    '71' => Array
        (
            'category_id' => 72,
            'category_name' => 'Water Shoes',
            'parent_id' => 71,
            'level' => 4,
        ),

    '72' => Array
        (
            'category_id' => 73,
            'category_name' => 'Backpacks',
            'parent_id' => 32,
            'level' => 2,
        ),

    '73' => Array
        (
            'category_id' => 74,
            'category_name' => 'Shirts & Blouses',
            'parent_id' => 55,
            'level' => 4,
        ),

    '74' => Array
        (
            'category_id' => 75,
            'category_name' => 'Scarves & Snoods',
            'parent_id' => 17,
            'level' => 3,
        ),

    '75' => Array
        (
            'category_id' => 76,
            'category_name' => 'Suitcases',
            'parent_id' => 32,
            'level' => 2,
        ),

    '76' => Array
        (
            'category_id' => 77,
            'category_name' => 'Hand Luggage',
            'parent_id' => 76,
            'level' => 3,
        ),

    '77' => Array
        (
            'category_id' => 78,
            'category_name' => 'Vests & Tank Tops',
            'parent_id' => 8,
            'level' => 4,
        ),

    '78' => Array
        (
            'category_id' => 79,
            'category_name' => 'Parasols & Umbrellas',
            'parent_id' => 1,
            'level' => 2,
        ),

    '79' => Array
        (
            'category_id' => 80,
            'category_name' => 'Carry-On Luggage',
            'parent_id' => 76,
            'level' => 3,
        ),

    '80' => Array
        (
            'category_id' => 81,
            'category_name' => 'Dresses',
            'parent_id' => 6,
            'level' => 3,
        ),

    '81' => Array
        (
            'category_id' => 82,
            'category_name' => 'Day Dresses',
            'parent_id' => 81,
            'level' => 4,
        ),

    '82' => Array
        (
            'category_id' => 83,
            'category_name' => 'Cargo Pants',
            'parent_id' => 13,
            'level' => 4,
        ),

    '83' => Array
        (
            'category_id' => 84,
            'category_name' => 'Hand Luggage',
            'parent_id' => 32,
            'level' => 2,
        ),

    '84' => Array
        (
            'category_id' => 85,
            'category_name' => 'Shoulder Bags',
            'parent_id' => 69,
            'level' => 4,
        ),

    '85' => Array
        (
            'category_id' => 86,
            'category_name' => 'Bermuda Shorts',
            'parent_id' => 7,
            'level' => 4,
        ),

    '86' => Array
        (
            'category_id' => 87,
            'category_name' => 'Shorts',
            'parent_id' => 35,
            'level' => 3,
        ),

    '87' => Array
        (
            'category_id' => 88,
            'category_name' => 'Cargo Shorts',
            'parent_id' => 87,
            'level' => 4,
        ),

    '88' => Array
        (
            'category_id' => 89,
            'category_name' => 'Trousers',
            'parent_id' => 6,
            'level' => 3,
        ),

    '89' => Array
        (
            'category_id' => 90,
            'category_name' => 'Casual Trousers',
            'parent_id' => 89,
            'level' => 4,
        ),

    '90' => Array
        (
            'category_id' => 91,
            'category_name' => 'Handbag & Wallet Accessories',
            'parent_id' => 24,
            'level' => 2,
        ),

    '91' => Array
        (
            'category_id' => 92,
            'category_name' => 'Lanyards',
            'parent_id' => 91,
            'level' => 3,
        ),

    '92' => Array
        (
            'category_id' => 93,
            'category_name' => 'Duffel Bags',
            'parent_id' => 32,
            'level' => 2,
        ),

    '93' => Array
        (
            'category_id' => 94,
            'category_name' => 'Polo Shirts',
            'parent_id' => 15,
            'level' => 4,
        ),

    '94' => Array
        (
            'category_id' => 95,
            'category_name' => 'Skorts',
            'parent_id' => 6,
            'level' => 3,
        ),

    '95' => Array
        (
            'category_id' => 96,
            'category_name' => 'Casual Jackets',
            'parent_id' => 53,
            'level' => 5,
        ),

    '96' => Array
        (
            'category_id' => 97,
            'category_name' => 'Leggings',
            'parent_id' => 89,
            'level' => 4,
        ),

    '97' => Array
        (
            'category_id' => 98,
            'category_name' => 'Canteens',
            'parent_id' => 3,
            'level' => 4,
        ),

    '98' => Array
        (
            'category_id' => 99,
            'category_name' => 'Caps',
            'parent_id' => 18,
            'level' => 4,
        ),

    '99' => Array
        (
            'category_id' => 100,
            'category_name' => 'Baseball Hats',
            'parent_id' => 99,
            'level' => 5,
        ),

    '100' => Array
        (
            'category_id' => 101,
            'category_name' => 'Rain Gear',
            'parent_id' => 52,
            'level' => 4,
        ),

