PHP: uksort - Manual

uksort

skippy at zuavra dot net
28-Nov-2005 03:57


As silly as it may seem, you may sometimes need a comparison function which leaves the array in the same order. It's not as trivial as returning 0 (zero) all the time, since for some reason it doesn't actually leave the values alone.



Here's a simpler and faster version of the code presented by Ignatius Reilly in an earlier note, which can be used to infer original position based on the original array:



function cmp($a, $b) {

  if ($a == $b) return 0;

  global $target_array_here;

  static $keys;

  if (!$keys) $keys = array_keys($target_array_here);

  $x = array_search($a, $keys);

  $y = array_search($b, $keys);

  return ($x < $y ? -1 : 1);

}

Toni Soler
28-Sep-2005 01:51


Added "sort_type" to the previous class (ascendent/descendent options)



<?php

class t_object_sorter

{

    var $object_array;

    var $sort_by;

    

    function _comp($a,$b)

    {

        $key=$this->sort_by;

        if ($this->object_array[$a]->$key == $this->object_array[$b]->$key) return 0;

        return ($this->object_array[$a]->$key < $this->object_array[$b]->$key) ? -1 : 1;

    }

    

    function _comp_desc($a,$b)

    {

        $key=$this->sort_by;

        if ($this->object_array[$a]->$key == $this->object_array[$b]->$key) return 0;

        return ($this->object_array[$a]->$key > $this->object_array[$b]->$key) ? -1 : 1;

    }

    

    function sort(&$object_array, $sort_by, $sort_type = "ASC")

    {

        $this->object_array = $object_array;

        $this->sort_by      = $sort_by;

        if ($sort_type == "DESC")

        {

            uksort($object_array, array($this, "_comp_desc"));

        }

        else

        {

            uksort($object_array, array($this, "_comp"));

        }

    }

}

?>

Commanace at gmail dot com
27-Aug-2005 09:38


I've written a small class that will sort arrays of objects by a certain attribute:



<?php

class t_object_sorter

{

    protected $object_array;

    protected $sort_by;

    

    private function _comp($a,$b)

    {

        $key=$this->sort_by;

        debug($this->object_array[$a],__FILE__,__LINE__);

        if ($this->object_array[$a]->$key == $this->object_array[$b]->$key) return 0;

        return ($this->object_array[$a]->$key < $this->object_array[$b]->$key) ? -1 : 1;

    }

    

    public function sort(&$object_array, $sort_by)

    {

        $this->object_array = $object_array;

        $this->sort_by      = $sort_by;

        uksort($object_array, array($this, "_comp"));

    }

}

?>



It is used like that:



<?php

$sorter = new t_object_sorter;

$sorter->sort($menu->item, 'position');

?>



This call will sort all "item"-objects of the object "menu" by their attribute "position".



I hope this is helpfull.

Jimomighty
19-Mar-2005 07:30


...



function cmp($a, $b)

{

   if ($a == $b) {

       return 0;

   }

   return ($a < $b) ? -1 : 1;

}



function uksort_tree ( &$array )

{

    // [PHP5] foreach ( $array as &$value )

    foreach ( $array as $key => $value )

    {

       if ( is_array ( $value ) )

       {

            // [PHP5] uksort_tree ( $value );

           uksort_tree ( $array[$key] );

       }

    }



    uksort( $array, "cmp" );

}



uksort_tree( $myEntryArray );



...

aleczapka at gmx dot net
22-Dec-2004 04:35


One remark regarding array_sorter class.

It won't work correctly with eg. dates from mysql like 20041206105350, cause you can't convert such number into integer. To fix it remove intval() from the code. If the variable is a number it will work without converting this to int anyways. Here is the fix.



<?php

....

if ($a == $b) 

    return 0;

if ($this->sasc)

    return ($a > $b) ? 1 : -1;

else

    return ($a > $b) ? -1 : 1;

...

?>

jg at delegation dot ca
17-Dec-2004 07:41


To sort dates with uksort:



function datediff($a, $b) {

    



$a = date('U',$a);

$b = date('U',$b);



if ($a == $b) $r = 0;

else $r = ($a > $b) ? 1: -1;



return $r;

}

aleczapka at gmx dot net
06-Dec-2004 04:27

fabriceb at gmx dot net
08-Jul-2004 06:26


(about sorting an array of objects by their properties in a class - inspired by webmaster at zeroweb dot org at usort function)

I'm using classes as an abstraction for querying records in a database and use arrays of objects to store records that have an 1 to n relationship. E.g. a class "family" has family members stored as an array of objects. Each of those objects prepresents a record in a database related to the family (by it's familyId).



