Sorting PHP arrays holding additional arrays - php

Question

I have an array in PHP which has associative index values as show below. They are irrelevant to the sorting that I need to do, but I need to keep them.
Each value in this array is actually another array which might have 1 to N integers in it, sorted in descending order. However, the integers are written down as text (strings). So the initial data looks something like that:
[10025] => 51, 51, 43, 43, 30, 29, 28, 27, 25, 24, 22, 21
[15671] => 24, 21
[02672] => 24, 26
[76935] => 87, 72, 69, 67, 55, 43, 43, 40, 35, 33, 29
I need to sort this by looking at the maximum value of each secondary array. If the values are equal, I have to look at the second value, etc so finally I'll get something like this:
[76935] => 87, 72, 69, 67, 55, 43, 43, 40, 35, 33, 29
[10025] => 51, 51, 43, 43, 30, 29, 28, 27, 25, 24, 22, 21
[02672] => 24, 26
[15671] => 24, 21
arsort() by default looks at the number of items in each array, which doesn't do the job and raising the SORT_NUMERIC doesn't work either - can't figure out what it does exactly but it doesn't sort the array the way I want.
I've also looked at array_multisort(), however, playing around with it, I couldn't get the desired result either.

Answer 1

Try this, take note of the uasort() function (that's where the magic happens):
<?php
$data = array(
10025 => '51, 51, 43, 43, 30, 29, 28, 27, 25, 24',
15671 => '24, 21',
02672 => '24, 26',
76935 => '87, 72, 69, 67, 55, 43, 43, 40, 35, 33, 29'
); //Inital data array
echo '<pre>'.print_r($data, true).'</pre>'; //Print the array as it is
uasort($data, function($a, $b) { //Sort the array using a user defined function maintaining array indices
$aArray = explode(', ', $a); //Split the strings into proper arrays
$bArray = explode(', ', $b);
rsort($aArray); //Sort the proper arrays from largest to smallest
rsort($bArray);
return $aArray[0] > $bArray[0] ? -1 : 1; //Compare the first element in each array (because it is the largest thanks to the rsort functions)
});
echo '<pre>'.print_r($data, true).'</pre>'; //Print the array in it's new order
?>
Output:
Array
(
[10025] => 51, 51, 43, 43, 30, 29, 28, 27, 25, 24
[15671] => 24, 21
[1466] => 24, 26
[76935] => 87, 72, 69, 67, 55, 43, 43, 40, 35, 33, 29
)
Array
(
[76935] => 87, 72, 69, 67, 55, 43, 43, 40, 35, 33, 29
[10025] => 51, 51, 43, 43, 30, 29, 28, 27, 25, 24
[1466] => 24, 26
[15671] => 24, 21
)

Answer 2

array_multisort() should do the trick:
$yourdata; // your assosiative array with data
$lengths = array();
foreach ($yourdata as $key => $row)
{
$lengths[$key] = $row.length;
}
array_multisort($lengths, SORT_DESC, $yourdata);
Reference url http://www.php.net/manual/ro/function.array-multisort.php

Answer 3

uasort(
$myArray,
function($a, $b) {
$a = explode(',',$a);
$b = explode(',',$a);
$i = 0;
while (true) {
if (isset($a[$i]) && isset($b[$i]) && $a[$i] !== $b[0]) {
return ($a[$i] < $b[$i]) ? -1 : 1;
} elseif (isset($a[$i]) && !isset($b[$i])) {
return 1;
} elseif (isset($b[$i]) && !isset($a[$i])) {
return -1;
} elseif (!isset($b[$i]) && !isset($a[$i])) {
return 0;
}
$i++;
}
}
);