sort

(PHP 4, PHP 5, PHP 7)

sort — Sort an array

Description

bool sort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

This function sorts an array. Elements will be arranged from lowest to highest when this function has completed.

Parameters

array

The input array.

sort_flags

The optional second parameter sort_flags may be used to modify the sorting behavior using these values:

Sorting type flags:

SORT_REGULAR - compare items normally (don't change types)
SORT_NUMERIC - compare items numerically
SORT_STRING - compare items as strings
SORT_LOCALE_STRING - compare items as strings, based on the current locale. It uses the locale, which can be changed using setlocale()
SORT_NATURAL - compare items as strings using "natural ordering" like natsort()
SORT_FLAG_CASE - can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively

Return Values

Returns TRUE on success or FALSE on failure.

Changelog

Version	Description
5.4.0	Added support for `SORT_NATURAL` and `SORT_FLAG_CASE` as `sort_flags`
5.0.2	Added `SORT_LOCALE_STRING`

Examples

Example #1 sort() example


<?php

$fruits = array("lemon", "orange", "banana", "apple");
sort($fruits);
foreach ($fruits as $key => $val) {
    echo "fruits[" . $key . "] = " . $val . "\n";
}

?>

The above example will output:

fruits[0] = apple
fruits[1] = banana
fruits[2] = lemon
fruits[3] = orange

The fruits have been sorted in alphabetical order.

Example #2 sort() example using case-insensitive natural ordering


<?php

$fruits = array(
    "Orange1", "orange2", "Orange3", "orange20"
);
sort($fruits, SORT_NATURAL | SORT_FLAG_CASE);
foreach ($fruits as $key => $val) {
    echo "fruits[" . $key . "] = " . $val . "\n";
}

?>

The above example will output:

fruits[0] = Orange1
fruits[1] = orange2
fruits[2] = Orange3
fruits[3] = orange20

The fruits have been sorted like natcasesort().

Notes

Note: This function assigns new keys to the elements in array. It will remove any existing keys that may have been assigned, rather than just reordering the keys.

Note: Like most PHP sorting functions, sort() uses an implementation of » Quicksort. The pivot is chosen in the middle of the partition resulting in an optimal time for already sorted arrays. This is however an implementation detail you shouldn't rely on.

Warning

Be careful when sorting arrays with mixed types values because sort() can produce unpredictable results.

User Contributed Notes

phpdotnet at m4tt dot co dot uk

5 years ago

Walter Tross

4 years ago


unless you specify the second argument, "regular" comparisons will be used. I quote from the page on comparison operators:
"If you compare a number with a string or the comparison involves numerical strings, then each string is converted to a number and the comparison performed numerically."
What this means is that "10" < "1a", and "1a" < "2", but "10" > "2". In other words, regular PHP string comparisons are not transitive.
This implies that the output of sort() can in rare cases depend on the order of the input array:
<?php
function echo_sorted($a)
{
   echo "{$a[0]} {$a[1]} {$a[2]}";
   sort($a);
   echo " => {$a[0]} {$a[1]} {$a[2]}\n";
}
// on PHP 5.2.6:
echo_sorted(array( "10", "1a", "2")); // => 10 1a 2
echo_sorted(array( "10", "2", "1a")); // => 1a 2 10
echo_sorted(array( "1a", "10", "2")); // => 2 10 1a
echo_sorted(array( "1a", "2", "10")); // => 1a 2 10
echo_sorted(array( "2", "10", "1a")); // => 2 10 1a
echo_sorted(array( "2", "1a", "10")); // => 10 1a 2
?>

otobrglez at gmail dot com

7 years ago


This will select number of unique keys from array and order them in original order.

<?php
/*
$rows - array of records
$st - number of keys that you want to have

By Oto Brglez.

*/

$pom_k = array();
for($i=0; $i<$st;){
    $pom = array_rand($rows,1);
    if(!in_array($pom,$pom_k)){
        $pom_k[] = $pom;
        $i++;
    };
};
sort($pom_k,SORT_NUMERIC);

?>

matpatnik at hotmail dot com

8 years ago


This function will sort entity letters eg:&eacute;

I hope that help someone

function sort_entity($array) {
    $total = count($array);
    for ($i=0;$i<$total;$i++) {
        if ($array[$i]{0} == '&') {
            $array[$i] = $array[$i]{1}.$array[$i];
        } else {
            $array[$i] = $array[$i]{0}.$array[$i];
        }
    }
    sort($array);
    
    for ($i=0;$i<$total;$i++) {
        $array[$i] = substr($array[$i],1);
    }
    
    return $array;
}

stepmuel at ee dot ethz dot ch

7 years ago


A little shorter way to sort an array of objects; with a callback function.

<?php 
function objSort(&$objArray,$indexFunction,$sort_flags=0) {
    $indices = array();
    foreach($objArray as $obj) {
        $indeces[] = $indexFunction($obj);
    }
    return array_multisort($indeces,$objArray,$sort_flags);
}

function getIndex($obj) {
    return $obj->getPosition();
}

objSort($objArray,'getIndex'); 
?>

james at miicro dot net

10 years ago


It's useful to know that if you're using this function on a multidimensional array, php will sort the first key, then the second and so on. This is similar to being able to use SQL to order by field1, field2 etc.

So:

Array ( 
[0] => Array ( [category] => work [name] => Smith ) 
[1] => Array ( [category] => play [name] => Johnson ) 
[2] => Array ( [category] => work [name] => Berger )
)

will become:

Array ( 
[0] => Array ( [category] => play [name] => Johnson )
[1] => Array ( [category] => work [name] => Berger ) 
[2] => Array ( [category] => work [name] => Smith ) 
)

Hope it helps someone.

joris at mangrove dot nl

9 years ago


Commenting on note http://www.php.net/manual/en/function.sort.php#62311 :

Sorting an array of objects will not always yield the results you desire.

As pointed out correctly in the note above, sort() sorts the array by value of the first member variable. However, you can not always assume the order of your member variables! You must take into account your class hierarchy!

