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Last updated: Sat, 27 Jan 2007

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# array_unique

(PHP 4 >= 4.0.1, PHP 5)

array_unique -- Убрать повторяющиеся значения из массива

## Описание

array array_unique ( array array )

array_unique() берёт в качестве параметра `array` и возвращает новый массив без повторяющихся значений.

Обратите внимание, что ключи сохранятся. array_unique() сначала сортирует значения как строки, сохраняет первый встреченный ключ для каждого значения и игнорирует все последующие ключи. Это не означает, что первый ключ каждого значения неотсортированного `array` будет сохранён.

> Замечание: Два элемента считаются одинаковыми в том и только в том случае, если `(string) $elem1 === (string) $elem2`. Другими словами: если у них одинаковое строковое представление.

> Будет использован первый элемент.

Пример 1. Пример использования array_unique()

`<?php $input = array("a" => "green", "red", "b" => "green", "blue", "red"); $result = array_unique($input); print_r($result); ?>`

Вывод:

`Array
(
[a] => green
[0] => red
[1] => blue
)`

Пример 2. array_unique() и типы:

`<?php $input = array(4, "4", "3", 4, 3, "3"); $result = array_unique($input); var_dump($result); ?>`

Скрипт выведет:

`array(2) { [0] => int(4) [2] => string(1) "3" }`

add a note User Contributed Notes
array_unique
n@cho NOSPAM cofrepuntonet
13-Dec-2006 02:45
`What if I only want the duplicated items, not the unique ones?
I tried to do it by using array_diff of an array and its unique, but it did not work (any help?); so I made this function with a relatively good efficiency:
function array_repeated($array) {
if(!is_array($array)) return false;
$repeated_values = Array();
$array_unique = array_unique($array);
if(count($array)-count($array_unique)) {
for($i=0;$i<count($array);$i++) {
if(!array_key_exists($i, $array_unique)) $repeated_values[] = $array[$i];
}
}
return $repeated_values;
}
This function is based on the behaviour of the array_unique function that mantains the indexes of the array when deleting the item.`
n@cho NOSPAM cofrepuntonet
13-Dec-2006 02:26
`Note that array_unique preserves the keys, even if the array is not associative:
$values = Array("john@hotmail.com", "peter@hotmail.com", "will@hotmail.com", "john@hotmail.com", "laura@hotmail.com", "mariah@hotmail.com");
echo "<br>".count($values)." values.<br>";
var_dump($values);
$unique_values = array_unique($values);
echo "<br>".count($unique_values)." unique values.<br>";
var_dump($unique_values);
RESULT:
6 values.
array(6) {
[0]=>
string(16) "john@hotmail.com"
[1]=>
string(17) "peter@hotmail.com"
[2]=>
string(16) "will@hotmail.com"
[3]=>
string(16) "john@hotmail.com"
[4]=>
string(17) "laura@hotmail.com"
[5]=>
string(18) "mariah@hotmail.com"
}
5 unique values.
array(5) {
[0]=>
string(16) "john@hotmail.com"
[1]=>
string(17) "peter@hotmail.com"
[2]=>
string(16) "will@hotmail.com"
[4]=>
string(17) "laura@hotmail.com"
[5]=>
string(18) "mariah@hotmail.com"
}
$unique_values[3] is missing. Use array_merge or array_values if you need the index to be linear.`
arr1
01-Nov-2006 08:59
`Just to note that array_unique, treats null values as none unique values. So if your using array_unique to detect duplicate values it will also detect multiple null values.`
Ome_Henk
27-Oct-2006 12:16
`For people looking at the flip flip method for getting unique values in a simple array. This is the absolute fastest method:
$unique = array_keys(array_flip($array));
It's marginally faster as $unique = array_merge(array_flip(array_flip($array)));
And it's marginally slower as $unique array_flip(array_flip($array)) which leaves gaps.
It's still about twice as fast or fast as array_unique.
