Sorting a multidimensional array by value

Question

Hello. Leafing through foreach (products as product) I have on the page a lot of products like this:

  [2] => Array ( [product_id] => 295 [viewed] => Array ( [0] => Array ( [chat_id] => 74 [message_id] => 162 [status] => 0 ) [1] => Array ( [chat_id] => 74 [message_id] => 163 [status] => 1 ) ) )

In SQL, sorting is not possible.

How can I do a sorting, so that goods where there is [status] => 0 are at the top of the list?

In other words, if there is at least one unread message in the chat, pick it up at the top of the list.

Accepted Answer · 2016-12-08T09:06:04

 usort($products, function($a) { foreach ($a["viewed"] as $viewed) if (!$viewed["status"]) return 0; return 1; });

Description, as requested:

usort($products, function($a, $b) { ... }); allows you to sort an array using a user-defined function to which the first two indices of this array ( $a and $b ) are passed, the second of which is not required in this case. The returned values of the user-defined function determine the order in which the element $a will be displayed.

@ultimatum, but in principle it is not needed in this case, I think so.
The order of the output has not changed, there are no errors.
if at least in one element of the views array the status is zero, then put the product at the top of the list?
that's right. (in other words, if there is at least one unread message in the chat, take it up to the top of the list)

rjhdby rjhdby 12.7k four 22 45 · Answer 2 · 2016-12-08T10:15:53

 //Сортируем сообщения внутри "viewed" foreach($products as &$product){ usort($product['viewed'], function($a,$b){ if($a["status"] < $b['status']) return 1; if($a["message_id"]==$b["message_id"])return 0; //Если они не могут быть равными, то можно удалить эту строку return $a["message_id"]<$b["message_id"]; }); } //Сортируем $products по статусам вложенных сообщений. Внутри viewed мы уже отсортировали usort($products, function($a,$b){return $a["viewed"][0]<$b["viewed"][0];})

not quite, changes the sorting, not all NEW at the top. I leave the accepted answer, because He shorter and correctly fulfills. Senks. - ultimatum

Answer 3 · 2016-12-08T08:58:55

Crutch option, mb someone will come up with smarter, but still:

 $status_array = array(//Массив, в который мы будем записывать товары 0 => array(), 1 => array() ) foreach($products as $product){ $zero_status = false;//Если мы так и не найдем НОВЫЕ записи(статус==0) foreach($product[viewed] as $prod_detail){ $status = $prod_detail[status]; //получаем статус текущего товара(?) if($status == 0){ $status_array[0][] = $product; //записываем его в соответствующий массив $zero_status = true; break;//Искомое условие мы нашли, выходим } } if(!zero_status){ $status_array[1][] = $product; } } $status_array = array_merge($status_array[0],$status_array[1]); //получаем общий массив, где сначала идут записи со status = 0

there may be a dozen or more of them within the same product
but not correctly, displays only those products where there is NEW.
not quite doing a bunch of duplicates + pulls 1 product from [0]

Sorting a multidimensional array by value

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