Compare array values with others values from the same array

I hope this can help you:

        $sortedArray = [];
        foreach ($order as $array) {
            $tag = getTag($array);
            push_to_array($sortedArray,$array,$tag);
        }



        function push_to_array(&$array1,$array2,$tag)
        {
            isset($array1[$tag]) ? $array1[$tag]['quantity'] += $array2['quantity'] : $array1[$tag] = $array2;
        }
        function getTag($array)
        {
            $attribs = json_decode($array['attributes'],true);
            foreach ($attribs as $value) {
                ($value['name'] =='Size' ) && $size = $value['value'];
                ($value['name'] =='Color') && $color= $value['value'];
            }
            return $array['product_id'].$size.$color;
        }

Try this (untested but logic should be correct):

$orders = // original array;
$new;     // new array

foreach($orders as $order) {
    $pi = $order["product_id"];                // get product_id
    $attr = json_decode($order["attributes"]); // get attributes:
    $size = $attr[0]->value;                   // get size value
    $color = $attr[1]->Color;                  // get color
    $duplicate = false;
    foreach($newOrders as $newOrder() {        // loop through nested array
        $newPi = $newOrder["product_id"];
        $newAttr = json_decode($newOrder["attributes"]);
        $newSize = $newAttr[0]->value;
        $newValue = $newAttr[1]->Color;

        // check to see if same
        if(
            $pi == $newPi &&
            $size == $newSize &&
            $color == $newColor
        ) {
            $newOrders["quantity"]++;
            $duplicate = true;
            break;
        }
    }
    if(!$duplicate) {
        $new[] = $order;
    }
}

Edit: Sorry, I just reread your post and saw you don't want a full solution. Sorry. But I hope this can show you that nested loops are the way to go with this. As mentioned in the comments, there is no built in function for this in PHP (AFAIK).

This is not a solution, but another approach to let you think by Object Oriented Programming
It will helps you a lot in you current and next problems

Now, you have a business case, that it must be resolved in your business layer
I can assist you if you want

<?php

class Attribute {
    private $_id;
    private $_name;
    private $_value;
    private $_active;

    // TODO implement getter and setter 
    // lTODO implement constructor
}

class Product {
    private $_id;
    private $_productId;
    // ... order_id, name, ...
    private $_attribute_a = array(); // it will be an array of attribute's object

    // TODO implement getter and setter 
    // TODO implement constructor

    private function getAttributeByName($name) {
        // loop through attribute array object and return the right attribute
        // foreach ($this->_attribute_a as $attr) {
        //      if ($attr->name === $name) return $attr;
        // }
    }

    public function equals($o) {
        if (!is_a($o, 'Product'))   return FALSE;
        if ($this == $o)            return TRUE ;

        if ($this->_productId === $o->_productId) {
            $attr1 = $this->getAttributeByName('Size');
            $attr2 = $this->getAttributeByName('Size');
            if ($attr1->getValue() !== $attr2->getValue()) return FALSE; 

            $attr1 = $this->getAttributeByName('Color');
            $attr2 = $this->getAttributeByName('Color');
            if ($attr1->getValue() !== $attr2->getValue()) return FALSE; 
            return TRUE;
        }
        return FALSE;
    }
}

Now, you can compare easily 2 Products Object, and later, updating equals() will not affect your code

You have some grate answers from other users.

However i would like to post this for Googlers or other users in the planning stage and for your own knowledge.

With your example your using a shopping basket. You should never have duplicate items in the array you should be using a Quantity measure on the item and before adding to your array you check the array if the matching item is there increase the quantity.

as your current way your code is processing though the array after for no good reason if i was to add 20 of the same item your current system would have an array of 20 to loop though every time i opened the basket.

This other method will also provide you will support for people to add multiple quantities of items at once, also on your basket page edit the quantities

Please note the assumptions below the code

function combineDuplicates($orders) {
$indexArray = array();
$uniqueArray = array();
foreach($orders as $value) {
    $productID = $value['product_id'];
    $attributes = $value['attributes'];
    foreach($attributes as $attribute) {
        switch($attribute['name']) {
            case 'Size' :   $size = $attribute['value'];
                            break;
            case 'Color':   $color = $attribute['value'];
                            break;
            default : break;
        }
    }
    if (!isset($indexArray[$productID][$size][$color])) {
        $indexArray[$productID][$size][$color]['count'] = 0;
        $uniqueArray[] = $value;
    }
    $indexArray[$productID][$size][$color]['count']++;
}
$orders = array();
foreach($uniqueArray as $key => $value) {
    $productID = $value['product_id'];
    $attributes = $value['attributes'];
    foreach($attributes as $attribute) {
        switch($attribute['name']) {
            case 'Size' :   $size = $attribute['value'];
                            break;
            case 'Color':   $color = $attribute['value'];
                            break;
            default : break;
        }
    }
    $uniqueArray[$key]['quantity'] = $indexArray[$productID][$size][$color]['count'];
}
return $uniqueArray;
}

Assumptions :

• 'attributes' is converted to associative array
• product_id, Color & Size values are non-empty in each element