a quick reminder on the syntax if you want to use uasort in a Class or Object:
<?php
// procedural:
uasort($collection, 'my_sort_function');
// Object Oriented
uasort($collection, array($this, 'mySortMethod'));
// Objet Oriented with static method
uasort($collection, array('self', 'myStaticSortMethod'));
?>
uasort
(PHP 4, PHP 5, PHP 7)
uasort — Ordena un array con una función de comparación definida por el usuario y mantiene la asociación de índices
Descripción
Esta función ordena un array tal que los índices de array mantienen sus correlaciones con los elementos del array con los que están asociados, usando una función de comparación definida por el usuario.
Se usa pricipalmente cuando se ordenan arrays asociativos donde el orden del elemento mismo es significante.
Nota:
Si dos miembros se comparan como iguales, su orden relativo en el array oredenado será indefinido.
Parámetros
Valores devueltos
Devuelve TRUE en caso de éxito o FALSE en caso de error.
Ejemplos
Ejemplo #1 Ejemplo básico de uasort()
<?php
// Función de comparación
function cmp($a, $b) {
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}
// Array a ser ordenado
$array = array('a' => 4, 'b' => 8, 'c' => -1, 'd' => -9, 'e' => 2, 'f' => 5, 'g' => 3, 'h' => -4);
print_r($array);
// Ordenar e imprimir el array resultante
uasort($array, 'cmp');
print_r($array);
?>
El resultado del ejemplo sería:
Array
(
[a] => 4
[b] => 8
[c] => -1
[d] => -9
[e] => 2
[f] => 5
[g] => 3
[h] => -4
)
Array
(
[d] => -9
[h] => -4
[c] => -1
[e] => 2
[g] => 3
[a] => 4
[f] => 5
[b] => 8
)
Ver también
- usort() - Ordena un array según sus valores usando una función de comparación definida por el usuario
- comparación de funciones de orden de arrays
add a note
User Contributed Notes 16 notes
magikMaker ¶
7 years ago
php at clement dot hk ¶
4 years ago
If you want to keep the order when two members compare as equal, use this.
<?php
function stable_uasort(&$array, $cmp_function) {
if(count($array) < 2) {
return;
}
$halfway = count($array) / 2;
$array1 = array_slice($array, 0, $halfway, TRUE);
$array2 = array_slice($array, $halfway, NULL, TRUE);
stable_uasort($array1, $cmp_function);
stable_uasort($array2, $cmp_function);
if(call_user_func($cmp_function, end($array1), reset($array2)) < 1) {
$array = $array1 + $array2;
return;
}
$array = array();
reset($array1);
reset($array2);
while(current($array1) && current($array2)) {
if(call_user_func($cmp_function, current($array1), current($array2)) < 1) {
$array[key($array1)] = current($array1);
next($array1);
} else {
$array[key($array2)] = current($array2);
next($array2);
}
}
while(current($array1)) {
$array[key($array1)] = current($array1);
next($array1);
}
while(current($array2)) {
$array[key($array2)] = current($array2);
next($array2);
}
return;
}
function cmp($a, $b) {
if($a['n'] == $b['n']) {
return 0;
}
return ($a['n'] > $b['n']) ? -1 : 1;
}
$a = $b = array(
'a' => array("l" => "A", "n" => 1),
'b' => array("l" => "B", "n" => 2),
'c' => array("l" => "C", "n" => 1),
'd' => array("l" => "D", "n" => 2),
'e' => array("l" => "E", "n" => 2),
);
uasort($a, 'cmp');
print_r($a);
stable_uasort($b, 'cmp');
print_r($b);
?>
returns
Array
(
[e] => Array
(
[l] => E
[n] => 2
)
[b] => Array
(
[l] => B
[n] => 2
)
[d] => Array
(
[l] => D
[n] => 2
)
[c] => Array
(
[l] => C
[n] => 1
)
[a] => Array
(
[l] => A
[n] => 1
)
)
Array
(
[b] => Array
(
[l] => B
[n] => 2
)
[d] => Array
(
[l] => D
[n] => 2
)
[e] => Array
(
[l] => E
[n] => 2
)
[a] => Array
(
[l] => A
[n] => 1
)
[c] => Array
(
[l] => C
[n] => 1
)
)
https://bugs.php.net/bug.php?id=53341
php at eden2 dot com ¶
15 years ago
Is it just me, or are the examples below misleading, and actually demonstrating situations that would be more appropriate for usort()?