This tested on several different machines with 100000 random arrays. All machines used a version of PHP5.`
geuis dot teses at gmail dot com
09-Oct-2006 10:27
`Here's the shortest line of code I could find/create to remove all duplicate entries from an array and then reindex the keys.
//$var is an array. This example its one-dimensional. Your most basic kind of array.
$var = array_values(array_unique($var));`
geuis dot teses at gmail dot com
09-Oct-2006 09:53
`Sorry to repost this but it was helpful and took a while to find all the way down.
Ric
05-Apr-2005 09:44
A very simple way of getting rid of duplicate entries and re-indexing with key starting at 0:
$temp=array_unique($main);
$main=array_values($temp);`
keneks at gmail dot com
30-Sep-2006 07:01
`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.
function array_search_dups($array)
{
$dup_array = $array;
$dup_array = array_unique($dup_array);
if(count($dup_array) != count($array))
{
return TRUE;
}
else
{
return FALSE;
}
}`
pulsarkowy at NOSPAM dot gmail dot com
13-Sep-2006 04:30
`This function below will remove multiple values from array, remove 'empty' fields an also count how many times the given value occured.
it's rather slow and not 'elegant' but works.
usage:
$myarray=my_array_unique($myarray)
in return it produces an 3 fields array:
1st is index number, 2nd is the value, 3rd is counter.
function my_array_unique($tablica)
{
$tnum=count($tablica);
$i=1;
$k=1;
$t[1]['product']="";
$t[1]['count']=1;
while($i<=$tnum) {
if (!array_multi_search($tablica[$i], $t)) {
$t[$k]['product']=$tablica[$i];
$t[$k]['count']=1;
$k++;
}
else {
$y=1;
while ($y<=count($t)) {
if ($t[$y]['product']==$tablica[$i])
$t[$y]['count']++;
$y++;
}
}
$i++;
}
$tablica=$t;
return $tablica;
};
the function uses another function that i've found on the php.net site (i'm posting it only for informational reasons - i can't remember who wrote it):
function array_multi_search( $p_needle, $p_haystack )
{
if( !is_array( $p_haystack ) )
{
return false;
}
if( in_array( $p_needle, $p_haystack ) )
{
return true;
}
foreach( $p_haystack as $row )
{
if( array_multi_search( $p_needle, $row ) )
{
return true;
}
}
return false;
}`
jacob dot bates at gmail dot com
16-Aug-2006 03:25
`In response to muddmonkey's flip-flip method, i would like to note that using this method as-is leaves the array with gaps. For example, if we have an array like this:
Array
(
[0] => 1
[1] => 1
[2] => 1
)
And you apply the flip-flip method, you get this:
Array
(
[2] => 1
)
If you apply the array_merge function to the result, it closes these gaps without seriously sacrificing performance. I wrote some test code that would result in a unique array that has 10,000 elements so that the impact of array_merge was more evident. Here is my test code:
function microtime_float(){ //timing (stolen from muddmonkey)
list($usec, $sec) = explode(" ", microtime());
return ((float)$usec + (float)$sec);
}
//make an array and fill it up
$final=array();
for($i=0;$i<50000;$i++){
$final[]=$i%10000; //make sure the unique array has 10000 elements
}
//try flip-flip
$start1 = microtime_float();
array_flip(array_flip($final));
$stop1=microtime_float();
echo($stop1-$start1.' (flip-flip)<br>');
//try my flip-flip-merge
$start2=microtime_float();
array_merge(array_flip(array_flip($final)));
$stop2=microtime_float();
echo($stop2-$start2.' (flip-flip-merge)<br />');
//try array_unique
$start3=microtime_float();
array_unique($final);
$stop3=microtime_float();
echo($stop3-$start3.' (array_unique)<br />');
Here was the result:
0.14240193367004 (flip-flip)
0.18947601318359 (flip-flip-merge)
3.7108051776886 (array_unique)
As you can see, flip-flip-merge slows it down a little, but both are still way faster than array_unique.`