By default, PHP places the inherited member variables on top, meaning your first member variable is NOT the first variable in your class definition! 
However, if you use code analyzers or a compile cache, things can be very different. E.g., in eAccelerator, the inherited member variables are at the end, meaning you get different sort results with caching on or off.

Conclusion:
Never use sort on arrays with values of a type other than scalar or array.

aditycse at gmail dot com

8 months ago


/*
 * Name : Aditya Mehrotra 
 * Email: aditycse@gmail.com
 */
//Example for sorting by values for an alphanumeric array also having case-sensitive data
$exampleArray1 = $exampleArray2 = array(
    0 => 'example1',
    1 => 'Example10',
    2 => 'example12',
    3 => 'Example2',
    4 => 'example3',
    5 => 'EXAMPLE10',
    6 => 'example10'
);

//default sorting
asort($exampleArray1);

// alphanumeric with case-sensitive data sorting by values
asort($exampleArray2, SORT_STRING | SORT_FLAG_CASE | SORT_NATURAL);

//output of defaut sorting
print_r($exampleArray1);
/*
 * output of default sorting
  Array
  (
  [5] => EXAMPLE10
  [1] => Example10
  [3] => Example2
  [0] => example1
  [6] => example10
  [2] => example12
  [4] => example3
  )
 */

print_r($exampleArray2);
/*
 * output of alphanumeric with case-sensitive data sorting by values
 Array
(
    [0] => example1
    [3] => Example2
    [4] => example3
    [5] => EXAMPLE10
    [1] => Example10
    [6] => example10
    [2] => example12
)
 */

me[ at ]szczepan[ dot ]info

3 years ago


Sorting the keys, but keep the values in order is not possible by just ordering, because it would result in a new array. This is also the solution: Create a new array

<?php
$a = array(9=>"a",8=>"c",5=>"d");

$keys = array_keys($a);
sort($keys);
$result = array_combine($keys, array_values($a));

//Result : array(5=>"a",8=>"c",9=>"d");
?>

eriewave at hotmail dot com

6 years ago


If you need to sort an array containing some equivalent values and you want the equivalents to end up next to each other in the overall order (similar to a MySQL's ORDER BY output), rather than breaking the function, do this:

<?php

sort($array, ksort($array))

?>

-When the sort() function finds two equivalents, it will sort them arbitrarily by their key #'s as a second parameter.

-Dirk

williamprogphp at[pleaseNOTSPAM] yahoo d

2 years ago


In order to make some multidimensional quick sort implementation, take advantage of this stuff

<?php
        function quickSortMultiDimensional($array, $chave) {
            if( count( $array ) < 2 ) {
                return $array;
            }
            $left = $right = array( );
            reset( $array );
            $pivot_key    = key( $array );
            $pivot    = array_shift( $array );
            foreach( $array as $k => $v ) {
                if( $v[$chave] < $pivot[$chave] )
                        $left[$k][$chave] = $v[$chave];
                else
                        $right[$k][$chave] = $v[$chave];
            }
            return array_merge(
                                    quickSortMultiDimensional($left, $chave), 
                                    array($pivot_key => $pivot), 
                                    quickSortMultiDimensional($right, $chave)
            );            
        }
?>

I make it using the idea from pageconfig dot com

tks for viewing

Brecht Cloetens

6 years ago


<?php
    
/**
 * function: array_columns
 * author: Brecht Cloetens
 * params: $a = array() // original array
 *         $c = int() // number of columns
 */
function array_columns(&$a, $c=2)
{
    $m = ceil(count($a)/$c);
    $j = 0;
    for($i=0; $i<$m; $i++) {
        for($k=0; $k<$c; $k++) {
            $key = $i+($m*$k);
            settype($key,'integer');
            if(array_key_exists($key,$a)) {
                $b[$j] = $a[$key];
                $j++;
            }
        }
    }
    $a = $b;
}

$arr = range('a','z');
array_columns($arr,4);
print_r($arr);

?>

Example:
array(1,2,3,4,5) will be converted to array(1,4,2,5,3);

This can be easy if you want to display an array into a specified number of columns.

<table>
    <tr>
        <td>$arr[0] => 1</td>
        <td>$arr[1] => 4</td>
    </tr>
    <tr>
        <td>$arr[2] => 2</td>
        <td>$arr[3] => 5</td>
    </tr>
    <tr>
        <td>$arr[4] => 3</td>
        <td></td>
    </tr>
</table>

alex [at] vkpb [dot] com

9 years ago


Sorting of an array by a method of inserts.

<?

  
       function sortByField($multArray,$sortField,$desc=true){
            $tmpKey='';
            $ResArray=array();

            $maIndex=array_keys($multArray);
            $maSize=count($multArray)-1;

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

               $minElement=$i;
               $tempMin=$multArray[$maIndex[$i]][$sortField];
               $tmpKey=$maIndex[$i];

                for($j=$i+1; $j <= $maSize; $j++)
                  if($multArray[$maIndex[$j]][$sortField] < $tempMin ) {
                     $minElement=$j;
                     $tmpKey=$maIndex[$j];
                     $tempMin=$multArray[$maIndex[$j]][$sortField];

                  }
                  $maIndex[$minElement]=$maIndex[$i];
                  $maIndex[$i]=$tmpKey;
            }

           if($desc)
               for($j=0;$j<=$maSize;$j++)
                  $ResArray[$maIndex[$j]]=$multArray[$maIndex[$j]];
           else
              for($j=$maSize;$j>=0;$j--)
                  $ResArray[$maIndex[$j]]=$multArray[$maIndex[$j]];

           return $ResArray;
       }

// make array
$array['aaa']=array("name"=>"vasia","order"=>1);
$array['bbb']=array("name"=>"petia","order"=>2);
$array['ccc']=array("name"=>"kolia","order"=>3);
$array['ddd']=array("name"=>"zenia","order"=>4);

// set sort 
$SortOrder=0; // desc by default , 1- asc

var_dump(sortByField($array,'order',$SortOrder));

array
  'ddd' => 
    array
      'name' => 'zenia' (length=5)
      'order' => 4
  'aaa' => 
    array
      'name' => 'vasia' (length=5)
      'order' => 1
  'bbb' => 
    array
      'name' => 'petia' (length=5)
      'order' => 2
  'ccc' => 
    array
      'name' => 'kolia' (length=5)
      'order' => 3

?>

danm68 at gmail dot com

6 years ago


sort() used with strings doesn't sort just alphabetically. It sorts all upper-case strings alphabetically first and then sorts lower-case strings alphabetically second. 
Just in case anyone was as confused as I was and I've never seen this mentioned anywhere.

petr dot biza at gmail dot com

6 years ago


Here is a function to sort an array by the key of his sub-array with keep key in top level.



