Sorting multi-dimensional array by weighted value

You might not want a global variable, but you need something that behaves like one. You could use a class with static methods and parameters. It won't pollute the global scope that much and it would still function the way you need it.

class CountryCompare {
    public static $country_priorities;

    public static function compare( $a, $b ) {
        // Some custom sorting criteria
        // Work with self::country_priorities
    }

    public static function sort( $countries ) {
        return usort( $countries, array( 'CountryCompare', 'compare' ) );
    }
}

Then just call it like this:

CountryCompare::country_priorities = loadFromConfig();
CountryCompare::sort( $countries );

You can use closures (PHP >= 5.3):

$weights = array( ... );
usort($records, function($a, $b) use ($weights) {
    // use $weights in here as usual and perform your sort logic
});

See Demo : http://codepad.org/vDI2k4n6

$arrayMonths = array(
       'jan' => array(1, 8, 5,4),
       'feb' => array(10,12,15,11),
       'mar' => array(12, 7, 4, 3),
       'apr' => array(10,16,7,17),
    );

$position = array("Foo1","Foo2","Foo3","FooN");
$set = array();

foreach($arrayMonths as $key => $value)
{
    $max = max($value);
    $pos = array_search($max, $value);
    $set[$key][$position[$pos]] = $max ;
}


function cmp($a, $b)
{
    foreach($a as $key => $value )
    {
        foreach ($b  as $bKey => $bValue)
        {
            return $bValue - $value ;
        }
    }

}

uasort($set,"cmp");
var_dump($set);

output

array
      'apr' => 
        array
          'FooN' => int 17
      'feb' => 
        array
          'Foo3' => int 15
      'mar' => 
        array
          'Foo1' => int 12
      'jan' => 
        array
          'Foo2' => int 8

another example:-

Sorting a Multi-Dimensional Array with PHP

http://www.firsttube.com/read/sorting-a-multi-dimensional-array-with-php/

Every so often I find myself with a multidimensional array that I want to sort by a value in a sub-array. I have an array that might look like this:

//an array of some songs I like
$songs =  array(
        '1' => array('artist'=>'The Smashing Pumpkins', 'songname'=>'Soma'),
        '2' => array('artist'=>'The Decemberists', 'songname'=>'The Island'),
        '3' => array('artist'=>'Fleetwood Mac', 'songname' =>'Second-hand News')
    );

The problem is thus: I’d like to echo out the songs I like in the format “Songname (Artist),” and I’d like to do it alphabetically by artist. PHP provides many functions for sorting arrays, but none will work here. ksort() will allow me to sort by key, but the keys in the $songs array are irrelevant. asort() allows me to sort and preserves keys, but it will sort $songs by the value of each element, which is also useless, since the value of each is “array()”. usort() is another possible candidate and can do multi-dimensional sorting, but it involves building a callback function and is often pretty long-winded. Even the examples in the PHP docs references specific keys.

So I developed a quick function to sort by the value of a key in a sub-array. Please note this version does a case-insensitive sort. See subval_sort() below.

function subval_sort($a,$subkey) {
    foreach($a as $k=>$v) {
        $b[$k] = strtolower($v[$subkey]);
    }
    asort($b);
    foreach($b as $key=>$val) {
        $c[] = $a[$key];
    }
    return $c;
}

To use it on the above, I would simply type:

$songs = subval_sort($songs,'artist'); 
print_r($songs);

This is what you should expect see:

Array
(
    [0] => Array
        (
            [artist] => Fleetwood Mac
            [song] => Second-hand News
        )

    [1] => Array
        (
            [artist] => The Decemberists
            [song] => The Island
        )

    [2] => Array
        (
            [artist] => The Smashing Pumpkins
            [song] => Cherub Rock
        )

)

The songs, sorted by artist.

The answer to your question is indeed in the usort() function. However, what you need to do is write the function that you pass to it is doing the weighting for you properly.

Most of the time, you have something like

if($a>$b)
{
    return $a;
}

But what you need to do is something along the lines of

if($a>$b || $someCountryID != 36)
{
    return $a;
}
else
{
    return $b;
}

You need to use ksort to sort by weight, not usort. That will be much cleaner.

Arrange your data in an associative array $weighted_data in the format weight => country_data_struct. This is a very intuitive form of presentation for weighted data. Then run

krsort($weighted_data)