array_unique
(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)
array_unique — 移除数组中重复的值
说明
array_unique(array
$array, int $flags = SORT_STRING): array
array_unique() 接受
array 作为输入并返回没有重复值的新数组。
注意键名保留不变。如果在指定了 flags 时存在多个相等的元素，
会保留第一个相等的元素的键（key）和值（value）。
注意: 当且仅当
(string) $elem1 === (string) $elem2时两个单元被认为相同。 例如，字符串表达一样时，会使用首个元素。
参数
-
array -
输入的数组。
-
flags -
第二个可选参数
flags可用于修改排序行为：排序类型标记：
-
SORT_REGULAR- 按照通常方法比较（不修改类型） -
SORT_NUMERIC- 按照数字形式比较 -
SORT_STRING- 按照字符串形式比较 -
SORT_LOCALE_STRING- 根据当前的本地化设置，按照字符串比较。
-
返回值
返回过滤后的数组。
更新日志
| 版本 | 说明 |
|---|---|
| 7.2.0 |
如果 flags 是 SORT_STRING，
之前会复制 array 并移除非唯一数组（之后并不打包数组），
现在是通过添加唯一元素来生成新数组。这可能会导致不同的数字索引。
|
范例
示例 #1 array_unique() 例子
<?php
$input = array("a" => "green", "red", "b" => "green", "blue", "red");
$result = array_unique($input);
print_r($result);
?>
以上例程会输出：
Array
(
[a] => green
[0] => red
[1] => blue
)
示例 #2 array_unique() 和类型
<?php
$input = array(4, "4", "3", 4, 3, "3");
$result = array_unique($input);
var_dump($result);
?>
以上例程会输出：
array(2) {
[0] => int(4)
[2] => string(1) "3"
}
注释
注意: 注意， array_unique() 不能应用于多维数组。
add a note
User Contributed Notes 28 notes
Ghanshyam Katriya(anshkatriya at gmail) ¶
7 years ago
Create multidimensional array unique for any single key index.
e.g I want to create multi dimentional unique array for specific code
Code :
My array is like this,
<?php
$details = array(
0 => array("id"=>"1", "name"=>"Mike", "num"=>"9876543210"),
1 => array("id"=>"2", "name"=>"Carissa", "num"=>"08548596258"),
2 => array("id"=>"1", "name"=>"Mathew", "num"=>"784581254"),
);
?>
You can make it unique for any field like id, name or num.
I have develop this function for same :
<?php
function unique_multidim_array($array, $key) {
$temp_array = array();
$i = 0;
$key_array = array();
foreach($array as $val) {
if (!in_array($val[$key], $key_array)) {
$key_array[$i] = $val[$key];
$temp_array[$i] = $val;
}
$i++;
}
return $temp_array;
}
?>
Now, call this function anywhere from your code,
something like this,
<?php
$details = unique_multidim_array($details,'id');
?>
Output will be like this :
<?php
$details = array(
0 => array("id"=>"1","name"=>"Mike","num"=>"9876543210"),
1 => array("id"=>"2","name"=>"Carissa","num"=>"08548596258"),
);
?>
falundir at gmail dot com ¶
4 years ago
I find it odd that there is no version of this function which allows you to use a comparator callable in order to determine items equality (like array_udiff and array_uintersect). So, here's my version for you:
<?php
function array_uunique(array $array, callable $comparator): array {
$unique_array = [];
do {
$element = array_shift($array);
$unique_array[] = $element;
$array = array_udiff(
$array,
[$element],
$comparator
);
} while (count($array) > 0);
return $unique_array;
}
?>
And here is a test code:
<?php
class Foo {
public $a;
public function __construct(int $a) {
$this->a = $a;
}
}
$array_of_objects = [new Foo(2), new Foo(1), new Foo(3), new Foo(2), new Foo(2), new Foo(1)];
$comparator = function (Foo $foo1, Foo $foo2): int {
return $foo1->a <=> $foo2->a;
};
var_dump(array_uunique($array_of_objects, $comparator)); // should output [Foo(2), Foo(1), Foo(3)]
?>
stoff@ ¶
5 years ago
In reply to performance tests array_unique vs foreach.
