PHP- Loop through multidimensional array and reduce arrays if key found

Question

I have an array that looks like this:

array:3 [
  0 => array:5 [
    "id" => 18
    "product_id" => 37
    "total_price" => "643.00"
    "created_at" => "2017-05-02 13:22:35"
    "updated_at" => "2017-05-02 13:22:35"
  ]
  1 => array:5 [
    "id" => 19
    "product_id" => 36
    "total_price" => "532.00"
    "created_at" => "2017-05-02 13:23:47"
    "updated_at" => "2017-05-02 13:23:47"
  ]
  2 => array:5 [
    "id" => 20
    "product_id" => 36
    "total_price" => "532.00"
    "created_at" => "2017-05-03 13:20:47"
    "updated_at" => "2017-05-03 13:20:47"
  ]
]

In my case if the key "product_id" has the same value I want to reduce merge those arrays and add the total_price but I have to also save a new key to the new array: $quantity to store the number of array with the same key that existed before merging. So the final result should look like this:

array:2 [
  0 => array:5 [
    "id" => 18
    "product_id" => 37
    "total_price" => "643.00"
    "quantity"   => 1
    "created_at" => "2017-05-02 13:22:35"
    "updated_at" => "2017-05-02 13:22:35"
  ]
  1 => array:5 [
    "id" => 19
    "product_id" => 36
    "total_price" => "1064.00"
    "quantity"   => 2
    "created_at" => "2017-05-02 13:23:47"
    "updated_at" => "2017-05-02 13:23:47"
  ]
]

Initially I tried with array_walk_recursive, but I got confused.

array_walk_recursive($products, function($value, $key) use (&$products_sold){
            array_push($products_sold, isset($products_sold[$key]) ?  $value + $products_sold[$key] : $value);
        });

I know this is useless but I failed to realize how to do this. Any explanation would be helpful. Thank you all for your time!

Nikita U. · Accepted Answer · 2017-05-24 05:49:49Z

2

Try

$result = array_reduce($products, function ($result, $product) {
    foreach ($result as $index => $value) {
        if ($value['product_id'] == $product['product_id']) {
            $result[$index]['total_price'] += $product['total_price'];

            return $result;
        }
    }
    $result[] = $product;
    return $result;
}, []);

But I strongly recomment use BCMath functions instead of working with floats.

So its better to write

$result[$index]['total_price'] = bcadd($result[$index]['total_price'], $product['total_price'], 2);

instead of

$result[$index]['total_price'] += $product['total_price'];

Update

We can rewrite above version to nested foreach like so:

$reducer = function ($result, $product) {
    foreach ($result as $index => $value) {
        if ($value['product_id'] == $product['product_id']) {
            $result[$index]['total_price'] += $product['total_price'];

            return $result;
        }
    }
    $result[] = $product;
    return $result;
};

$result = [];

foreach($products as $product) {
    $result = $reducer($result, $product);
}

so we can see it is just foreach loop which calls function which contains another foreach. We need another foreach because we need the way to determine if array contains product_id. We can index result with product_id so we can avoid secind foreach:

$result = array_reduce($products, function ($result, $product) {
    $productId = $product['product_id'];
    if(isset($result[$productId])) {
        $result[$productId]['total_price'] += $product['total_price'];
        return $result;
    }
    $result[$productId] = $product;
    return $result;
}, []);

and then if you need indexes to be ordered from zero just call array_values($result)

edited May 24, 2017 at 5:49

answered May 23, 2017 at 11:21

Nikita U.

3,6381 gold badge31 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Alphonse Over a year ago

sadly I get: Invalid argument supplied for foreach() @Nikita

Nikita U. Over a year ago

little fix added :)

Alphonse Over a year ago

It works perffectly now, thank you! But can you explain to me a bit the part with result please? I mean you make result equal with the array_reduce(which return the products reduced?) and inside of it you loop through $result...that's the part that I don't get.

WasteD · Accepted Answer · 2017-05-23 12:19:56Z

2

Got it done! I should say I didnt use total_price as string so I can do addition.

$stuff = array(
    array(
        "id" => 18,
        "product_id" => 37,
        "total_price" => 643.00,
        "created_at" => "2017-05-02 13:22:35",
        "updated_at" => "2017-05-02 13:22:35"),

    array(
        "id" => 19,
        "product_id" => 36,
        "total_price" => 532.00,
        "created_at" => "2017-05-02 13:23:47",
        "updated_at" => "2017-05-02 13:23:47"),

    array(
        "id" => 20,
        "product_id" => 36,
        "total_price" => 532.00,
        "created_at" => "2017-05-03 13:20:47",
        "updated_at" => "2017-05-03 13:20:47")
    );

for ($i=0; $i < count($stuff); $i++) { 
    $product_id = $stuff[$i]["product_id"];
    foreach ($stuff as $key => $value) {
        if($value["product_id"] === $product_id && $i !== $key) {
            $stuff[$i]["total_price"] += $value["total_price"];
            unset($stuff[$key]);
        }
    }
}

edited May 23, 2017 at 12:19

answered May 23, 2017 at 11:36

WasteD

7786 silver badges25 bronze badges

4 Comments

Alphonse Over a year ago

Undefined offset: 2..that is for the $product_id apparently while looping it gets out of bounds

WasteD Over a year ago

Huh this works for me and I cant see why you should get out of bounds...

Nikita U. Over a year ago

I don't think intval is safe to use here, because you'll lose cents

WasteD Over a year ago

@NikitaU. Yeah I dont even use it anymore because in his example total_price is a string thats why I used intval but now that I use number for total_price, I can remove intval.

Collectives™ on Stack Overflow

PHP- Loop through multidimensional array and reduce arrays if key found

2 Answers 2

3 Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related