After trying to make sense of the uasort() description, it sounds like it's more for sorting a 1D array like this:
"john" => "$23.12"
"tim" => "$6.50"
"bob" => "$18.54"
and getting back:
"tim" => "$6.50"
"bob" => "$18.54"
"john" => $23.12"
(assuming, of course, that your sort function is lopping off the $ and evaluating as a number -- which would complicate the use of asort() ;)
yannick dot battail at gmail dot com ¶
7 years ago
An Example using anonymous function.
Anonymous functions make some time the code easier to understand.
<?php
$fruits = array('Orange9','Orange11','Orange10','Orange6','Orange15');
uasort ( $fruits , function ($a, $b) {
return strnatcmp($a,$b); // or other function/code
}
);
print_r($fruits);
?>
returns
Array
(
[3] => Orange6
[0] => Orange9
[2] => Orange10
[1] => Orange11
[4] => Orange15
)
php arobase kochira period com ¶
10 years ago
Difference between uasort() and usort(), the missing example ...
<?php
$arr = array ( 10 => array('id' => 'dix', 'aa' => '1010'),
100 => array('id' => 'cent', 'aa' => '100100'),
2 => array('id' => 'deux', 'aa' => '22'),
7 => array('id' => 'sept', 'aa' => '77'));
// id sorting
function so ($a, $b) { return (strcmp ($a['id'],$b['id'])); }
?>
*** uasort($arr, 'so') output:
<?php Array (
[100] => Array
(
[id] => cent
[aa] => 100100
)
[2] => Array
(
[id] => deux
[aa] => 22
)
[10] => Array
(
[id] => dix
[aa] => 1010
)
[7] => Array
(
[id] => sept
[aa] => 77
))?>
*** usort($arr, 'so') output:
<?php Array (
[0] => Array
(
[id] => cent
[aa] => 100100
)
[1] => Array
(
[id] => deux
[aa] => 22
)
[2] => Array
(
[id] => dix
[aa] => 1010
)
[3] => Array
(
[id] => sept
[aa] => 77
))?>
alf at prisguide dot no ¶
1 year ago
User "php at clement dot hk" already provided a stable uasort function, but I find this wrapper much shorter and easier to understand:
https://github.com/vanderlee/PHP-stable-sort-functions/blob/master/classes/StableSort.php
function stable_uasort(array &$array, $value_compare_func) {
$index = 0;
foreach ($array as &$item) {
$item = array($index++, $item);
}
$result = uasort($array, function($a, $b) use($value_compare_func) {
$result = call_user_func($value_compare_func, $a[1], $b[1]);
return $result == 0 ? $a[0] - $b[0] : $result;
});
foreach ($array as &$item) {
$item = $item[1];
}
return $result;
}
stilgar_cpsNOSPAM at zipmail dot NOSPAMcom dot br ¶
16 years ago
Use example:
$array[0]['Fator1']=7;
$array[0]['Fator2']="Name";
$array[1]['Fator1']=5;
$array[1]['Fator2']="Name";
$array[2]['Fator1']=7;
$array[2]['Fator2']="NameDiferente";
.....
We want to order by Fator1, then Fator2, then:
function Compare($ar1, $ar2)
{
if ($ar1['Fator1']<$ar2['Fator1'])
return -1;
else if ($ar1['Fator1']>$ar2['Fator1'])
return 1;
if ($ar1['Fator2']<$ar2['Fator2'])
return -1;
else if ($ar1['Fator2']>$ar2['Fator2'])
return 1;
return 0;
}
To sort now, we use:
uasort($array, 'Compare');
iborodikhin at gmail dot com ¶
5 years ago
To shuffle assoc array preserving keys just do this:
<?php uasort(
$array,
function ($a, $b) {
return mt_rand(0, 1) > 0 ? 1 : -1;
}
); ?>
phire_sk ¶
7 years ago
I tried using some of the previous built multisorts, but they weren't working as expected.
So, I made my own Class, and it seems to work wonderfully.
Here is the code:
<?php
/************************************
* Allows sorting multi-dimensional
* arrays by a specific key and in
* asc or desc order
**/
class multiSort
{
var $key; //key in your array
//runs the sort, and returns sorted array
function run ($myarray, $key_to_sort, $type_of_sort = '')
{
$this->key = $key_to_sort;
if ($type_of_sort == 'desc')
uasort($myarray, array($this, 'myreverse_compare'));
else
uasort($myarray, array($this, 'mycompare'));
return $myarray;
}
//for ascending order
function mycompare($x, $y)
{
if ( $x[$this->key] == $y[$this->key] )
return 0;
else if ( $x[$this->key] < $y[$this->key] )
return -1;
else
return 1;
}
//for descending order
function myreverse_compare($x, $y)
{
if ( $x[$this->key] == $y[$this->key] )
return 0;
else if ( $x[$this->key] > $y[$this->key] )
return -1;
else
return 1;
}
}
?>
bpolaszek at gmail dot com ¶
1 month ago
Keep in mind that PHP sorting functions are not reliable to handle "stable sorting", even since PHP7+.