KoKos
03-Aug-2006 02:27
`In response to muddmonkey@harveyMcoldotedu (yeah, i know i'm a bit too late :D )
In your example you're using the "flip-flip" AFTER doing the array_unique() already. That's why it is so fast. ;)`
a dot fotoglidis at 7mbit dot net
23-Jul-2006 08:25
`In addition to brettz9's remove_dups:
This one will actually take a multi-dimensional array and return it minus the duplicates in regard to the specified element of the inner arrays.
<?php
/*
Initialising new array to the first element of the given array.
Check whether current element in initial array has already been added to new array.
If yes break to save us some time. If no, then add current element to new array.
*/
function remove_dups($array, $row_element) {
$new_array[0] = $array[0];
foreach ($array as $current) {
$add_flag = 1;
foreach ($new_array as $tmp) {
if ($current[$row_element]==$tmp[$row_element]) {
$add_flag = 0; break;
}
}
if ($add_flag) $new_array[] = $current;
}
return $new_array;
} // end function remove_dups
?>
______________________________________________
EXAMPLE
<?php
$array[0] = array('Charles','Wade',233);
$array[1] = array('Charles','Watson',234);
$array[2] = array('Tom','Wade',235);
$array = remove_dups($array,0);
?>
The above example will output:
Array
(
[0] => Array ([0] => 'Charles' [1] => 'Wade' [2] => 233)
[1] => Array ([0] => 'Tom' [1] => 'Wade' [2] => 235)
)
<?php
remove dups($array,1);
?>
will output:
Array
(
[0] => Array ([0] => 'Charles' [1] => 'Wade' [2] => 233)
[1] => Array ([1] => 'Charles' [1] => 'Watson' [2] => 234)
)
At each case it removes all inner arrays that have a duplicate in the specified position and keeps the first inner array only.`
uditsawhney at yahoo dot com
15-Jul-2006 12:14
`<?php
//Fn for array_unique column-wise for multi-dimensioanl array without losing keys | Start
function array_uniquecolumn($arr)
{
$rows = sizeof($arr);
$columns = sizeof($arr[0]);
$columnkeys = array_keys($arr[0]);
for($i=0; $i<$columns; $i++)
{
for($j=0;$j<$rows;$j++)
{
for($k = $j+1; $k<$rows; $k++)
{
if($arr[$j][$columnkeys[$i]] == $arr[$k][$columnkeys[$i]])
$arr[$k][$columnkeys[$i]] = "";
}
}
}
return ($arr);
}
//Fn for array_unique column-wise for multi-dimensioanl array without losing keys | Stop
$arrUGCourse[]= array( "CTR" => "1",
"UGCOURSE"=>"ABC",
"TSINITIATE"=>"540",
"COUNT"=>"34",
"ENTRY_DT"=>"2006-05-01",
"CUMULATIVE"=> 44);
$arrUGCourse[]= array( "CTR" => "2",
"UGCOURSE"=>"ABC",
"TSINITIATE"=>"5401",
"COUNT"=>"341",
"ENTRY_DT"=>"2006-05-11",
"CUMULATIVE"=> 44);
print_r(array_uniquecolumn($arrUGCourse));
?>`
davin at baragiotta dot org
19-Apr-2006 03:52
`I used the code submitted by "agarcia" regarding multi-dimensional arrays but keys with no data were still there. I've just added a line to completely unset the redondant part of the array so it is now acting like array_unique.
<?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[$n]);
}
foreach ($entrega as $key => $row){
if (!is_array($row)) { unset($entrega[$key]); }
}
return $entrega;
}
?>
Thanks!
Davin Baragiotta`
MoD
14-Apr-2006 09:02
`The shortest way i found to remove duplicate array from a column,
For example if you parse Multiple XML sources, you can remove duplicate items that contain the same link.
<?PHP
function remove_duplicate($array, $field)
{
foreach ($array as $sub)
$cmp[] = $sub[$field];
$unique = array_unique($cmp);
foreach ($unique as $k => $rien)
$new[] = $array[$k];
return $new;
}
?>`
agarcia at rsn dot com dot co
31-Mar-2006 12:41
`This is a script for multi_dimensional arrays
function remove_dup($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 $entrega;
}`
brettz9
09-Mar-2006 12:51