<?php

function sksort(&$array, $subkey="id", $sort_descending=false, $keep_keys_in_sub = false) {

    $temp_array = $array;



    foreach ($temp_array as $key => &$value) {

      

      $sort = array();

      foreach ($value as $index => $val) {

          $sort[$index] = $val[$subkey];

      }

      

      asort($sort);

      

      $keys = array_keys($sort);

      $newValue = array();

      foreach ($keys as $index) {

        if($keep_keys_in_sub)

            $newValue[$index] = $value[$index];

          else

            $newValue[] = $value[$index];

      }

      

      if($sort_descending)

        $value = array_reverse($newValue, $keep_keys_in_sub);

      else

        $value = $newValue;

    }

    

    $array = $temp_array;

  }

?>

nm at thenoodleman dot com

10 years ago


Faster, more effective function:

array_sort (array, ['asc'/'desc'])

Second parameter specifies whether to order ascending or descending. Default is ascending.

function array_sort($array, $type='asc'){
    $result=array();
    foreach($array as $var => $val){
        $set=false;
        foreach($result as $var2 => $val2){
            if($set==false){
                if($val>$val2 && $type=='desc' || $val<$val2 && $type=='asc'){
                    $temp=array();
                    foreach($result as $var3 => $val3){
                        if($var3==$var2) $set=true;
                        if($set){
                            $temp[$var3]=$val3;
                            unset($result[$var3]);
                        }
                    }
                    $result[$var]=$val;    
                    foreach($temp as $var3 => $val3){
                        $result[$var3]=$val3;
                    }
                }
            }
        }
        if(!$set){
            $result[$var]=$val;
        }
    }
    return $result;
}

Works for ordering by integers or strings, no need to specify which.

Example:

$array=array('a' => 50, 'b' => 25, 'c' => 75);
print_r(array_sort($array));

Returns:
Array
(
[b] => 25
[a] => 50
[c] => 75
)

timc at hlyw dot com

11 years ago


I dig the multi_sort function(s) from above.  But, they don't work for hash arrays.  I added a keys variable to keep track of the key value as the array gets sorted.  Feed back welcome.

<?php
function array_qsort (&$array, $column=0, $order=SORT_ASC, $first=0, $last= -2) 
{ 
  // $array  - the array to be sorted 
  // $column - index (column) on which to sort 
  //          can be a string if using an associative array 
  // $order  - SORT_ASC (default) for ascending or SORT_DESC for descending 
  // $first  - start index (row) for partial array sort 
  // $last  - stop  index (row) for partial array sort 
  // $keys  - array of key values for hash array sort
  
  $keys = array_keys($array);
  if($last == -2) $last = count($array) - 1; 
  if($last > $first) { 
   $alpha = $first; 
   $omega = $last;
   $key_alpha = $keys[$alpha]; 
   $key_omega = $keys[$omega];
   $guess = $array[$key_alpha][$column]; 
   while($omega >= $alpha) { 
     if($order == SORT_ASC) { 
       while($array[$key_alpha][$column] < $guess) {$alpha++; $key_alpha = $keys[$alpha]; }
       while($array[$key_omega][$column] > $guess) {$omega--; $key_omega = $keys[$omega]; }
     } else { 
       while($array[$key_alpha][$column] > $guess) {$alpha++; $key_alpha = $keys[$alpha]; }
       while($array[$key_omega][$column] < $guess) {$omega--; $key_omega = $keys[$omega]; }
     } 
     if($alpha > $omega) break; 
     $temporary = $array[$key_alpha]; 
     $array[$key_alpha] = $array[$key_omega]; $alpha++;
     $key_alpha = $keys[$alpha];
     $array[$key_omega] = $temporary; $omega--;
     $key_omega = $keys[$omega];
   } 
   array_qsort ($array, $column, $order, $first, $omega); 
   array_qsort ($array, $column, $order, $alpha, $last); 
  } 
} 
?>

ajanata at gmail dot com

4 years ago


This took me longer than it should have to figure out, but if you want the behavior of sort($array, SORT_STRING) (that is, re-indexing the array unlike natcasesort) in a case-insensitive manner, it is a simple matter of doing usort($array, strcasecmp).

alex dot hristov dot 88 at gmail dot com

4 years ago


As some people have mentioned before sorting a multidimentional array can be a bit tricky. it took me quite a while to get it going but it works as a charm:

<?php
//$order has to be either asc or desc
 function sortmulti ($array, $index, $order, $natsort=FALSE, $case_sensitive=FALSE) {
        if(is_array($array) && count($array)>0) {
            foreach(array_keys($array) as $key) 
            $temp[$key]=$array[$key][$index];
            if(!$natsort) {
                if ($order=='asc')
                    asort($temp);
                else    
                    arsort($temp);
            }
            else 
            {
                if ($case_sensitive===true)
                    natsort($temp);
                else
                    natcasesort($temp);
            if($order!='asc') 
                $temp=array_reverse($temp,TRUE);
            }
            foreach(array_keys($temp) as $key) 
                if (is_numeric($key))
                    $sorted[]=$array[$key];
                else    
                    $sorted[$key]=$array[$key];
            return $sorted;
        }
    return $sorted;
}
?>

cmarshall at gmx dot de

4 years ago


I read up on various problems re: sort() and German Umlaut chars and my head was soon spinning - bug in sort() or not, solution via locale or not, etc. ... (a total newbie here).