In PHP7 there were significant changes to Packed and Immutable arrays resulting in the performance difference to drop considerably. Here is the same test on php7.1 here;
http://sandbox.onlinephpfunctions.com/code/2a9e986690ef8505490489581c1c0e70f20d26d1
$max = 770000; //large enough number within memory allocation
$arr = range(1,$max,3);
$arr2 = range(1,$max,2);
$arr = array_merge($arr,$arr2);
$time = -microtime(true);
$res1 = array_unique($arr);
$time += microtime(true);
echo "deduped to ".count($res1)." in ".$time;
// deduped to 513333 in 1.0876770019531
$time = -microtime(true);
$res2 = array();
foreach($arr as $key=>$val) {
$res2[$val] = true;
}
$res2 = array_keys($res2);
$time += microtime(true);
echo "<br />deduped to ".count($res2)." in ".$time;
// deduped to 513333 in 0.054931879043579
Anonymous ¶
12 years ago
It's often faster to use a foreache and array_keys than array_unique:
<?php
$max = 1000000;
$arr = range(1,$max,3);
$arr2 = range(1,$max,2);
$arr = array_merge($arr,$arr2);
$time = -microtime(true);
$res1 = array_unique($arr);
$time += microtime(true);
echo "deduped to ".count($res1)." in ".$time;
// deduped to 666667 in 32.300781965256
$time = -microtime(true);
$res2 = array();
foreach($arr as $key=>$val) {
$res2[$val] = true;
}
$res2 = array_keys($res2);
$time += microtime(true);
echo "<br />deduped to ".count($res2)." in ".$time;
// deduped to 666667 in 0.84372591972351
?>
Fabiano ¶
4 years ago
As for PHP 7.1.12, this is the comparison between array_keys(array_flip()), array_flip(array_flip()), for each elimination and array_unique. The array_keys(array_flip()) is the fastest method to remove duplication values from a single dimension array:
<?php
$max = 1000000;
$arr = range(1,$max,3);
$arr2 = range(1,$max,2);
$arr = array_merge($arr,$arr2);
$time = -microtime(true);
$res1 = array_unique($arr);
$time += microtime(true);
echo "<br>deduped to ".count($res1)." in ".$time;
// deduped to 666667 in 0.78185796737671
// memory used: 33558528
$time = -microtime(true);
$res2 = array_flip(array_flip($arr));
$time += microtime(true);
echo "<br><br>deduped to ".count($res2)." in ".$time;
// deduped to 666667 in 0.072191953659058
// memory used: 3774873
$time = -microtime(true);
$res3 = array();
foreach($arr as $key=>$val) {
$res3[$val] = true;
}
$res3 = array_keys($res3);
$time += microtime(true);
echo "<br /><br>deduped to ".count($res3)." in ".$time;
// deduped to 666667 in 0.095494985580444
// memory used: 33558528
$time = -microtime(true);
$res4 = array_keys(array_flip($arr));
$time += microtime(true);
echo "<br /><br>deduped to ".count($res4)." in ".$time;
// deduped to 666667 in 0.05807900428772
// memory used: 33558528
Ray dot Paseur at SometimesUsesGmail dot com ¶
14 years ago
I needed to identify email addresses in a data table that were replicated, so I wrote the array_not_unique() function:
<?php
function array_not_unique($raw_array) {
$dupes = array();
natcasesort($raw_array);
reset ($raw_array);
$old_key = NULL;
$old_value = NULL;
foreach ($raw_array as $key => $value) {
if ($value === NULL) { continue; }
if ($old_value == $value) {
$dupes[$old_key] = $old_value;
$dupes[$key] = $value;
}
$old_value = $value;
$old_key = $key;
}
return $dupes;
}
$raw_array = array();
$raw_array[1] = 'abc@xyz.com';
$raw_array[2] = 'def@xyz.com';
$raw_array[3] = 'ghi@xyz.com';
$raw_array[4] = 'abc@xyz.com'; // Duplicate
$common_stuff = array_not_unique($raw_array);
var_dump($common_stuff);
?>
mnbayazit ¶
14 years ago
Case insensitive; will keep first encountered value.
<?php
function array_iunique($array) {
$lowered = array_map('strtolower', $array);
return array_intersect_key($array, array_unique($lowered));
}
?>
keneks at gmail dot com ¶
15 years ago
Taking the advantage of array_unique, here is a simple function to check if an array has duplicate values.
It simply compares the number of elements between the original array and the array_uniqued array.