`If you have a multi-dimensional array and wish to remove duplicates from a particular "column" as well as the corresponding values in the other "columns", you might find the following helpful.
<?php
function remove_dups($array, $index) {
$array_count = count($array);
$array_count_inner = count($array[$index]);
for ($i=0; $i<$array_count_inner; $i++) {
for ($j=$i+1; $j<$array_count_inner; $j++) {
if ($array[$index][$i]==$array[$index][$j]) {
for ($k=0; $k<$array_count; $k++) {
unset($array[$k][$i]);
} // end for
} // end if
} // end for
} // end for
return $array;
} // end function remove_dups
?>`
mcmeijer at yahoo dot com
27-Jan-2006 05:18
`This is a recursive arrayUnique function for arrays of any dimension. (tested with 4-dimensional array)
The line '$newArray=deleteEmpty($newArray);' is optional and removes empty keys and values
<?php
function arrayUnique($myArray)
{
$newArray = Array();
if (is_array($myArray))
{
foreach($myArray as $key=>$val)
{
if (is_array($val))
{
$val2 = arrayUnique($val);
}
else
{
$val2 = $val;
$newArray=array_unique($myArray);
$newArray=deleteEmpty($newArray);
break;
}
if (!empty($val2))
{
$newArray[$key] = $val2;
}
}
}
return ($newArray);
}
function deleteEmpty($myArray)
{
$retArray= Array();
foreach($myArray as $key=>$val)
{
if (($key<>"") && ($val<>""))
{
$retArray[$key] = $val;
}
}
return $retArray;
}
?>`
idefix at idefix dot ath dot cx
04-Jan-2006 02:49
`in reply to memandeemail at gmail dot com:
imo it would be easier to do these things in your SQL statement.
ex.:
SELECT na1.FirstName, na1.LastName
FROM names na1, names na2
WHERE na1.FirstName = na2.FirstName
AND na1.LastName = na2.LastName
AND na1.id < na2.id;`
memandeemail at gmail dot com
03-Jan-2006 10:47
`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:
/**
* 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($problem));`
webcreator at centrum dot cz
28-Oct-2005 04:25
`array_unique function starts its comparation from beginning and pop the key off if there is more values inside array. The last one remains. But i needed to hold priority of the order of values and let the first one in.
Here is my easy solution:
##---
function my_array_unique($from)
{
for ($i=count($from);$i>1;$i--)
{
$last = $from[$i];
$from[$i] = "";
if (!in_array($last,$from))
$from[$i]=$last;
}
return array_unique($from);
}
# One empty value remains in array.
# But its very easy to separate it while using output array.`
kenrbnsn at rbnsn dot com
26-Sep-2005 09:09
`Yet another Array_Unique for multi-demensioned arrays. I've only tested this on two-demensioned arrays, but it could probably be generalized for more, or made to use recursion.
This function uses the serialize, array_unique, and unserialize functions to do the work.
<?php
function multi_unique($array) {
foreach ($array as $k=>$na)
$new[$k] = serialize($na);
$uniq = array_unique($new);
foreach($uniq as $k=>$ser)
$new1[$k] = unserialize($ser);
return ($new1);
}
?>`
passtschu AT freenet DOT de
21-Sep-2005 07:20
`array_unique for multidimensional arrays. similar to the DISTINCT in SQL function.
the function can group, sum and count keys
<?PHP
/*
$array - nothing to say
$group_keys - columns which have to be grouped - can be STRING or ARRAY (STRING, STRING[, ...])
$sum_keys - columns which have to be summed - can be STRING or ARRAY (STRING, STRING[, ...])
$count_key - must be STRING - count the grouped keys
*/
function array_distinct ($array, $group_keys, $sum_keys = NULL, $count_key = NULL){
if (!is_array ($group_keys)) $group_keys = array ($group_keys);
if (!is_array ($sum_keys)) $sum_keys = array ($sum_keys);
$existing_sub_keys = array ();
$output = array ();
foreach ($array as $key => $sub_array){
$puffer = NULL;
#group keys
foreach ($group_keys as $group_key){
$puffer .= $sub_array[$group_key];
