Multidimensional Array Find and Update The Value using PHP - 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);