按其他數組定義的順序對數組排序

Question

PHP是否有能力按照由另一個數組（B）定義的順序對項目數組（A）進行排序？例如。在首先出現在B中的項目決定哪些項目應該先整理A.當

$order_to_sort_by = array("Gold", "Silver", "Bronze"); 
$items_to_sort = array("Bronze", "Silver", "Bronze", "Gold", "Bronze", "Silver"); 

some_sort_function($items_to_sort, $order_to_sort_by); 

結果：

Gold 
Silver 
Silver 
Bronze 
Bronze 
Bronze 

編輯：有人建議重複似乎用另一個數組的鍵來確定應使用數組中的哪些鍵進行排序。有點不清楚，但我不認爲它是重複的。

Answer 1

你可以嘗試這樣的事情

$order_to_sort_by = array("Gold", "Silver", "Bronze"); 
$items_to_sort = array("Bronze", "Silver", "Bronze", "Gold", "Bronze", "Silver"); 

$order_to_sort_by_reversed = array_flip($order_to_sort_by); 
$sortByArray = function($a, $b) use ($order_to_sort_by_reversed) 
{ 
    return $order_to_sort_by_reversed[$a] - $order_to_sort_by_reversed[$b]; 
}; 
usort($items_to_sort, $sortByArray); 

var_dump($items_to_sort); 

Answer 2

可以使用usort功能來定義如何比較數組的元素。例如：

$order_to_sort_by = array("Gold", "Silver", "Bronze"); 
$items_to_sort = array("Bronze", "Silver", "Bronze", "Gold", "Bronze", "Silver"); 

usort(
    // What to sort. Input array will be changed! 
    $items_to_sort, 

    // Lets define comparing function inplace 
    // ...just cause we can use anonymous functions: 
    function($a, $b) use ($order_to_sort_by) { 
     // Find position of two comparing elements 
     // ...in our ranking array to find what element 
     // ...is 'greater' than another 
     $a_pos = array_search($a, $order_to_sort_by); 
     $b_pos = array_search($b, $order_to_sort_by); 

     // 0 means that items will not be swapped 
     // 1 for moving $b up 
     // -1 for moving $b down 
     if ($a_pos == $b_pos) { 
      return 0; 
     } else if ($a_pos > $b_pos) { 
      return 1; 
     } else { 
      return -1; 
     } 

     // I hope in php7 it would be able 
     // to use `spaceship` operator in this case 
     // instead of these if`s: 
     //  return $a <=> $b 
    } 
); 

var_dump($items_to_sort);