}
$puffer = serialize ($puffer);
if (!in_array ($puffer, $existing_sub_keys)){
$existing_sub_keys[$key] = $puffer;
$output[$key] = $sub_array;
}
else{
$puffer = array_search ($puffer, $existing_sub_keys);
#sum keys
foreach ($sum_keys as $sum_key){
if (is_string ($sum_key)) $output[$puffer][$sum_key] += $sub_array[$sum_key];
}
#count grouped keys
if (!array_key_exists ($count_key, $output[$puffer])) $output[$puffer][$count_key] = 1;
if (is_string ($count_key)) $output[$puffer][$count_key]++;
}
}
return $output;
}
?>`
muddmonkey@harveyMcoldotedu
17-Aug-2005 01:44
`If you're doing numeric arrays etc. I found flip-flip to work much better than array_unique:
<?PHP
function microtime_float(){ //timing
list($usec, $sec) = explode(" ", microtime());
return ((float)$usec + (float)$sec);
}
//make an arry and fill it up
$final=array();
for($i=0;$i<50000;$i++){
$final[]=$i%13; //make sure there are some dupes
}
//try array unique
$start1 = microtime_float();
array_unique($final);
$stop1=microtime_float();
echo($stop1-$start1.'<br>');
//try my flip-flip
$start2=microtime_float();
array_flip(array_flip($final));
$stop2=microtime_float();
echo($stop2-$start2);
?>
Running this with only ints in the array (as above) I get runtimes such as:
1.6195669174194 (using unique)
0.017037868499756 (using flip flip)
which is two orders of magnitude faster!
Appending a string:
($final[]='test'.$i%13;)
gives:
0.42909598350525 (using unique)
0.023258924484253 (using flip-flip)
Which is not AS great, but still 20x faster than unique.
In both cases the flip-flip seems to use less memory than the unique.
Granted the flip-flip doesn't work for all cases, but if you're doing simple stuff like this, the flip-flip will give you better run times.
~JF`
Christoph Ziegenberg
17-Jun-2005 11:44
`If the array key is a string it might be important to keep it although the value is the same (as I need it at the moment). So I wrote a function which also returns array elements which have the same value but different string keys.
function array_unique_numeric ($arr)
{
$str = $int = array();
foreach(array_keys($arr) as $key) {
${(is_int($key)?'int':'str')}[$key] = $arr[$key];
}
return array_merge($str, array_unique($int));
}
// typical array after an array_merge()...
$array = array("a" => "green", "b" => "brown", "c" => "blue", "red", "d" => "green", "yellow", "red");
print_r(array_unique($array));
// Array
// (
// [a] => green
// [b] => brown
// [c] => blue
// [0] => red
// [1] => yellow
// )
print_r(array_unique_numeric($array));
// Array
// (
// [a] => green
// [b] => brown
// [c] => blue
// [d] => green
// [0] => red
// [1] => yellow
// )`
cdblog at gmail dot com
20-May-2005 12:59
`<?php
/**
* @param string
* @return array
* @author Cocol
* @desc generate unique keywords
* for more detail please visit http://php.clickz.cn/articles/array/array_unique.html
*/
function keyword_unique($url = "") {
$unique = array(
'words' => array(),
'times' => array(),
);
$buffer = @file_get_contents($url);
$words1 = str_word_count(strtolower(strip_tags($buffer)),1);
$unique['words'] = array_unique($words1);
foreach ($words1 as $key=>$val) {
if (!in_array($val,$unique['words'])) {
$unique['times'][] = 1;
} else {
$i = array_search($val,$unique['words']);
$unique['times'][$i] += 1;
}
}
array_multisort($unique['times'],SORT_DESC,$unique['words']);
return $unique;
}
$keywords = keyword_unique("http://php.clickz.cn/");
print_r($keywords);
?>`
memandeemail at gmail dot com
15-Apr-2005 01:46
`/**
* Removes duplicate keys from an array
*
* @param array $array
* @return array
*/
function array_unique_key($array) {
$result = array();
foreach (array_unique(array_keys($array)) as $tvalue) {
$result[$tvalue] = $array[$tvalue];