The obvious solution for me was quick and dirty: transform the Umlaut chars (present as HTML codes in my case) to their normal equivalent ('ä' = 'ae', 'ö' = 'oe', 'ü' = 'ue', 'ß' = 'ss' etc.), sort the array, then transform back. However there are cases in which a 'Mueller' is really that and does NOT need to be transformed into 'Müller' afterwards. Hence I for example replace the Umlaut itself with it's normal equivalent plus a char not used in the string otherwise (e.g. '_') so that the transfer back to Umlaut would only take place on certain combinations.

Of course any other char instead of '_' can be used as additional char (influencing the sort result). I know that my solution is rough at the edges and may cause other sort problems but it was sufficient for my purpose.

The array '$dat' in this example was filled with German town names (I actually worked with a multiple array ('$dat[][]') but stripped the code down to this as it's easier to understand):

<?php
// START Pre-sorting (Umlaut -> normal letters)
$max = count($dat);
for($totcnt = 0; $totcnt < $max; $totcnt++){
   $dat[$totcnt]=str_replace('&szlig;','ss_',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('&Auml;','Ae_',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('&auml;','ae_',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('&Ouml;','Oe_',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('&ouml;','oe_',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('&Uuml;','Ue_',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('&uuml;','ue_',$dat[$totcnt]);
}
// END Pre-sorting (Umlaut -> normal letters)

// START Sorting //
function compare_towns($a, $b)
{
return strnatcmp($a, $b);
}
usort($dat, 'compare_towns');
// END Sorting //

// START Post-sorting (normal letters -> Umlaut)
for($totcnt = 0; $totcnt < $max; $totcnt++){
   $dat[$totcnt]=str_replace('ss_','&szlig;',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('Ae_','&Auml;',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('ae_','&auml;',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('Oe_','&Ouml;',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('oe_','&ouml;',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('Ue_','&Uuml;',$dat[$totcnt]);
   $dat[$totcnt]=str_replace('ue_','&uuml;',$dat[$totcnt]);
}
// END Post-sorting (normal letters -> Umlaut)
?>

anaz114119 at gmail dot com

5 years ago


sort from textfile by coloumn

example name||date||time||comments

if you want to sort by date

$column = 2

<?php

function array_sort($array,$column){

 $column = $column-1;

 foreach($array as $line){

 $bits = explode("||",$line);

 $bits ="$bits[$column]**$line";

 $array1[]=$bits;

}

 asort($array1);

 foreach($array1 as $line){

 $bit = explode("**",$line);

 $bit ="$bit[1]";

 $array2[]=$bit;

}

 return$array2;

}

?>

poulou_0 at hotmail dot com

5 years ago


if you are not interested in high or low case sort

<?php
//where
$sortable_array[$k] = $v2; 
//put
$sortable_array[$k] = strtolower($v2);

//and where
$sortable_array[$k] = $v;
//put
$sortable_array[$k] = strtolower($v);
?>

sinan at sinaneldem dot com

8 years ago


here is little script which will merge arrays, remove duplicates and sort it by alphabetical order:

<?php

$array1 = array('apple', 'banana','pear');
$array2 = array('grape', 'pear','orange');

function array_unique_merge_sort($array1, $array2){
$array = array_unique(array_merge($array1, $array2));
sort($array);
foreach ($array as $key => $value) {
    $new[$key] = $value;
}
return $new;
}

print_r (array_unique_merge_sort($array1, $array2));

?>

this will print out:

Array ( [0] => apple [1] => banana [2] => grape [3] => orange [4] => pear )

g8z at yahoo dot com

9 years ago


<?php
/**
This sort function allows you to sort an associative array while "sticking" some fields.

$sticky_fields = an array of fields that should not be re-sorted. This is a method of achieving sub-sorts within contiguous groups of records that have common data in some fields.

For example:

$a = array();

$a []= array(
    'name'         => 'Sam',
    'age'         => 23,
    'hire_date'    => '2004-01-01'
);
$a []= array(
    'name'        => 'Sam',
    'age'        => 44,
    'hire_date'    => '2003-03-23'
);
$a []= array(
    'name'        => 'Jenny',
    'age'        => 20,
    'hire_date' => '2000-12-31'
);
$a []= array(
    'name'        => 'Samantha',
    'age'        => 50,
    'hire_date' => '2000-12-14'
);

$sticky_fields = array( 'name' );
print_r( stickysort( $a, 'age', DESC_NUM, $sticky_fields ) );

OUTPUT:

Array
(
    [0] => Array
        (
            [name] => Sam
            [age] => 44
            [hire_date] => 2003-03-23
        )
    [1] => Array
        (
            [name] => Sam
            [age] => 23
            [hire_date] => 2004-01-01
        )
    [2] => Array
        (
            [name] => Jenny
            [age] => 20
            [hire_date] => 2000-12-31
        )
    [3] => Array
        (
            [name] => Samantha
            [age] => 50
            [hire_date] => 2000-12-14
        )
)

Here's why this is the correct output - the "name" field is sticky, so it cannot change its sort order. Thus, the "age" field is only sorted as a sub-sort within records where "name" is identical. Thus, the "Sam" records are reversed, because 44 > 23, but Samantha remains at the bottom, even though her age is 50. This is a way of achieving "sub-sorts" and "sub-sub-sorts" (and so on) within records of identical data for specific fields.

