Multidimensional Array Find and Update The Value using PHP

Question

I can't get suitable title for this thread (help me). I can't describe this problem so here the example of my problem.

My array :

Array ( [0] => Array ( [answer] => a [score] => 3 )
[1] => Array ([answer] => b [score] => 4 ) 
[2] => Array ( [answer] => h [score] => 3) 
[3] => Array ( [answer] => a [score] => 4 ))
...

And I wanna get an output like this :

Array ( [0] => Array ( [answer] => a [score] => 7 )
[1] => Array ([answer] => b [score] => 4 ) 
[2] => Array ( [answer] => h [score] => 3))
...

You can see a change of score subkey in index key 0. This is happen because there is two value 'a' in answer subkey from index key 0 and 3. The score changed to 7 because of the sum of both (3+4). Really I don't have an idea for this, sorry for my english and thanks for help. Feel free to comment. :)

Answer 1

$merged = array();

foreach ($array as $answer) {
    if (isset($merged[$answer['answer']])) {
        $merged[$answer['answer']]['score'] += $answer['score'];
    } else {
        $merged[$answer['answer']] = $answer;
    }
}

var_dump($merged);

Answer 2

Check this answer, not using loop :

$arr  = array ( array ( 'answer' => 'a', 'score' => 3 ),
                array ( 'answer' => 'b', 'score' => 4 ), 
                array ( 'answer' => 'h', 'score' => 3), 
                array ( 'answer' => 'a', 'score' => 4 ));

$t = array_reduce($arr, function($result, $item) {
        if(array_key_exists($item['answer'],$result)){
           $result[$item['answer']]    = array('answer' => $item['answer'], 'score' => $item['score']+$result[$item['answer']]['score']);
        }
        else{
           $result[$item['answer']]    = array('answer' => $item['answer'], 'score' => $item['score']);
        }
    return $result;
},array()); 

echo "<pre>";
print_r($t);

Output :

Array
(
    [a] => Array
        (
            [answer] => a
            [score] => 7
        )

    [b] => Array
        (
            [answer] => b
            [score] => 4
        )

    [h] => Array
        (
            [answer] => h
            [score] => 3
        )

)

Answer 3

I though of using a temporary array:

/* Current array */
$array = array(
    array("answer" => "a", "score" => 3),
    array("answer" => "b", "score" => 4),
    array("answer" => "h", "score" => 3),
    array("answer" => "a", "score" => 4)
);

/* Using a temporary array */
$tmp_array = array();
foreach($array as $subarray){
    if(array_key_exists($subarray["answer"], $tmp_array)){
        $tmp_array[$subarray["answer"]] += $subarray["score"];
    }else{
        $tmp_array[$subarray["answer"]] = $subarray["score"];
    }
}

/* Creating a new formatted array */
$new_array = array();
foreach($tmp_array as $key => $value){
    $new_array[] = array("answer" => $key, "score" => $value);
}

print_r($new_array);