}
return $result;
}`
Ric
05-Apr-2005 09:44
`A very simple way of getting rid of duplicate entries and re-indexing with key starting at 0:
$temp=array_unique($main);
$main=array_values($temp);`
trigger at e-mail dot ru
03-Feb-2005 02:53
`Just a simple implementation for JavaScript:
function array_unique(thearray)
{
thearray.sort();
//reset($thearray);
newarray = new Array();
for (n=0;n<thearray.length;n++)
{
unique=1;//by default
for(nn=0;nn<newarray.length;nn++)
if (thearray[n] == newarray[nn])
{
unique=0;//already exists
break;
}
if(unique)//dont exists
newarray.push(thearray[n]);
}
return newarray;
}`
lucas.bickel AT purplehaze DOT ch
26-Oct-2004 08:39
`I quite like the following code for making multidimensional arrays unique:
foreach ($arrAddressList AS $key => $arrAddress) {
$arrAddressList[$key] = serialize($arrAddress);
}
$arrAddressList = array_unique($arrAdressList);
foreach ($arrAddressList AS $key => $strAddress) {
$arrAddressList[$key] = unserialize($strAddress);
}
This gets me a unique array while not minding wether the the original array contains arrays or just strings (or whatever...).`
Vary
07-Oct-2004 01:24
`This script will unique the array and count the times appearance.
find more information at http://php.scmtv.com/`
justin at redwiredesign dot com
14-Sep-2004 06:23
`OK, so here's my version that maintains index integrity:
function array_unique($array)
{
$out = array();
// loop through the inbound
foreach ($array as $key=>$value) {
// if the item isn't in the array
if (!in_array($value, $out)) {
// add it to the array
$out[$key] = $value;
}
}
return $out;
}`
wernerlistas at terra dot com dot br
16-Jun-2004 08:50
`Following the code copies of a little function I've wrote that actually works with multidimensional arrays.
It also resets the array indexes.
<?php
if ( !function_exists( "arrayUnique" ) ){
function arrayUnique ( $rArray ){
$rReturn = array ();
while ( list( $key, $val ) = each ( $rArray ) ){
if ( !in_array( $val, $rReturn ) )
array_push( $rReturn, $val );
}
return $rReturn;
}
}
?>`
csaba at alum dot mit dot edu
09-Jun-2004 07:17
`The following is an efficient, adaptable implementation of array_unique which always retains the first key having a given value:
<?php
function array_unique2(&$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($aray) at the end.
Csaba Gabor`
patrikG at home dot net
11-Mar-2004 07:05
`If you need to have the keys of the duplicates in an array returned, you may find this function useful:
<?php
function unique_events($array){
//checks $array for duplicate values and returns an
//array containing the keys of duplicates
$count= array_intersect_assoc($array, array_flip( array_count_values($array)));
foreach($array as $key=>$value){
if (in_array($value,$count)){
$return[$value][]=$key;
}
}
return $return;
}
?>
Example:
Input:
Array
(
[0] => 44
[1] => 23
[2] => 23
[3] => 23
[4] => 9
[5] => 9
[6] => 9
[7] => 9
[8] => 9
[9] => 9
[10] => 9
[11] => 9
)
Function returns:
Array
(
[23] => Array
(
[0] => 1
[1] => 2
[2] => 3
)
[9] => Array
(
[0] => 4
[1] => 5
[2] => 6
[3] => 7
[4] => 8
[5] => 9
[6] => 10
[7] => 11
)
)`
bitmore.co.kr
19-Feb-2004 03:53
`//Modify
Object Unique
<?php
class foo {
var $_name;
var $_age;
function foo($name,$age=NULL) { $this->_name = $name; $this->_age = $age; }
//function get() { return $this->_name; }
//function set($name,$age=NULL) { $this->_name = $name; $this->_age = $age; }
}
function DistinctOn ($obj, $item) {
$out = array();
$list = array();
foreach ($obj as $key=>$so) {
if (!in_array($so->$item, $list)) {
echo "key = $key,so = $so,item = $item,IFlist = ";print_r($list);echo "<br>";
$list[] = $so->$item;//�����迭
$out[$key] = $so;
}
echo "Forlist = ";print_r($list);echo "<br>";