<?php
function array_has_duplicates(array $array)
{
$uniq = array_unique($array);
return count($uniq) != count($array);
}
?>
contact at evoweb dot fr ¶
1 year ago
Here is a solution to make unique values keeping empty values for an array with keys :
<?php
function array_unique_kempty($array) {
$values = array_unique($array);
$return = array_combine(array_keys($array), array_fill(0,count($array),null));
return array_merge($return,$values);
}
$myArray = [
"test1" => "aaa",
"test2" => null,
"test3" => "aaa",
"test4" => "bbb",
"test5" => null,
"test6" => "ccc",
"test7" => "ddd",
"test8" => "ccc"
];
echo "<pre>".print_r(array_unique_kempty($myArray),true)."</pre>";
/*
Array
(
[test1] => aaa
[test2] =>
[test3] =>
[test4] => bbb
[test5] =>
[test6] => ccc
[test7] => ddd
[test8] =>
)
*/
?>
calexandrepcjr at gmail dot com ¶
5 years ago
Following the Ghanshyam Katriya idea, but with an array of objects, where the $key is related to object propriety that you want to filter the uniqueness of array:
<?php
function obj_multi_unique($obj, $key = false)
{
$totalObjs = count($obj);
if (is_array($obj) && $totalObjs > 0 && is_object($obj[0]) && ($key && !is_numeric($key))) {
for ($i = 0; $i < $totalObjs; $i++) {
if (isset($obj[$i])) {
for ($j = $i + 1; $j < $totalObjs; $j++) {
if (isset($obj[$j]) && $obj[$i]->{$key} === $obj[$j]->{$key}) {
unset($obj[$j]);
}
}
}
}
return array_values($obj);
} else {
throw new Exception('Invalid argument or your array of objects is empty');
}
}
?>
mostafatalebi at rocketmail dot com ¶
8 years ago
If you find the need to get a sorted array without it preserving the keys, use this code which has worked for me:
<?php
$array = array("hello", "fine", "good", "fine", "hello", "bye");
$get_sorted_unique_array = array_values(array_unique($array));
?>
The above code returns an array which is both unique and sorted from zero.
regeda at inbox dot ru ¶
12 years ago
recursive array unique for multiarrays
<?php
function super_unique($array)
{
$result = array_map("unserialize", array_unique(array_map("serialize", $array)));
foreach ($result as $key => $value)
{
if ( is_array($value) )
{
$result[$key] = super_unique($value);
}
}
return $result;
}
?>
sashasimkin at gmail dot com ¶
10 years ago
My object unique function:
<?php
function object_unique( $obj ){
$objArray = (array) $obj;
$objArray = array_intersect_assoc( array_unique( $objArray ), $objArray );
foreach( $obj as $n => $f ) {
if( !array_key_exists( $n, $objArray ) ) unset( $obj->$n );
}
return $obj;
}
?>
And these code:
<?php
class Test{
public $pr0 = 'string';
public $pr1 = 'string1';
public $pr2 = 'string';
public $pr3 = 'string2';
}
$obj = new Test;
var_dump( object_unique( $obj ) );
?>
returns:
object(Test)[1]
public 'pr0' => string 'string' (length=6)
public 'pr1' => string 'string1' (length=7)
public 'pr3' => string 'string2' (length=7)
agarcia at rsn dot com dot co ¶
16 years ago
This is a script for multi_dimensional arrays
<?php
function remove_dup($matriz) {
$aux_ini=array();
$entrega=array();
for($n=0;$n<count($matriz);$n++)
{
$aux_ini[]=serialize($matriz[$n]);
}
$mat=array_unique($aux_ini);
for($n=0;$n<count($matriz);$n++)
{
$entrega[]=unserialize($mat[$n]);
}
return $entrega;
}
?>
Ludovico Grossi ¶
7 years ago
[Editor's note: please note that this will not work well with non-scalar values in the array. Array keys can not be arrays themselves, nor streams, resources, etc. Flipping the array causes a change in key-name]
You can do a super fast version of array_unique directly in PHP, even faster than the other solution posted in the comments!
Compared to the built in function it is 20x faster! (2x faster than the solution in the comments).
<?php
function superfast_array_unique($array) {
return array_keys(array_flip($array));
}
?>
This works faster for small and big arrays.
quecoder at gmail ¶
13 years ago
another method to get unique values is :
<?php
$alpha=array('a','b','c','a','b','d','e','f','f');
$alpha= array_keys(array_count_values($alpha));
print_r($alpha);
?>
Output:
Array ( [0] => a [1] => b [2] => c [3] => d [4] => e [5] => f )
subhrajyoti dot de007 at gmail dot com ¶
4 years ago
Simple and clean way to get duplicate entries removed from a multidimensional array.
<?php
$multi_array = $multi_array [0];
$multi_array = array_unique($multi_array);
print_r($multi_array);
?>
jusvalceanu - SPAM at SPAM - yahoo dot com ¶
13 years ago
so .... my problem was multidimensional sort.