To identify members, I'm using their memberId as the key of the array e.g. $family->members[$memberId].

To sort the family members AFTER fetching them with the database query, you can use the functions _objSort and sortMembers which will sort the "members" array by key using it's properties (for space reasons I didn't include the methods used to open the records):

<?php

class familyMember

{

    var $memberId;

    var $familyId;

    var $firstName;

    var $age;

    var $hairColor;

// ...

}



class family

{

    var $familyId;

    var $name;

    var $members = array(); // array of familyMember objects

    var $sortFields = array();

    var $sortDirections = array();

    // ...

    function _objSort(&$a, &$b, $i = 0)

    {

        $field        = $this->sortFields[$i];

        $direction    = $this->sortDirections[$i];

        

        $diff = strnatcmp($this->details[$a]->$field, $this->details[$b]->$field) * $direction;

        if ($diff == 0 && isset($this->sortFields[++$i]))

        {

            $diff = $this->_objSort($a, $b, $i);

        }

        

        return $diff;

    }

    

    function sortMembers($sortFields)

    {

        $i = 0;

        foreach ($sortFields as $field => $direction)

        {

            $this->sortFields[$i] = $field;

            $direction == "DESC" ? $this->sortDirections[$i] = -1 : $this->sortDirections[$i] = 1;

            $i++;

        }

        

        uksort($this->details, array($this, "_objSort"));

        

        $this->sortFields = array();

        $this->sortDirections = array();

    }

}

// open a family

$familyId = 5;

$family = new family($familyId);

$family->open(); // this will also fetch all members



// sort members by 3 fields

$family->sortMembers(array("firstName" => "ASC", "age" => "DESC", "hairColor" => "ASC"));

// output all family members

foreach ($family->members as $member)

{

    echo $member->firstName." - ".$member->age." - ".$member->hairColor."<br />";

}

?>



Note that this might not be the fastest thing on earth and it hasn't been tested very much yet but I hope it's useful for someone.

jOn
16-Mar-2004 05:57


a quick function to point uksort() at, for sorting by key, but ignoring "the" from any keys that start with it:



<?php

function comp($a,$b)

{

    //remove "the" (case-insensitive), and any non-word

    // characters from any string(s) that start with "the"

    $a = preg_replace('|^the\b\W*|i','',$a);

    $b = preg_replace('|^the\b\W*|i','',$b);



   if ($a == $b) {

       return 0;

   }

   return ($a > $b) ? 1 : -1;

}

?>

webmaster at kik-it at N0SP4M dot com
09-Feb-2004 10:03


The code below allows you to sort an array_A following array_B keys order, original keys and values remain associated.



<?



//main function

Function SortArrayAKeysLikeArrayBKeys(&$TheArrayToSort){

   uksort($TheArrayToSort,"SortArrayAKeysLikeArrayBKeys_cmp");

}



//the custom compare function

Function SortArrayAKeysLikeArrayBKeys_cmp($a,$b){

  global $TheArrayOrder;

  $PosA=KeyPosInArray($a,$TheArrayOrder);

  $PosB=KeyPosInArray($b,$TheArrayOrder);

  if ($PosA==$PosB){return 0;}else{return ($PosA > $PosB ? 1 : -1);}

}



//where is my key in my array

Function KeyPosInArray($Key,$Array){

   $i=0;

   $Pos=99999999;

   if($Array){

      foreach($Array as $K => $V){

         $i++;

         if($K==$Key){

            $Pos=$i;

            break;

         }

      }

   }

   return $Pos;

}



//the array you want to sort

$AnyArrayToSort['age']='19';

$AnyArrayToSort['ville']='rennes';

$AnyArrayToSort['website']='kik-it.com';

$AnyArrayToSort['region']='bretagne';

$AnyArrayToSort['code_postal']='35200';

$AnyArrayToSort['Nom']='Fred';



//the array with the correct keys/values order

$TheArrayOrder['Nom']='Whatever';

$TheArrayOrder['age']='Anything';

$TheArrayOrder['region']='What u want';

$TheArrayOrder['ville']='Something';

$TheArrayOrder['code_postal']='Nothing';



//before sort

print_r($AnyArrayToSort);    

echo "<br>";

//we sort

SortArrayAKeysLikeArrayBKeys($AnyArrayToSort);

echo "<br>";

//after sort

print_r($AnyArrayToSort);

?>



Will print :



Array ( [age] => 19 [ville] => rennes [website] => kik-it.com [region] => bretagne [code_postal] => 35200 [Nom] => Fred ) 



Array ( [Nom] => Fred [age] => 19 [region] => bretagne [ville] => rennes [code_postal] => 35200 [website] => kik-it.com ) 



The keys not listed in the $TheArrayOrder will appear at the end of your sorted array (only if Key Pos < 99999999 ;o)

guss at typo dot co dot il
07-Dec-2003 12:18


Regarding the recursive sorting function above:

Genrally speaking, any recursion can be reimplemented using simple iteration. in the specific case, using recursion to compare strings has a huge performance impact while a simple loop would suffice and be faster and more simple. 

