PHP Multidimensional Array Sort & Trim - php

Question

I have the array below. I do not know how I can sort secondary array so elements with highest value gets to be first and I want to trim if the array length is more than 20 elements. I want first dimension to be sorted by alphabetical, secondary dimension to be sorted by values and if there are more than 20 entries, I want only first 20 highest value.
(
[a] => Array
(
[option1] => 2
[option2] => 3
[option3] => 1
[option4] => 7
[option5] => 8
[option6] => 3
[option7] => 2
[option8] => 32
[option9] => 35
[option10] => 33
[option11] => 32
[option12] => 35
[option13] => 37
[option14] => 3
[option15] => 39
[option16] => 4
[option17] => 36
[option18] => 31
[option19] => 12
[option20] => 35
[option21] => 3
[option22] => 32
[option23] => 31
)
[b] => Array
(
[option16] => 4
[option17] => 36
[option18] => 31
[option19] => 12
)

Answer 1

Php has everything for you!
<?php
$array = array(
'b' => array(
'option1' => 33,
'option2' => 12,
'option3' => 17,
'option4' => 44,
'option5' => 543,
'option6' => 56,
'option7' => 8,
'option8' => 0,
'option9' => -10,
'option10' => 234,
'option11' => 67,
'option12' => 99,
'option13' => 3363,
'option14' => 912,
'option15' => 51,
'option16' => 42,
'option17' => 105,
'option18' => 80,
'option19' => 44,
'option20' => 0,
'option21' => 15,
),
'a' => array(
'option1' => 88,
'option2' => 0,
'option3' => -23,
'option4' => 16,
'option5' => 76,
),
);
// sorts array keys alphabetically
ksort($array, SORT_NATURAL);
// iterrate each key (a or b etc.) => value (value is assoc array of options) pair
foreach ($array as $k => &$v) {
// reverse sort (from max to min) options by its value
// with preserve keys
arsort($v);
// cut options array to max 20 element
$v = array_slice($v, 0, 20);
}
echo '<pre>' . print_r($array, 1) . '</pre>';
Online runnable.