Courtesy of the $5 Script Archive: http://www.tufat.com
**/

define( 'ASC_AZ', 1000 );
define( 'DESC_AZ', 1001 );
define( 'ASC_NUM', 1002 );
define( 'DESC_NUM', 1003 );

function stickysort( $arr, $field, $sort_type, $sticky_fields = array() ) {
    $i = 0;
    foreach ($arr as $value) {
        $is_contiguous = true;
        if(!empty($grouped_arr)) {
            $last_value = end($grouped_arr[$i]);

            if(!($sticky_fields == array())) {
                foreach ($sticky_fields as $sticky_field) {
                    if ($value[$sticky_field] <> $last_value[$sticky_field]) {
                        $is_contiguous = false;
                        break;
                    }
                }
            }
        }
        if ($is_contiguous)
            $grouped_arr[$i][] = $value;
        else
            $grouped_arr[++$i][] = $value;
    }
    $code = '';
    switch($sort_type) {
        case ASC_AZ:
            $code .= 'return strcasecmp($a["'.$field.'"], $b["'.$field.'"]);';
            break;
        case DESC_AZ:
            $code .= 'return (-1*strcasecmp($a["'.$field.'"], $b["'.$field.'"]));';
            break;
        case ASC_NUM:
            $code .= 'return ($a["'.$field.'"] - $b["'.$field.'"]);';
            break;
        case DESC_NUM:
            $code .= 'return ($b["'.$field.'"] - $a["'.$field.'"]);';
            break;
    }

    $compare = create_function('$a, $b', $code);

    foreach($grouped_arr as $grouped_arr_key=>$grouped_arr_value)
        usort ( $grouped_arr[$grouped_arr_key], $compare );

    $arr = array();
    foreach($grouped_arr as $grouped_arr_key=>$grouped_arr_value)
        foreach($grouped_arr[$grouped_arr_key] as $grouped_arr_arr_key=>$grouped_arr_arr_value)
            $arr[] = $grouped_arr[$grouped_arr_key][$grouped_arr_arr_key];

    return $arr;
}
?>

g8z at yahoo dot com

9 years ago


<?php
/**
This sort function allows you to sort an associative array while "sticking" some fields.

$sticky_fields = an array of fields that should not be re-sorted. This is a method of achieving sub-sorts within contiguous groups of records that have common data in some fields.

Courtesy of the $5 Script Archive: http://www.tufat.com
**/

define( 'ASC_AZ', 1000 );
define( 'DESC_AZ', 1001 );
define( 'ASC_NUM', 1002 );
define( 'DESC_NUM', 1003 );

function stickysort( $arr, $field, $sort_type, $sticky_fields = array() ) {
    $i = 0;
    foreach ($arr as $value) {
        $is_contiguous = true;
        if(!empty($grouped_arr)) {
            $last_value = end($grouped_arr[$i]);

            if(!($sticky_fields == array())) {
                foreach ($sticky_fields as $sticky_field) {
                    if ($value[$sticky_field] <> $last_value[$sticky_field]) {
                        $is_contiguous = false;
                        break;
                    }
                }
            }
        }
        if ($is_contiguous)
            $grouped_arr[$i][] = $value;
        else
            $grouped_arr[++$i][] = $value;
    }
    $code = '';
    switch($sort_type) {
        case ASC_AZ:
            $code .= 'return strcasecmp($a["'.$field.'"], $b["'.$field.'"]);';
            break;
        case DESC_AZ:
            $code .= 'return (-1*strcasecmp($a["'.$field.'"], $b["'.$field.'"]));';
            break;
        case ASC_NUM:
            $code .= 'return ($a["'.$field.'"] - $b["'.$field.'"]);';
            break;
        case DESC_NUM:
            $code .= 'return ($b["'.$field.'"] - $a["'.$field.'"]);';
            break;
    }

    $compare = create_function('$a, $b', $code);

    foreach($grouped_arr as $grouped_arr_key=>$grouped_arr_value)
        usort ( $grouped_arr[$grouped_arr_key], $compare );

    $arr = array();
    foreach($grouped_arr as $grouped_arr_key=>$grouped_arr_value)
        foreach($grouped_arr[$grouped_arr_key] as $grouped_arr_arr_key=>$grouped_arr_arr_value)
            $arr[] = $grouped_arr[$grouped_arr_key][$grouped_arr_arr_key];

    return $arr;
}
?>

Emiliyan at ServicesBG dot Com

10 years ago


#This is a function that will sort an array...
function sort_by($array,  $keyname = null, $sortby) {
   $myarray = $inarray = array();    
   # First store the keyvalues in a seperate array
    foreach ($array as $i => $befree) { 
        $myarray[$i] = $array[$i][$keyname];
    }
   # Sort the new array by
    switch ($sortby) {
    case 'asc':
    # Sort an array and maintain index association...
    asort($myarray); 
    break;
    case 'arsort':
    # Sort an array in reverse order and maintain index association 
    arsort($myarray); 
    break;
    case 'natcasesor':
    # Sort an array using a case insensitive "natural order" algorithm
    natcasesort($myarray); 
    break;
    }
    # Rebuild the old array
    foreach ( $myarray as $key=> $befree) {
       $inarray[$key] = $array[$key];
    }
    return $inarray;
} 
sort_by(); example...
$info = sort_by($myarray, 'name', $use = 'asc');    
print_r($info);

arjan321 at hotmail dot com

13 years ago


Ik you want to sort case insensitive, use the natcasesort()

peek at mailandnews dot com

15 years ago


I ran into the same problem with case insensitive sorting. Actually I think there should be a SORT_STRING_CASE flag but I tried the following:



usort($listing, 'strcasecmp');



This didn't work (why not?), but you can do a proper case insensitive sort like this:



usort($listing, create_function('$a,$b','return strcasecmp($a,$b);'));

holdoffhunger at gmail dot com

4 years ago


I have discovered an interesting trick with the sort function.  Many coders are using it to sort options for a user, because a computer will only need sorted data in limited cases.  However, every coder wants their sorted data to be usable.  It's very common to find any sorted data online, and to find options, "Sort by Date," "Sort Alphabetically," etc., etc., whether you're looking at an online catalogue or some bulletin board.

The trick is to use a combination of html commenting and str_pad's to do definitive "sort by" functions.  Let me demonstrate with an example: consider two arrays, Sorted_By_Date and Sorted_By_Name.  You want every element to be "<option value=something>Option Name</option", so that you can do a simple foreach statement that prints every option value.  But, sorting these arrays will technically sort just sort whatever you put into "value".  So, here's a neat trick.  Make every entry "<!-- Sort_Value --><option value=something>Option Name</option."  That way, when you sort, it'll have to sort technically by whatever is the Sort_Value.

The greatness of this trick is that you can make as many "sort this data by X" fields as you want!  Just create multiple arrays, each with the same option values and names, but with a different value put in "Sort_Value", which could be a date, a name, a price, etc..  With numbers, you may need to use the str_pad function, to push all of the zeros out to the left, for a proper sort.  For instance, in my code, that looks like...