<?php
$new = array();
$exclude = array("");
for ($i = 0; $i<=count($attribs)-1; $i++) {
if (!in_array(trim($attribs[$i]["price"]) ,$exclude)) { $new[] = $attribs[$i]; $exclude[] = trim($attribs[$i]["price"]); }
}
?>
Array $attribs is an array contaning arrays. Each array in the $attrib array consists in multiple fields (ex: name, lenght, price, etc.) to be more simpler in speech think that $attrib is the array resulted by a search sql query done by a visitator on your online shoopping website ... (so ... each array in the $attrib is a product :P) if you want to sort only the uniq results use the above or use this:
<?php
/* Our Array of products */
$attribs[] = array(
"name" => "Test Product 1",
"length" => "42 cm",
"weight" => "0,5 kg",
"price" => "10 $",
"stock" => "100",
);
$attribs[] = array(
"name" => "Test Product 2",
"length" => "42 cm",
"weight" => "1,5 kg",
"price" => "10 $",
"stock" => "200",
);
/* The nice stuff */
$new = array();
$exclude = array("");
for ($i = 0; $i<=count($attribs)-1; $i++) {
if (!in_array(trim($attribs[$i]["price"]) ,$exclude)) { $new[] = $attribs[$i]; $exclude[] = trim($attribs[$i]["price"]); }
}
print_r($new); // $new is our sorted array
?>
Have fun tweaking this ;)) i know you will ;))
From Romania With Love
webmaster at jukkis dot net ¶
14 years ago
Another way to 'unique column' an array, in this case an array of objects:
Keep the desired unique column values in a static array inside the callback function for array_filter.
Example:
<?php
/* example object */
class myObj {
public $id;
public $value;
function __construct( $id, $value ) {
$this->id = $id;
$this->value = $value;
}
}
/* callback function */
function uniquecol( $obj ) {
static $idlist = array();
if ( in_array( $obj->id, $idlist ) )
return false;
$idlist[] = $obj->id;
return true;
}
/* a couple of arrays with second array having an element with same id as the first */
$list = array( new myObj( 1, 1 ), new myObj( 2, 100 ) );
$list2 = array( new myObj( 1, 10 ), new myObj( 3, 100 ) );
$list3 = array_merge( $list, $list2 );
$unique = array_filter( $list3, 'uniquecol' );
print_r( $list3 );
print_r( $unique );
?>
In addition, use array_merge( $unique ) to reindex.
zoolyka at gmail dot com ¶
6 years ago
I found the simplest way to "unique" multidimensional arrays as follows:
<?php
$array = array(
'a' => array(1, 2),
'b' => array(1, 2),
'c' => array(2, 2),
'd' => array(2, 1),
'e' => array(1, 1),
);
$array = array_map('json_encode', $array);
$array = array_unique($array);
$array = array_map('json_decode', $array);
print_r($array);
?>
As you can see "b" will be removed without any errors or notices.
amri [ at t] dhstudio dot eu ¶
12 years ago
I searched how to show only the de-duplicate elements from array, but failed.
Here is my solution:
<?php
function arrayUniqueElements($array)
{
return array_unique(array_diff_assoc($array1,array_unique($array1)));
};
?>
Example:
<?php
$arr1 = array('foo', 'bar', 'xyzzy', '&', 'xyzzy',
'baz', 'bat', '|', 'xyzzy', 'plugh',
'xyzzy', 'foobar', '|', 'plonk', 'xyzzy',
'apples', '&', 'xyzzy', 'oranges', 'xyzzy',
'pears','foobar');
$result=arrayUniqueElements($arr1);
print_r($result);exit;
?>
Output:
Array
(
[4] => xyzzy
[12] => |
[16] => &
[21] => foobar
)
csaba at alum dot mit dot edu ¶
18 years ago
The following is an efficient, adaptable implementation of array_unique which always retains the first key having a given value:
<?php
function array_unique2(&$aray) {
$aHash = array();
foreach ($aray as $key => &$val) if (@$aHash[$val]++) unset ($aray[$key]);
}
?>
It is also adaptable to multi dimensional arrays. For example, if your array is a sequence of (multidimensional) points, then in place of @$aHash[$val]++ you could use @$aHash[implode("X",$val)]++
If you want to not have holes in your array, you can do an array_merge($aray) at the end.
Csaba Gabor
Sbastien ¶
29 days ago
Because of PHP comparaisons modalities, you can never distinguish null from others falsy values.
Note the absorbing nature of true and false booleans in mix types array.