Recursion is only good if it simplifies your code or your understanding of the concept. the previous example does neither, especially as it does a lot of repetitive things in each iteration, such as asigning the character order constant, rebuilding it into an array and such



For example, the string comparison could be written as such : 

function str_compare($a,$b) {

    $order="aA��bBcC&#269;&#268;..."; // longer normally & without that html entities

    $default = strlen($a) - strlen($b);

    $minlen = strlen($a) < strlen($b) ? strlen($a) : strlen($b);

    for ($i = 0; $i < $minlen; $i++) {

        $pos_a=strpos($order,$a[$i]);

        $pos_b=strpos($order,$b[$i]);

        if ($pos_a != $pos_b)

            return $pos_a - $pos_b;

    }

    return $default;

}



Which is much simpler and faster.

Note that the above function will break for characters that are not listed in $order. it should be failry trivial to fix it.

ignatius dot reilly at free dot fr
13-Nov-2003 10:59


To use a more complicated comparison function, one can use a callback to a method of an object instance.

For example the following will take an array $arr whose keys are the same as those of $reference, and reorder $arr so that the keys appear in the same order as in $reference.



class kcmp {

    var $reference ;

    function kcmp( $reference ) {

       $this->reference = $reference ; 

    }

    function kcompare( $a, $b ) {

       $keys = array_keys( $this->reference ) ;

       $position_a = array_search( $a, $keys ) ;

       $position_b = array_search( $b, $keys ) ;

       return  $position_a < $position_b ? -1 : 1 ;    

    }

}



$reference = array(

    "k2" => "a2",

    "k3" => "a3",

    "k1" => "a1"

) ;

$arr = array(

    "k1" => "b1",

    "k2" => "b2",

    "k3" => "b3"

) ;

print_r( $arr ) ; 

uksort( $arr, array( new kcmp( $reference ), "kcompare" ) ) ;

print_r( $arr ) ;

pachollini at stones dot com
03-Mar-2003 04:47


I tried to write my own function for sorting with special Czech characters, which php normally compares wrong way. The function is recoursive, it compares the first characters of the strings and when they're the same, the function calls itself with parameters without the first character. My php often crashed by calling this function. After some time if found the problem: it crashed after 10th recoursive call. I think it's a bug in php, and I've made this workaround:



function str_compare($a,$b,$level=0)

    {

    $maxlevel=9;

    if($GLOBALS["STR_COMPARE"] && is_array($a))

        {

        $a=$a[$GLOBALS["STR_COMPARE"]];

        $b=$b[$GLOBALS["STR_COMPARE"]];

        }

    $result=0;

    if($a==$b) return 0;

    elseif($a=="") return ($b=="") ? 0 : 1;

    elseif ($b=="") return -1;

    else

        {

        $order="aA��bBcC&#269;&#268;..."; // longer normally & without that html entities

        for($i=0;$i<strlen($order);$i++) $codes[]=ord($order[$i]);

        $char_a=$a[0];$char_b=$b[0];

        $pos_a=array_search(ord($a),$codes); $pos_b=array_search(ord($b),$codes);

        //echo"$char_a - $pos_a<br>";

        if($pos_a===false || $pos_b===false)

            {

            if($char_a==$char_b) 

                {

                if ($level<=$maxlevel) $result=str_compare (substr($a,1),substr($b,1),$level+1);

                else $a<$b ? $result=-1 : $result=1;

                }

            else ($char_a<$char_b) ? $result=-1 : $result=1;

            }

        else

            {

            if($pos_a==$pos_b) 

                {

                if ($level<=$maxlevel) $result=str_compare(substr($a,1), substr($b,1),$level+1);

                else $a<$b ? $result=-1 : $result=1;

                }

            else ($pos_a<$pos_b) ? $result=-1 : $result=1;

            }

        return $result;

        }

    }

kumar at chicagomodular (dot) com
29-Jan-2003 09:12


The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

--necessary info from manual/en/function.usort.php if you didn't see it already

uksort

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