Sorting PHP arrays holding additional arrays

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.

OdinX · Accepted Answer · 2014-05-20 21:38:45Z

2

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
)

answered May 20, 2014 at 21:38

OdinX

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3 Comments

mmvsbg Over a year ago

Thank you, that's a good tip. I have a question though. You stated $aArray[0] > $bArray[0] etc. If they are equal, does it automatically go to check the first index, then the second and so on?

OdinX Over a year ago

Not as it currently stands, it just looks for the first number, it wouldn't be too hard to change it though, a simple loop would do it.

mmvsbg Over a year ago

Yes, a little more research showed exactly the same thing. Thank you!

Adrian Toma · Accepted Answer · 2014-05-20 21:33:06Z

0

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

answered May 20, 2014 at 21:33

Adrian Toma

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Comments

Mark Baker · Accepted Answer · 2014-05-20 21:38:47Z

0

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++;
        }
    }
);

edited May 20, 2014 at 21:38

answered May 20, 2014 at 21:31

Mark Baker

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