    '101' => Array
        (
            'category_id' => 102,
            'category_name' => 'Waterproof Coats',
            'parent_id' => 101,
            'level' => 5,
        ),

    '102' => Array
        (
            'category_id' => 103,
            'category_name' => 'Capes & Ponchos',
            'parent_id' => 53,
            'level' => 5,
        ),

    '103' => Array
        (
            'category_id' => 104,
            'category_name' => 'Sweatshirts',
            'parent_id' => 15,
            'level' => 4,
        ),

    '104' => Array
        (
            'category_id' => 105,
            'category_name' => 'Outdoor Shoes',
            'parent_id' => 43,
            'level' => 3,
        ),

    '105' => Array
        (
            'category_id' => 106,
            'category_name' => 'Water Shoes',
            'parent_id' => 105,
            'level' => 4,
        ),

    '106' => Array
        (
            'category_id' => 107,
            'category_name' => 'Polo Shirts',
            'parent_id' => 55,
            'level' => 4,
        ),

    '107' => Array
        (
            'category_id' => 108,
            'category_name' => 'Dresses',
            'parent_id' => 35,
            'level' => 3,
        ),

    '108' => Array
        (
            'category_id' => 109,
            'category_name' => 'Day Dresses',
            'parent_id' => 108,
            'level' => 4,
        ),

    '109' => Array
        (
            'category_id' => 110,
            'category_name' => 'Sweaters & Cardigans',
            'parent_id' => 55,
            'level' => 4,
        ),

    '110' => Array
        (
            'category_id' => 111,
            'category_name' => 'Shopping Totes',
            'parent_id' => 32,
            'level' => 2,
        ),

    '111' => Array
        (
            'category_id' => 112,
            'category_name' => 'Sweatshirts',
            'parent_id' => 55,
            'level' => 4,
        ),

    '112' => Array
        (
            'category_id' => 113,
            'category_name' => 'Scarves & Shawls',
            'parent_id' => 25,
            'level' => 3,
        ),

    '113' => Array
        (
            'category_id' => 114,
            'category_name' => 'Handbags, Wallets & Cases',
            'parent_id' => 24,
            'level' => 2,
        ),

    '114' => Array
        (
            'category_id' => 115,
            'category_name' => 'Handbags',
            'parent_id' => 114,
            'level' => 3,
        ),

    '115' => Array
        (
            'category_id' => 116,
            'category_name' => 'Tote Handbags',
            'parent_id' => 115,
            'level' => 4,
        ),

    '116' => Array
        (
            'category_id' => 117,
            'category_name' => 'Underwear & Socks',
            'parent_id' => 35,
            'level' => 3,
        ),

    '117' => Array
        (
            'category_id' => 118,
            'category_name' => 'Socks',
            'parent_id' => 117,
            'level' => 4,
        ),

    '118' => Array
        (
            'category_id' => 119,
            'category_name' => 'Cross-Body Handbags',
            'parent_id' => 115,
            'level' => 4,
        ),

    '119' => Array
        (
            'category_id' => 120,
            'category_name' => 'Underwear',
            'parent_id' => 117,
            'level' => 4,
        ),

);

code

function categoriesCmd($a, $b)
{
        return strnatcmp($a['path'], $b['path']);
}

// 
// sort all categories values by path. Path - it is category parent ids:
// 1
// 1/2
// 1/2/3
// 1/2/3/4
// 1/2/3/98
// 1/2/46
// 1/2/46/47
// 1/2/46/47/48
// 1/2/49
// etc
//
$maxLevel   = 0;
$categories = array();
foreach ($categoriesrRaw as $key => $category) {
    $parentId = $category['parent_id'];
    $category['path']  = array($category['category_id']);
    if ($maxLevel < $category['level']) {
        $maxLevel = $category['level'];
    }
    while ($parentId) {
        foreach ($categoriesrRaw as $item) {
            if ($item['category_id'] == $parentId) {
                $newParentId = $item['parent_id'];
                $category['path'][] = $item['category_id'];
                break;
            }
        }
        $parentId = $newParentId;
        // $category['level']++;
    }
    $category['path'] = implode('/', array_reverse($category['path']));
    $categories[]    = $category;
}
usort($categories, 'categoriesCmd');



//
// create needed array structure
//
$prev         = array_shift($categories);
$level        = 0;
$result       = array(array_fill(0, $maxLevel, ""));
$result[0][0] = $category['category_name'];
foreach ($categories as $category) {
    if ($prev['level'] >= $category['level']) {
        $level++;
        $result[$level] = array_fill(0, $maxLevel, "");
    }

    $result[$level][$category['level']-1] = $category['category_name'];
    $prev = $category;
}

print_r($result);

PHP traverse category subcategory tree array into a custom 2D array

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