<?php

                $number_of_versions_sort_value = str_pad($number_of_versions, 20, "0", STR_PAD_LEFT);

?>

markrose at markrose dot ca

4 years ago


I've yet to come across a fast way to merge sorted arrays by a user value. Merging the arrays and using PHP's usort isn't efficient, as it doesn't take advantage of the existing sorting. So I wrote my own merge sorted arrays by user value function. The limit parameter can be used be used to limit the number of results (there is no point sorting more results than needed). This sort is stable: values will be taken preferentially from the first, then second, etc., array inside $merge_arrays.



Note that this function will fail if a user value is boolean false. It could be adapted to hold the best value inside an array at some performance penalty. It could also be adapted to comparing strings case-insensitively.



To give you some idea of the performance, my machine will sort out the first 1000 values of 10 sorted arrays of 1000 values each in under 40 ms, using an integer sort field. Not fast by C standards, but a vast improvement over usort'ing 10,000 values.



<?php

function merge_sorted_arrays_by_field ($merge_arrays, $sort_field, $sort_desc = false, $limit = 0)

{

    $array_count = count($merge_arrays);

    

    // fast special cases...

    switch ($array_count)

    {

        case 0: return array();

        case 1: return $limit ? array_slice(reset($merge_arrays), 0, $limit) : reset($merge_arrays);

    }

    

    if ($limit === 0)

        $limit = PHP_INT_MAX;

    

    // rekey merge_arrays array 0->N

    $merge_arrays = array_values($merge_arrays);



    $best_array = false;

    $best_value = false;

    

    $results = array();

    

    // move sort order logic outside the inner loop to speed things up

    if ($sort_desc)

    {

        for ($i = 0; $i < $limit; ++$i)

        {

            for ($j = 0; $j < $array_count; ++$j)

            {

                // if the array $merge_arrays[$j] is empty, skip to next

                if (false === ($current_value = current($merge_arrays[$j])))

                    continue;

                

                // if we don't have a value for this round, or if the current value is bigger...

                if ($best_value === false || $current_value[$sort_field] > $best_value[$sort_field])

                {

                    $best_array = $j;

                    $best_value = $current_value;

                }

            }

            

            // all arrays empty?

            if ($best_value === false)

                break;

            

            $results[] = $best_value;

            $best_value = false;

            next($merge_arrays[$best_array]);

        }

    }

    else

    {

        for ($i = 0; $i < $limit; ++$i)

        {

            for ($j = 0; $j < $array_count; ++$j)

            {

                if (false === ($current_value = current($merge_arrays[$j])))

                    continue;

                

                // if we don't have a value for this round, or if the current value is smaller...

                if ($best_value === false || $current_value[$sort_field] < $best_value[$sort_field])

                {

                    $best_array = $j;

                    $best_value = $current_value;

                }

            }

            

            // all arrays empty?

            if ($best_value === false)

                break;

            

            $results[] = $best_value;

            $best_value = false;

            next($merge_arrays[$best_array]);

        }

    }

    

    return $results;

}

?>

Dollar Hauler Admin

6 years ago


I could never find a way to sort multidimensional arrays with 5+ keys while maintaining the data structure, but here it is:

(you can add an infinite number of keys, but it has to be added manually :\ )

<?php

$array[0]['name']  = 'Chris';
$array[0]['phone'] = '3971095';
$array[0]['year']  = '1978';
$array[0]['address'] = 'Street 1';

$array[1]['name']  = 'Breanne';
$array[1]['phone'] = '3766350';
$array[1]['year']  = '1990';
$array[1]['address'] = 'Street 2';

$array[2]['name']  = 'Dusty';
$array[2]['phone'] = '1541120';
$array[2]['year']  = '1982';
$array[2]['address'] = 'Street 3';

function multisort($array, $sort_by, $key1, $key2=NULL, $key3=NULL, $key4=NULL, $key5=NULL, $key6=NULL){
    // sort by ?
    foreach ($array as $pos =>  $val)
        $tmp_array[$pos] = $val[$sort_by];
    asort($tmp_array);
    
    // display however you want
    foreach ($tmp_array as $pos =>  $val){
        $return_array[$pos][$sort_by] = $array[$pos][$sort_by];
        $return_array[$pos][$key1] = $array[$pos][$key1];
        if (isset($key2)){
            $return_array[$pos][$key2] = $array[$pos][$key2];
            }
        if (isset($key3)){
            $return_array[$pos][$key3] = $array[$pos][$key3];
            }
        if (isset($key4)){
            $return_array[$pos][$key4] = $array[$pos][$key4];
            }
        if (isset($key5)){
            $return_array[$pos][$key5] = $array[$pos][$key5];
            }
        if (isset($key6)){
            $return_array[$pos][$key6] = $array[$pos][$key6];
            }
        }
    return $return_array;
    }

//usage (only enter the keys you want sorted):

$sorted = multisort($array,'year','name','phone','address');
print_r($sorted);

//output:
Array ( [0] => Array ( [year] => 1978 [name] => Chris [phone] => 3971095 [address] => Street 1 ) [2] => Array ( [year] => 1982 [name] => Dusty [phone] => 1541120 [address] => Street 3 ) [1] => Array ( [year] => 1990 [name] => Breanne [phone] => 3766350 [address] => Street 2 ) )

phpnet at theindy dot net

6 years ago


In response to the msort function I find that the array_multisort function is a lot faster.

