Array_map when elements are shuffled - php

Question

I have this array (it's just a part of it). 6 = question ID, optionIDs = possible answers.
Array
(
[3] => Array
(
[0] => 6
[1] => Array
(
[0] => Array
(
[optionID] => 16
[isCorrect] => 0
)
[1] => Array
(
[optionID] => 14
[isCorrect] => 1
)
[2] => Array
(
[optionID] => 15
[isCorrect] => 0
)
[3] => Array
(
[optionID] => 17
[isCorrect] => 0
)
)
)
[7] => Array
(
[0] => 6
[1] => Array
(
[0] => Array
(
[optionID] => 16
[isCorrect] => 0
)
[1] => Array
(
[optionID] => 15
[isCorrect] => 0
)
[2] => Array
(
[optionID] => 17
[isCorrect] => 0
)
[3] => Array
(
[optionID] => 14
[isCorrect] => 1
)
)
)
)
I'm trying to merge redundant questions (6 and 6) with array_map:
$unique = array_map('unserialize', array_unique(array_map('serialize', $quizQuestionArray)));
And it works as long as optionIDs are in the same order. But in some cases (like here) they are shuffled (16,14,15,17) (16,15,17,14). Is there a way to keep them shuffled and remove duplicate questions?

Answer 1

array_map-serialize is a pretty crude way to deduplicate an array. You should be using something like this instead:
$dupeIds = [];
$array = array_filter($array, function ($item) use (&$dupeIds) {
$keep = !isset($dupeIds[$item[0]]);
$dupeIds[$item[0]] = true;
return $keep;
});

Answer 2

You will need to sort them to the same order before applying you array_map() function. You can use the uasort() function and supply your own comparison function like this:
// Example array
$array = array(
3 => array(
0 => 6,
1 => array(
0 => array(
'optionID' => 16,
'isCorrect' => 0
),
1 => array(
'optionID' => 14,
'isCorrect' => 1
),
2 => array(
'optionID' => 15,
'isCorrect' => 0
),
3 => array(
'optionID' => 17,
'isCorrect' => 0
),
)
),
7 => array(
0 => 6,
1 => array(
0 => array(
'optionID' => 16,
'isCorrect' => 0
),
1 => array(
'optionID' => 15,
'isCorrect' => 0
),
2 => array(
'optionID' => 17,
'isCorrect' => 0
),
3 => array(
'optionID' => 14,
'isCorrect' => 1
),
)
)
);
// You can supply parts of an array to uasort()
// uasort() will modify your array but keep your keys.
uasort($array[3][2], 'sort_by_optionid');
uasort($array[7][3], 'sort_by_optionid');
function sort_by_optionid($a, $b) {
if ($a['optionID'] === $b['optionID']) {
return 0;
} else if ($a['optionID'] > $b['optionID']) {
return 1;
} else {
return -1;
}
}
// Done.
Now the keys are preserved and you can easily array_map() to find the duplicates and then sort again back to the original state according to the keys. E.g. with uksort()