如何在保留所有唯一键/值的同时合并多维数组？

Question

is there are in build php function or I have to write my own one to merge two multidimensional arrays like that

$list1 = array("school1" => array('string1','string2'));

$list2 = array("school1" => array('string1','string3'),
               "school2" => array('string1','string4','string5')
         );

into array where nothing will be overwritten or omitted. I want to have only unique values in the the 'second array'. Meaning that array school1 will contain string string1 once only

Array ( [school1] => Array ( [0] => string3 [1] => string2 [2] => string1 ) 
        [school2] => Array ( [0] => string5 [1] => string4 [2] => string1 ) ) 

ideal would be if I can have the second array = string1, string2 .... sorted desc

Answer 1

my solution

function merge_db_lists ($list1, $list2) {
  $final_array = array();
  $final_array = go_through_list($list1, $final_array);
  $final_array = go_through_list($list2, $final_array);
  return $final_array;
}   

function go_through_list($list,$output){
  foreach (array_keys($list) as $key){
    if (array_key_exists($key, $output)){
      foreach ($list[$key] as $item ){
        $output[$key][] = $item;
      }  
      arsort($output[$key]);
    }
    else{
      $output[$key] = $list[$key];
    }  
  }
  return $output;
}