Sorting a Multi-Dimensional Array by sum of object values in PHP

Question

I have the below multi dimensional array of products. Each array is a pair of products that make a product set, I need to order the multi dimensional array by the total price of each product set.

array(4) {
  [0]=>
  array(2) {
    ["product1"]=>
    object(stdClass)#5075 (2) {
      ["product_id"]=>
      string(4) "9416"
      ["price"]=>
      string(6) "110.00"
    }
    ["product2"]=>
    object(stdClass)#5077 (2) {
      ["product_id"]=>
      string(4) "9431"
      ["price"]=>
      string(6) "100.00"
    }
  }
  [1]=>
  array(2) {
    ["product1"]=>
    object(stdClass)#5065 (2) {
      ["product_id"]=>
      string(4) "1254"
      ["price"]=>
      string(6) "75.00"
    }
    ["product2"]=>
    object(stdClass)#5067 (2) {
      ["product_id"]=>
      string(4) "9431"
      ["price"]=>
      string(6) "62.00"
    }
  }
  [2]=>
  array(2) {
    ["product1"]=>
    object(stdClass)#5055 (2) {
      ["product_id"]=>
      string(4) "9416"
      ["price"]=>
      string(6) "45.00"
    }
    ["product2"]=>
    object(stdClass)#5057 (2) {
      ["product_id"]=>
      string(4) "9431"
      ["price"]=>
      string(6) "50.00"
    }
  }
  [3]=>
  array(2) {
    ["product1"]=>
    object(stdClass)#5045 (2) {
      ["product_id"]=>
      string(4) "9416"
      ["price"]=>
      string(6) "60.00"
    }
    ["product2"]=>
    object(stdClass)#5047 (2) {
      ["product_id"]=>
      string(4) "9431"
      ["price"]=>
      string(6) "25.00"
    }
  }
}

I need to sort the multi-dimensional array by the total sum of product1 + product2 in each array in ascending order. For example [1] should be above [0] as 75+62 is less than 110 +100.

If anyone can help me with this it would be greatly appreciated.

Hello and welcome to stackoverflow, please also explain in your question what you have tried so far with relevant code and what did not work about this. Please refer to: stackoverflow.com/help/how-to-ask — Sven Hakvoort
– Sven Hakvoort, Commented Oct 12, 2018 at 10:31

Death-is-the-real-truth · Accepted Answer · 2018-10-12 10:50:07Z

3

You can use usort() for this purpose:-

function comparePrice($a,$b)
{
  $a_price = $a['product1']->price + $a['product2']->price;
  $b_price = $b['product1']->price + $b['product2']->price;
  if ($a_price ==$b_price) return 0;
  return ($a_price<$b_price)? -1:1;
}
usort($array,'comparePrice');

A hardcoded working example:- https://3v4l.org/mTfu6

edited Oct 12, 2018 at 10:50

answered Oct 12, 2018 at 10:33

Death-is-the-real-truth

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3 Comments

James D Over a year ago

Thanks for the answer. Not getting much joy with this, getting PHP errors: Undefined property: stdClass::$price I am using CodeIgniter and the array is a database result that could have 5-10 arrays inside it. Would I not need to loop over this usort function somehow?

Death-is-the-real-truth Over a year ago

@JamesD yes then you have to loop inside comparePrice() for calculating two prices. (As you said that array can have n number of prices in it)

Death-is-the-real-truth Over a year ago

@JamesD also i don't have $price in my code , so how's you are getting error related $price if you are using my code

Ty Kroll · Accepted Answer · 2018-10-12 10:37:51Z

0

You need to use user-defined sorting

http://php.net/manual/en/function.usort.php

usort($products, function($a, $b) {
    $prodA = $a['product1']['price'] + $a['product2']['price'];
    $prodB = $b['product1']['price'] + $b['product2']['price'];

    if($prodA == $prodB) return 0;
    return ($prodA < $prodB) ? -1 : 1;
});

answered Oct 12, 2018 at 10:37

Ty Kroll

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Comments

mickmackusa · Accepted Answer · 2018-10-13 15:01:24Z

The php7+ "spaceship operator" (aka three-way-comparison operator) makes the syntax with usort() as clean and brief as possible.

Code: (Demo)

$array = [
    [
        "product1" => (object) ["product_id" => "9416", "price"=>"110.00"],
        "product2" => (object) ["product_id"=>"9431", "price"=>"100.00"]
    ],
    [
        "product1" => (object) ["product_id" => "1254", "price"=>"75.00"],
        "product2" => (object) ["product_id"=>"9431", "price"=>"62.00"]
    ],
    [
        "product1" => (object) ["product_id" => "9416", "price"=>"45.00"],
        "product2" => (object) ["product_id"=>"9431", "price"=>"50.00"]
    ],
    [
        "product1" => (object) ["product_id" => "9416", "price"=>"60.00"],
        "product2" => (object) ["product_id"=>"9431", "price"=>"25.00"]
    ]
];

usort($array, function($a, $b) {
    return $a['product1']->price + $a['product2']->price <=> $b['product1']->price + $b['product2']->price;
});

var_export($array);

Output:

array (
  0 =>                                // sum = 85.00
  array (
    'product1' => 
    (object) array(
       'product_id' => '9416',
       'price' => '60.00',
    ),
    'product2' => 
    (object) array(
       'product_id' => '9431',
       'price' => '25.00',
    ),
  ),
  1 =>                                // sum = 95.00 
  array (
    'product1' => 
    (object) array(
       'product_id' => '9416',
       'price' => '45.00',
    ),
    'product2' => 
    (object) array(
       'product_id' => '9431',
       'price' => '50.00',
    ),
  ),
  2 =>                                // sum = 137.00 
  array (
    'product1' => 
    (object) array(
       'product_id' => '1254',
       'price' => '75.00',
    ),
    'product2' => 
    (object) array(
       'product_id' => '9431',
       'price' => '62.00',
    ),
  ),
  3 =>                                // sum = 210.00 
  array (
    'product1' => 
    (object) array(
       'product_id' => '9416',
       'price' => '110.00',
    ),
    'product2' => 
    (object) array(
       'product_id' => '9431',
       'price' => '100.00',
    ),
  ),
)

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