-John

james at miicro dot net

10 years ago


Further to john dot dutcher at highmark dot com's comments - padding the name could cause a problem if you get abnormally long names, it might be better to rebuild the array thus:

Array (
[0] => Array ( [sortname_01] => Dutcher [sortname_02] => F [sortname_03] => John [name] => Dutcher, John F )
[1] => Array ( [sortname_01] => Dutch [sortname_02] => A [sortname_03] => Roger [name] => Dutch, Roger A )
[2] => Array ( [sortname_01] => Dut [sortname_02] => H [sortname_03] => Maurice [name] => Dut, Maurice H )
[3] => Array ( [sortname_01] => Dut [sortname_02] => S [sortname_03] => Mildred [name] => Dut, Mildred S )
)

which should give:

Array (
[0] => Array ( [sortname_01] => Dut [sortname_02] => H [sortname_03] => Maurice [name] => Dut, Maurice H )
[1] => Array ( [sortname_01] => Dut [sortname_02] => S [sortname_03] => Mildred [name] => Dut, Mildred S )
[2] => Array ( [sortname_01] => Dutch [sortname_02] => A [sortname_03] => Roger [name] => Dutch, Roger A )
[3] => Array ( [sortname_01] => Dutcher [sortname_02] => F [sortname_03] => John [name] => Dutcher, John F )
)

jalil at measat dot org

7 years ago


this is an implementation of the complement of 

Matthew Hood's objectSort (http://my.php.net/manual/en/function.sort.php#75036), which i found very convenient for sorting objects.



this does the reverse, it sorts according to the key

selected for the object but in reverse order.

and having both sort methods allows consistency and convenience for sorting objects, if speed isn't your major concern. 



the only change ( apart form data being reworded as object )  is the use of < instead of > in the original.

you could of couse incorporate all in one routine, but why

complicate matters.



<?php

    function objectRSort(&$object, $key)

    {

        for ($i = count($object) - 1; $i >= 0; $i--)

        {

          $swapped = false;

          for ($j = 0; $j < $i; $j++)

          {

               if ($object[$j]->$key < $object[$j + 1]->$key)

               {

                    $tmp = $object[$j];

                    $object[$j] = $object[$j + 1];       

                    $object[$j + 1] = $tmp;

                    $swapped = true;

               }

          }

          if (!$swapped) return;

        }

    }

?>

www at designdetector dot com

7 years ago


To sort an array of multiple text fields alphabetically you have to make the text lowercase before sorting the array. Otherwise PHP puts acronyms before words. You can see this in my example code. Simply store the original text field at the end of the array line and call it later from there. You can safely ignore the lowercase version which is added to the start of the array line.

<?php
echo '<pre>ORIGINAL DATA:
<br />';

$data = array(
'Saturn|7|8|9|0||',
'Hello|0|1|2|3||',
'SFX|5|3|2|4||',
'HP|9|0|5|6||'
);

print_r($data);

sort($data);
reset($data);

echo '<br />RAW SORT:
<br />';

print_r($data);

for ($c = 0; $c < count($data); $c++) {
    list ($letter,$g1,$g2,$g3,$g4,$end) = explode ('|', $data[$c]);
    $lowercase = strtolower($letter);
    $data2[$c] = array($lowercase,$g1,$g2,$g3,$g4,$letter);
}

sort($data2);
reset($data2);

echo '<br />LOWERCASE SORT:
<br />';

print_r($data2);

echo '</pre>';
?>

NBS Studio

8 years ago


This is my way of sorting files into date modified date order. It worked for me!

$dir='topics';
$ext='php5';
$files=scandir($dir);
foreach($files as $fs){
    if(($fs!='.')&&($fs!='..')){
        $fs1.='¬'.filemtime($dir.'/'.$fs).'#'.$fs;
    }
}
$fs2=split('[¬]',$fs1);
arsort($fs2);
foreach($fs2 as $fs3){
    if(eregi($ext,$fs3)){
        $fs4.='¬'.$fs3;
    }
}
$fs5=split('[#]',$fs4);
foreach($fs5 as $fs6){
    if(eregi($ext,$fs6)){
        $fs7.='¬'.$fs6;
    }
}
$fs8=split('[¬]',$fs7);
foreach($fs8 as $fs9){
    $file_list.=$fs9.'
</br>';
}

print $file_list;

jesper at snt dot utwente dot nl

10 years ago


If you sort an array of objects, the first variable in the object will be used for sorting:

<?php
class foo
{
  var $value; //First variable: Used for sorting
  var $id;

  function foo($i, $v)
  {
     $this->id = $i;
     $this->value = $v;
  }

}

for ($i = 0; $i < 10; $i++)
{
  $bar[] = new foo($i,rand(1,10));
}

// This will sort on value
sort($bar);
print_r($bar);
?>

Compare the piece of code above with the following:

<?php
class foo
{
  var $id; //First variable: Used for sorting
  var $value;

  function foo($i, $v)
  {
     $this->id = $i;
     $this->value = $v;
  }

}

for ($i = 0; $i = 10; $i++)
{
  $bar[] = new foo($i,rand(1,10));
}

// This will sort on id
sort($bar);
print_r($bar);
?>

As you can see the location of declaration of the variables matter!
If you want to sort on both or on a combination of variables, use ksort()

anthony at ectrolinux dot com

11 years ago


In a brief addition to the previous poster's message, the ascending sorting order used by PHP directly corresponds to ISO-8859-1 (ASCII). Therefore the character \48 (numeral 0) would be placed before the character \82 (R), which would be placed before the character \110 (n), and so forth.

raul at jimi dot com dot mx

10 years ago


I had an array like this:
$arr=array (1,4,3,6,5);

which returns this:
$arr[0]=1
$arr[1]=4
$arr[2]=3
$arr[3]=6
$arr[4]=5

But lets say i remove [2] which is number 3, i get:

$arr[0]=1
$arr[1]=4
$arr[3]=6
$arr[4]=5

And i want to reindex without doing a sort because i dont want to lose the order of the numbers (like a pop in a stack but in the middle of the list), i do this:

$arr=array_chunk($arr,count($arr));
$arr=$arr[0];

the result is:

$arr[0]=1
$arr[1]=4
$arr[2]=6
$arr[3]=5

This can be applied mostly for tree sorting, when you only have the id and the parent values of the node, and you want to have N levels.

totszwai at gail dot com

3 months ago


For those who wanna go with simple approach without hammering your head too much... This does the job, granted might not be efficient, but is really short. :P

Let $all be a key/value paired array...

$keys = array_keys($all);
sort($keys);
$sorted = array();
foreach($keys as $k) {
       $sorted[$k] = $all[$k];
}
$all = $sorted;
unset($sorted);

alishahnovin at hotmail dot com

8 years ago


I had a multidimensional array, which needed to be sorted by one of the keys. This is what I came up with...