<?php
$a = [true, false, null, '', '0', '123', 0, 123];
foreach (['SORT_REGULAR', 'SORT_NUMERIC', 'SORT_STRING', 'SORT_LOCALE_STRING'] as $flag) {
$a_new = array_unique($a, constant($flag));
echo "{$flag} ==> ";
var_dump($a_new);
}
/*
Gives :
SORT_REGULAR ==> array(2) {
[0]=> bool(true)
[1]=> bool(false)
}
SORT_NUMERIC ==> array(3) {
[0]=> bool(true)
[1]=> bool(false)
[5]=> string(3) "123"
}
SORT_STRING ==> array(4) {
[0]=> bool(true)
[1]=> bool(false)
[4]=> string(1) "0"
[5]=> string(3) "123"
}
SORT_LOCALE_STRING ==> array(4) {
[0]=> bool(true)
[1]=> bool(false)
[4]=> string(1) "0"
[5]=> string(3) "123"
}
*/
dirk dot avery a t gmail ¶
13 years ago
Although array_unique is not intended to work with multi-dimensional arrays, it does on 5.2.9. However, it does not for 5.2.5. Beware.
Dorphalsig ¶
13 years ago
I had a problem with array_unique and multidimensional arrays ... Maybe there's a better way to do this, but this will work for any dimensional arrays.
<?php
function arrayUnique($myArray)
{
if(!is_array($myArray))
return $myArray;
foreach ($myArray as &$myvalue){
$myvalue=serialize($myvalue);
}
$myArray=array_unique($myArray);
foreach ($myArray as &$myvalue){
$myvalue=unserialize($myvalue);
}
return $myArray;
}
?>
PHP Expert ¶
14 years ago
Case insensitive for PHP v4.x and up.
<?php
function in_iarray($str, $a) {
foreach ($a as $v) {
if (strcasecmp($str, $v) == 0) {
return true;
}
}
return false;
}
function array_iunique($a) {
$n = array();
foreach ($a as $k => $v) {
if (!in_iarray($v, $n)) {
$n[$k]=$v;
}
}
return $n;
}
$input = array("aAa","bBb","cCc","AaA","ccC","ccc","CCC","bBB","AAA","XXX");
$result = array_iunique($input);
print_r($result);
/*
Array
(
[0] => aAa
[1] => bBb
[2] => cCc
[9] => XXX
)
*/
?>
geuis dot teses at gmail dot com ¶
15 years ago
Here's the shortest line of code I could find/create to remove all duplicate entries from an array and then reindex the keys.
<?php
// Fruits, vegetables, and other food:
$var = array('apple','banana','carrot','cat','dog','egg','eggplant','fish');
$var = array_values(array_unique($var));
?>
memandeemail at gmail dot com ¶
16 years ago
Problem:
I have loaded an array with the results of a database
query. The Fields are 'FirstName' and 'LastName'.
I would like to find a way to contactenate the two
fields, and then return only unique values for the
array. For example, if the database query returns
three instances of a record with the FirstName John
and the LastName Smith in two distinct fields, I would
like to build a new array that would contain all the
original fields, but with John Smith in it only once.
Thanks for: Colin Campbell
Solution:
<?php
/**
* The same thing than implode function, but return the keys so
*
* <code>
* $_GET = array('id' => '4587','with' => 'key');
* ...
* echo shared::implode_with_key('&',$_GET,'='); // Resultado: id=4587&with=key
* ...
* </code>
*
* @param string $glue Oque colocar entre as chave => valor
* @param array $pieces Valores
* @param string $hifen Separar chave da array do valor
* @return string
* @author memandeemail at gmail dot com
*/
function implode_with_key($glue = null, $pieces, $hifen = ',') {
$return = null;
foreach ($pieces as $tk => $tv) $return .= $glue.$tk.$hifen.$tv;
return substr($return,1);
}
/**
* Return unique values from a tree of values
*
* @param array $array_tree
* @return array
* @author memandeemail at gmail dot com
*/
function array_unique_tree($array_tree) {
$will_return = array(); $vtemp = array();
foreach ($array_tree as $tkey => $tvalue) $vtemp[$tkey] = implode_with_key('&',$tvalue,'=');
foreach (array_keys(array_unique($vtemp)) as $tvalue) $will_return[$tvalue] = $array_tree[$tvalue];
return $will_return;
}
$problem = array_fill(0,3,
array('FirstName' => 'John', 'LastName' => 'Smith')
);
$problem[] = array('FirstName' => 'Davi', 'LastName' => 'S. Mesquita');
$problem[] = array('FirstName' => 'John', 'LastName' => 'Tom');
print_r($problem);
print_r(array_unique_tree($problem));
?>
备份地址：http://www.lvesu.com/blog/php/function.array-unique.php