Sorting 2-dimensional array in descending order keeping original indexes

I need to sort 2-dimensional array in descending order keeping original indexes:

$arr = array();

for ($i=0; $i<5; $i++) {
    $arr[] = array(rand(0,5), rand(10,100));
}

The result must be something like this:

[0] => array(5, 100)
[1] => array(5, 90)
[2] => array(5, 35)
[3] => array(4, 10)
[4] => array(3, 15)

So, firstly, the array is sorted with respect to the 1st column, and, secondly it is sorted with respect to the 2nd column.

The function arsort works with vectors, if I understand it correctly.

How can I solve this task?

Answers

see http://docs.php.net/uasort

e.g.

<?php
$arr = array(
    'A'=>array(5, 100),
    'B'=>array(4, 10),
    'C'=>array(5, 35),
    'D'=>array(3, 15),
    'E'=>array(5, 90)
);

uasort($arr, function($a, $b) {
    if ( $a[0] < $b[0] ) return 1;
    else if ( $a[0] > $b[0] ) return -1;
    else if ( $a[1] < $b[1] ) return 1;
    else if ( $a[1] > $b[1] ) return -1;
    else return 0;
});

foreach($arr as $k=>$v) {
    echo $k,'=', join(', ', $v), "\n";
}

prints

A=5, 100
E=5, 90
C=5, 35
B=4, 10
D=3, 15

Need Your Help