}
return $out;
}
$foo_obj[0] = new foo('tom',20);
$foo_obj[1] = new foo('paul',66);
$foo_obj[2] = new foo('tom',23);
$item = '_name';
$result = DistinctOn ($foo_obj, $item);
while(list($k,$v) = each($result)) {
print "K = ";print_r($k);
print ",V = ";print_r($v);
print "<br>";
}
//key = 0,so = Object,item = _name,IFlist = Array ( ) ,Forlist = Array ( [0] => tom )
//key = 1,so = Object,item = _name,IFlist = Array ( [0] => tom ) ,Forlist = Array ( [0] => tom [1] => paul )
//Forlist = Array ( [0] => tom [1] => paul )
//K = 0,V = foo Object ( [_name] => tom [_age] => 20 )
//K = 1,V = foo Object ( [_name] => paul [_age] => 66 )
print "<br><br>";
$item = '_age';
$result = DistinctOn ($foo_obj, $item);
while(list($k,$v) = each($result)) {
print "K = ";print_r($k);
print ",V = ";print_r($v);
print "<br>";
}
//key = 0,so = Object,item = _age,IFlist = Array ( ) ,Forlist = Array ( [0] => 20 )
//key = 1,so = Object,item = _age,IFlist = Array ( [0] => 20 ) ,Forlist = Array ( [0] => 20 [1] => 66 )
//key = 2,so = Object,item = _age,IFlist = Array ( [0] => 20 [1] => 66 ) ,
// Forlist = Array ( [0] => 20 [1] => 66 [2] => 23 )
//K = 0,V = foo Object ( [_name] => tom [_age] => 20 )
//K = 1,V = foo Object ( [_name] => paul [_age] => 66 )
//K = 2,V = foo Object ( [_name] => tom [_age] => 23 )
?>`
matt at remove_mehsmx dot com
17-Feb-2004 04:57
`Note that
<?php
array_unique($anyarray);
?>
does not do anything, unlike other array functions such as
<?php
sort($anyarray);
?>
You have to use something like:
<?php
$anyarray = array_unique($anyarray);
?>`
14-Jan-2004 05:23
`this simple function is similar based on to the function unique_multi_array posted by tru at ascribedata dot com, but will work for objects rather than arrays. use 2d objects. Its eg useful to work with mysql queries since in recent versions, the DISTINCT option in mysql selects will only work when selecting a single (not more) row.
eg.
foo_obj[0]: name: 'tom', age: '20'
foo_obj[1]: name: 'paul', age: '66'
foo_obj[2]: name: 'tom', age: '23'
foo_obj = DistinctOn ($foo_obj, $item) will return
foo_obj[0]: name: 'tom', age: '20'
foo_obj[1]: name: 'paul', age: '66'
<?php
function DistinctOn ($obj, $item) {
$out = array();
$list = array();
foreach ($obj as $key=>$so) {
if (!in_array($so->$item, $list)) {
$list[] = $so->$item;
$out[$key] = $so;
}
}
return $out;
}
?>`
tru at ascribedata dot com
16-Oct-2003 04:40
`Here's a function to make a multi-dimensional array have only DISTINCT values for a certain "column". It's like using the DISTINCT parameter on a SELECT sql statement.
<?php
function unique_multi_array($array, $sub_key) {
$target = array();
$existing_sub_key_values = array();
foreach ($array as $key=>$sub_array) {
if (!in_array($sub_array[$sub_key], $existing_sub_key_values)) {
$existing_sub_key_values[] = $sub_array[$sub_key];
$target[$key] = $sub_array;
}
}
return $target;
}
?>`
kay_rules at yahoo dot com
24-May-2003 02:28
`this function will return an array with unique value and proper key increment start from 0.
<?php
/*******************************/
function my_array_unique($somearray){
$tmparr = array_unique($somearray);
$i=0;
foreach ($tmparr as $v) {
$newarr[$i] = $v;
$i++;
}
return $newarr;
}
/********************************/
?>
eg:
<?php
$foo_arr[0] ='aa'
$foo_arr[1] ='bb'
$foo_arr[2] ='cc'
$foo_arr[3] ='bb'
$foo_arr[4] ='aa'
$foo_arr[5] ='dd'
?>
normal array_unique will return:
<?php
$foo_arr[0] ='aa';
$foo_arr[1] ='bb';
$foo_arr[2] ='cc';
$foo_arr[3] ='';
$foo_arr[4] ='';
$foo_arr[5] ='dd'
?>
my_array_unique will return:
<?php
$foo_arr[0] ='aa';
$foo_arr[1] ='bb';
$foo_arr[2] ='cc';
$foo_arr[3] ='dd'
?>`
martin at lucas-smith dot co dot uk
27-Jan-2003 05:12