<?php
function msort($array, $id="id") {
        $temp_array = array();
        while(count($array)>0) {
            $lowest_id = 0;
            $index=0;
            foreach ($array as $item) {
                if ($item[$id]<$array[$lowest_id][$id]) {
                    $lowest_id = $index;
                }
                $index++;
            }
            $temp_array[] = $array[$lowest_id];
            $array = array_merge(array_slice($array, 0,$lowest_id), array_slice($array, $lowest_id+1));
        }
        return $temp_array;
    }
?>

Ex:

<?php

//oh no, this is not in the ordered by id!!
$data[] = array("item"=>"item 4", "id"=>4);
$data[] = array("item"=>"item 1", "id"=>1);
$data[] = array("item"=>"item 3", "id"=>3);
$data[] = array("item"=>"item 2", "id"=>2);

var_dump(  msort($data)  ); //just msort it!

/* outputs 

array
  0 => 
    array
      'item' => 'item 1' (length=6)
      'id' => 1
  1 => 
    array
      'item' => 'item 2' (length=6)
      'id' => 2
  2 => 
    array
      'item' => 'item 3' (length=6)
      'id' => 3
  3 => 
    array
      'item' => 'item 4' (length=6)
      'id' => 4

*/

?>

jerome a-t+ yamafoto d*o*t com

10 years ago


when sorting an array, beware of variable type from elements you put in this array

Example:

$a = 2; // $a is an integer
$b = 'item';
$arr = array($a, $b);
sort($arr);

print_r($arr);

this will output:
$arr[0] = 'item';
$arr[1] = 2;

$a = '2'; // $a is a string
$b = 'item';
$arr = array($a, $b);
sort($arr);

print_r($arr);

this will output:
$arr[0] = '2';
$arr[1] = 'item'

to avoid this problem use:

sort($arr, SORT_STRING)

teunkloosterman at hotmail dot com

11 years ago


Just to show how it sorts:

<?php
$array = Array("1", "2", "3", "4", "5", "6", "7", "8", "9", "0", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", " ", "!", "@", "#", "\\\$", "%", "^", "&", "*", "(", ")", "_", "-", "=", "+", "\\\\", "|", ",", "<", ".", ">", "?", "'", "\\\"", "`", "~");
sort($array);
echo implode("", $array);
?>

returns:

 !"#$%&'()*+,-.0123456789<=>?
@ABCDEFGHIJKLMNOPQRSTUVWXYZ
\^_`abcdefghijklmnopqrstuvwxyz|~

note: the result begins with a space

Anonymous

6 years ago


[EDIT BY danbrown AT php DOT net: The code provided by this anonymous author contains bugfixes for and additions to code originally donated by "toenie" on 07-NOV-09.  The original author included the following note: "If you want to sort while using an 2 dimensional array, you can use this script I just wrote for myself. I thought it could be helpful for other people too."]



I also added the ability to sort in ascending and descending order.



$order = "ASC" will sort the array in ascending order

$order = "DESC" will sort the array in descending order



Here is the code:



<?php

    function order_array_num ($array, $key, $order = "ASC") 

    {

        $tmp = array();

        foreach($array as $akey => $array2) 

        {

            $tmp[$akey] = $array2[$key];

        }

        

        if($order == "DESC")

        {arsort($tmp , SORT_NUMERIC );}

        else

        {asort($tmp , SORT_NUMERIC );}



        $tmp2 = array();        

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

        {

            $tmp2[$key] = $array[$key];

        }        

        

        return $tmp2;

    }

?>

ludvig dot ericson at gmail dot com

10 years ago


A tip for those who like "raul at jimi dot com dot mx" need to preserve keys after changing stuff in the middle of an array:
array_values.

Example:
<?php
$array = array(1, 2, 5, 9, 3);
unset($array[3]); // Remove index 3, which is 9.
$array = array_values($array);
?>

Hint: array_values can be fine for removing keys and reindex them by number instead, too (applies to functions like posix_pwgetuid which returns an associative array, unlike C and others, call array_values on it, and it'll be the same format IIRC.)

phpdotnetNO_SPAM at electronic-strategy dot com

14 years ago


/*

Small function to Alphabetically sort Multidimensional arrays by index values of an n dimension array. 



I have only tested this for sorting an array of up to 6 dimensions by a value within the second dimension. This code is very rough and works for my purposes, but has not been tested beyond my needs.



Although a little clunky and not a mathematical type algorithm, it get's the job done. It theoretically overcomes many of the problems I have seen with multidimensional arrays in that it is possible to specify within the function, not by reference :-(, which index you wish to sort by, no matter how many dimensions down.



call function by assigning it to a new / existing array:



$row_array = multidimsort($row_array);

*/



function multidimsort($array_in) {

     $multiarray = array();

    $array_out = array();

    $loopvalue = 0;

    

    /* -1 as traversal of array starts from 0, count() starts from 1 */

    $multicount = count($array_in) - 1; 



    /* add the indexes you wish to sort array by to a new array in this case index is two levels down, but shouldn't make a difference if it goes further indexes down. (Not tested!) */

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

        array_push($multiarray, $array_in[$i][2]);

        //array_push($multiarray, $array_in[$i][2][4]);

        //array_push($multiarray, $array_in[$i][1][3][7]);

    }

    

    /* alphabetically sort the new array (Ascending in this case) can chage sort to whatever type you like. Even apply user-defined sort. */

    asort($multiarray);

    

    /* reset internal pointer to beginning of array after above sort */

    reset($multiarray);

    

    /* traverse new array of index values and add the corresponding element of the input array to the correct position in the output array */

    while (list ($key, $val) = each ($multiarray)) {

        

        $array_out[$loopvalue] = $array_in[$key];

        

        $loopvalue++;

    }



    /* return the output array which is all nicely sorted by the index you wanted! */

    return $array_out;

}

sort

Description

Parameters

Return Values

Changelog

Examples

Notes

See Also

User Contributed Notes