Используйте этот код и посмотрите на мои комментарии в коде:
// Generate array having 20 numbers from 1 to 20
$range = range(1, 20);
// Change the order of elements
shuffle($range);
// Split array into 4 chunks each having 5 elements
$unsorted = array_chunk($range, 4);
// Copy original array
$sorted = $unsorted;
// Sort copied array
array_walk($sorted, 'sort');
Теперь у вас есть 2 массива с одинаковыми элементами, но один массив отсортирован:
print_r($unsorted);
// prints:
Array
(
[0] => Array
(
[0] => 14
[1] => 10
[2] => 3
[3] => 9
)
[1] => Array
(
[0] => 8
[1] => 7
[2] => 19
[3] => 16
)
[2] => Array
(
[0] => 11
[1] => 20
[2] => 5
[3] => 12
)
[3] => Array
(
[0] => 15
[1] => 4
[2] => 2
[3] => 18
)
[4] => Array
(
[0] => 17
[1] => 6
[2] => 1
[3] => 13
)
)
print_r($sorted);
Array
(
[0] => Array
(
[0] => 3
[1] => 9
[2] => 10
[3] => 14
)
[1] => Array
(
[0] => 7
[1] => 8
[2] => 16
[3] => 19
)
[2] => Array
(
[0] => 11
[1] => 12
[2] => 20
[3] => 5
)
[3] => Array
(
[0] => 2
[1] => 4
[2] => 15
[3] => 18
)
[4] => Array
(
[0] => 1
[1] => 6
[2] => 13
[3] => 17
)
)