It might work on small arrays, but not on "big" ones (100 items are enough for the stable sorting to fail).
<?php
$a = array_fill(0, 100, 'foo');
$b = $a;
var_dump($b === $a); // bool(true)
uasort($a, function () {
return 0; // Consider all items are the same
});
var_dump($b === $a); // bool(false)
?>
To ensure $b === $a, use a 3rd-party stable sorting function:
http://php.net/manual/en/function.uasort.php#121283
Anonymous ¶
4 years ago
//this fix the problem of if any of these sort functions evaluates two members as equal then the order is undefined (the sorting is not stable).
$pos=0;
foreach($values as $k => $v)
$tosort[$k]=array($v,$pos++);
uasort($tosort,function($a, $b) {
if($a[0] != $b[0])return ($a[0] < $b[0]) ? -1 : 1;
return ($a[1] < $b[1]) ? -1 : 1;}
);
foreach($tosort as $k => $v)
$values[$k]=$v[0];
ayaou dot mohammed at gmail dot com ¶
2 years ago
// Anonumous functions
uasort($collection, array($this, function($a, $b){
//logic
}));
Said Dashuk ¶
6 years ago
My simple and effective solution for sort multi-dimensional array by any key:
<?php
function sort_by_key ($arr,$key) {
global $key2sort;
$key2sort = $key;
uasort($arr, 'sbk');
return ($arr);
}
function sbk ($a, $b) {global $key2sort; return (strcasecmp ($a[$key2sort],$b[$key2sort]));}
?>
paul at webtop-designs dot com ¶
8 years ago
Just expanding on php arobase kochira period com's method:
If you are looking to sort a multi-D array by a specific column and have entries in both upper and lower case, simply drop the entries to lowercase before doing the strcmp.
<?php
$dirs = array(
array('name' => 'First Folder', 'path' => 'sompath'),
array('name' => 'second folder', 'path' => 'sompath2'),
array('name' => 'Third Folder', 'path' => 'sompath3')
);
function so($a, $b) {
return (strcmp (strtolower($a['name']), strtolower($b['name'])));
}
?>
dholmes at jccc d0t net ¶
15 years ago
Here is a little sort function that actually uses a dynamic callback for usort to do it's thing.
It assumes your data is in the form of:
$data = array(
array('ID'=>'6','LAST'=>'Holmes','FIRST'=>'Dan'),
array('ID'=>'1234','LAST'=>'Smith','FIRST'=>'Agent K'),
array('ID'=>'2','LAST'=>'Smith','FIRST'=>'Agent J'),
array('ID'=>'4','LAST'=>'Barney','FIRST'=>'Bob'));
Now, you want to sort on one or more cols, don't you?
masort($data, 'LAST,FIRST');
or
masort($data,array('FIRST','ID'));
Of course you could add a bunch to it (like numeric comparison if appropriate, desc/asc, etc) but it works for me.
function masort(&$data, $sortby){
if(is_array($sortby)){
$sortby = join(',',$sortby);
}
uasort($data,create_function('$a,$b','$skeys = split(\',\',\''.$sortby.'\');
foreach($skeys as $key){
if( ($c = strcasecmp($a[$key],$b[$key])) != 0 ){
return($c);
}
}
return($c); '));
}
Notice that I am splitting the string in the comparison function? While this is certainly slower, it was the only way I would find to "pass" and "array". If anyone has a better way, please suggest. Then inside, we (string) compare the values only moving to the next key if the values are the same...and so on, and so on.
naholyr at yahoo dot fr ¶
15 years ago
You can sort a multidimensionnal array by any of its key with this function:
function multi_sort($array, $key)
{
$cmp_val="((\$a['$key']>\$b['$key'])?1:
((\$a['$key']==\$b['$key'])?0:-1))";
$cmp=create_function('$a, $b', "return $body;");
uasort($array, $cmp);
return $array;
}
example:
$myarray = array(
array("name"=>"kernighan", "language"=>"c"),
array("name"=>"lerdorf", "language"=>"php"),
array("name"=>"Stroustrup", "language"=>"c++"),
array("name"=>"Gosling", "language"=>"java")
);
multi_sort($myarray, "name") returns:
name=Gosling language=java
name=Kernighan language=c
name=Lerdorf language=php
name=Stroustrup language=c++
