array_unique
(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)
array_unique — 配列から重複した値を削除する
説明
array
を入力とし、値に重複のない新規配列を返します。
キーは保持されることに注意してください。
指定された flags
において、
複数の要素が等しかった場合、はじめの要素のキーと値が保持されます。
注意:
(string) $elem1 === (string) $elem2
の場合のみ二つの要素は等しいとみなされます。 つまり、文字列表現が同じである場合は、最初の要素を使用します。
パラメータ
array
-
入力の配列。
flags
-
オプションの 2 番目のパラメータ
flags
にこれらの値を使用して、比較の挙動を変更します。比較形式のフラグは次のとおりです。
-
SORT_REGULAR
- 通常の比較 (型変換をしない) を行います -
SORT_NUMERIC
- 数値として比較します -
SORT_STRING
- 文字列として比較します -
SORT_LOCALE_STRING
- 現在のロケールにもとづいて文字列として比較します。
-
戻り値
処理済の配列を返します。
変更履歴
バージョン | 説明 |
---|---|
7.2.0 |
flags が SORT_STRING の場合、
新しい配列が生成され、ユニークな要素が追加されるようになりました。
これによって、異なった数値のインデックスが振られる可能性があります。
これより前のバージョンでは、 array がコピーされ、
(配列を後にパックせずに) ユニークでない値が削除されていました。
|
例
例1 array_unique() の例
<?php
$input = array("a" => "green", "red", "b" => "green", "blue", "red");
$result = array_unique($input);
print_r($result);
?>
上の例の出力は以下となります。
Array ( [a] => green [0] => red [1] => blue )
例2 array_unique() と型
<?php
$input = array(4, "4", "3", 4, 3, "3");
$result = array_unique($input);
var_dump($result);
?>
上の例の出力は以下となります。
array(2) { [0] => int(4) [2] => string(1) "3" }
注意
注意: array_unique() は、 多次元配列での使用を想定したものではないことに注意しましょう。
+add a note
User Contributed Notes 33 notes
Ghanshyam Katriya(anshkatriya at gmail) ¶
9 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"),
);
?>
Mike D. - michal at euro-net.pl ¶
1 year ago
modified code originally posted by Ghanshyam Katriya(anshkatriya at gmail) [highest voted comment here].
1. In php 7.4 counter $i breaks the function. Removed completely (imo was waste of keystrokes anyway).
2. I added second return value - array of duplicates. So you can take both and compare them (I had to).
Example array (copy-paste from original post):
<?php
$details = array(
0 => array("id"=>"1", "name"=>"Mike", "num"=>"9876543210"),
1 => array("id"=>"2", "name"=>"Carissa", "num"=>"08548596258"),
2 => array("id"=>"1", "name"=>"Mathew", "num"=>"784581254"),
);
?>
Function:
<?php
function unique_multidim_array($array, $key) : array {
$uniq_array = array();
$dup_array = array();
$key_array = array();
foreach($array as $val) {
if (!in_array($val[$key], $key_array)) {
$key_array[] = $val[$key];
$uniq_array[] = $val;
/*
# 1st list to check:
# echo "ID or sth: " . $val['building_id'] . "; Something else: " . $val['nodes_name'] . (...) "\n";
*/
} else {
$dup_array[] = $val;
/*
# 2nd list to check:
# echo "ID or sth: " . $val['building_id'] . "; Something else: " . $val['nodes_name'] . (...) "\n";
*/
}
}
return array($uniq_array, $dup_array, /* $key_array */);
}
?>
Usage:
<?php
list($unique_addresses, $duplicates, /* $unique_keys */) = unique_multidim_array($details,'id');
?>
Then:
var_dump($unique_addresses);
or
var_dump($duplicates);
or foreach or whatever. Personally I just echo-ed 1st and then 2nd (both DOUBLE COMMENTED) list in function itself (then copied both to notepad++ and compared them - just to be 100% sure), but in case you want to do something else with it - enjoy :)
Plus - as a bonus - you also get an array of UNIQUE keys you searched for (just uncomment >$key_array< in both: function return and function call code).
From example array code returns:
var_dump($unique_addresses);
array(2) {
[0]=>
array(3) {
["id"]=>
string(1) "1"
["name"]=>
string(4) "Mike"
["num"]=>
string(10) "9876543210"
}
[1]=>
array(3) {
["id"]=>
string(1) "2"
["name"]=>
string(7) "Carissa"
["num"]=>
string(11) "08548596258"
}
}
var_dump($duplicates);
array(1) {
[0]=>
array(3) {
["id"]=>
string(1) "1"
["name"]=>
string(6) "Mathew"
["num"]=>
string(9) "784581254"
}
}
Plus keys, if you want.
P.S.: in my - practical - case of DB querying I got around 4k uniques and 15k dupes :)
falundir at gmail dot com ¶
6 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)]
?>
Anonymous ¶
14 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
?>
stoff@ ¶
7 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
calexandrepcjr at gmail dot com ¶
7 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');
}
}
?>
Ray dot Paseur at SometimesUsesGmail dot com ¶
16 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);
?>
free dot smilesrg at gmail dot com ¶
1 year ago
$a = new StdClass();
$b = new StdClass();
var_dump(array_unique([$a, $b, $b, $a], SORT_REGULAR));
//array(1) {
// [0]=>
// object(stdClass)#1 (0) {
// }
//}
$a->name = 'One';
$b->name = 'Two';
var_dump(array_unique([$a, $b, $b, $a], SORT_REGULAR));
//array(2) {
// [0]=>
// object(stdClass)#1 (1) {
// ["name"]=>
// string(3) "One"
// }
// [1]=>
// object(stdClass)#2 (1) {
// ["name"]=>
// string(3) "Two"
// }
//}
contact at evoweb dot fr ¶
3 years ago
Here is a solution to make unique values keeping empty values for an array with keys :
<?php
function array_unique_kempty($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] =>
)
*/
?>
mnbayazit ¶
16 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($lowered));
}
?>
PHP Expert ¶
16 years ago
Case insensitive for PHP v4.x and up.
<?php
function in_iarray($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
)
*/
?>
sashasimkin at gmail dot com ¶
12 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)
Victoire Nkolo at crinastudio.com ¶
1 year ago
<?php
//removes duplicated objetcs from an array according to the property given
class ArrayFilter
{
public static function dedupe_array_of_objets(array $array, string $property) : array
{
$i = 0;
$filteredArray = array();
$keyArray = array();
foreach($array as $item) {
if (!in_array($item->$property, $keyArray)) {
$keyArray[$i] = $item->$property;
$filteredArray[$i] = $item;
}
$i++;
}
return $filteredArray;
}
}
mostafatalebi at rocketmail dot com ¶
10 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.
Dorphalsig ¶
16 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 $myArray;
}
?>
regeda at inbox dot ru ¶
14 years ago
recursive array unique for multiarrays
<?php
function super_unique($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 $result;
}
?>
agarcia at rsn dot com dot co ¶
18 years ago
This is a script for multi_dimensional arrays
<?php
function remove_dup($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;
}
?>
keneks at gmail dot com ¶
18 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);
}
?>
quecoder at gmail ¶
16 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 )
jusvalceanu - SPAM at SPAM - yahoo dot com ¶
15 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 ¶
17 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.
Fabiano ¶
6 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
zoolyka at gmail dot com ¶
8 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.
subhrajyoti dot de007 at gmail dot com ¶
6 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);
?>
geuis dot teses at gmail dot com ¶
18 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));
?>
amri [ at t] dhstudio dot eu ¶
14 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
)