`To get a list of the duplicated values in an array, array_unique isn't much help. Instead, use array_filter in conjunction with a callback function, as below:
<?php
$checkKeysUniqueComparison = create_function('$value','if ($value > 1) return true;');
$result = array_keys (array_filter (array_count_values($array), $checkKeysUniqueComparison));
?>
These two lines therefore will create $result, an array of duplicated values in the array $array, once each. E.g. the array
$array = array ("a", "b", "a", "b", "x", "y", "z", "x");
gives the result
Array([0] => a [1] => b [2] => x)`
juggler at webworkerinfo dot de
10-Jan-2003 05:20
`in addition to bisqwit:
in some cases you can simply use serialize instead of recursivemakehash().
<?php
function array_unique2($input) {
$tmp = array();
foreach($input as $a => $b)
$tmp[$a] = serialize($b);
$newinput = array();
foreach(array_unique($tmp) as $a => $b)
$newinput[$a] = $input[$a];
return $newinput;
}
?>
Have fun
Juggler`
deigo at swirve dot NOSPAM dot com
23-Sep-2002 10:04
`Before I found the mysql distinct I had to make a nicer array from the keys/values that I got from array_unique so.
$groups=array_unique($groups);
$newgroup[0]=reset($groups);
for ($x=1;$x<sizeof($groups);$x++)
{
$newgroup[$x]=next($groups);
}`
php at hp-site dot dk
29-Aug-2002 11:15
`Try this:
array_flip(array_flip($array));
It gives the same result as the old array_unique()`
29-Aug-2002 02:39
`<?
$truc = array("l810u00","l810u00","l810q00");
$machin = array_unique($truc);
for($i=0;$i < count($machin) ; $i++){
print $machin[$i]."
";
}
?>
result :
l810u00
This is not strange: $machin (as returned by array unique), contains "l810u00" either in key[0] or key[1] but not both (the key depends on the ersion of PHP), and "l810q00" in key[2].
The returned array has TWO elements so count($machin)==2.
The returned array has a hole in it, and you're not displaying its full content. You could verify it by using this display loop instead:
foreach($machine as $key=>$value){
print '[' . $key . '] => ' . $value . '
";
}
result:
[0] => l810q00
[2] => l810u00
(the first line may display [1] instead of [0] for PHP 4.0.1p3, but you'll get the same order of values and two lines, as expected). When calling array_values() on the result, you're building a new array with the same values in the same order, but with renumbered keys (without holes in numeric keys).`
bisqwit at iki dot fi
25-May-2002 08:32
`The recursivemakehash() in my previous post contained a flaw. Adding md5() to "return $tab;" fixes it making it now possible to distinguish array(0=>'x') from 'F4DBDF218CDC1683' etc.`
bisqwit at iki dot fi
24-May-2002 09:36
`array_unique() doesn't return anything useful if your input is an
array containing arrays. This function overcomes the problem.
Any level of recursions is possible here. If the input is a plain
array, the result is compatible with array_unique() result.
<?php
function recursivemakehash($tab)
{
if(!is_array($tab))
return $tab;
$p = '';
foreach($tab as $a => $b)
$p .= sprintf('%08X%08X', crc32($a), crc32(recursivemakehash($b)));
return $p;
}
function array_unique2($input)
{
$dumdum = array();
foreach($input as $a => $b)
$dumdum[$a] = recursivemakehash($b);
$newinput = array();
foreach(array_unique($dumdum) as $a => $b)
$newinput[$a] = $input[$a];
return $newinput;
}
?>`
spunk at dasspunk dot NOSPAM dot com
14-Nov-2001 04:52
`I needed a way of retaining the original array's keys in the new, unique array. I came up with this. It works for my purposes but may need refinement.
function my_array_unique($somearray)
{
asort($somearray);
reset($somearray);
$currentarrayvar = current($somearray);
foreach ($somearray as $key=>$var)
{
if (next($somearray) != $currentarrayvar)
{
$uniquearray[$key] = $currentarrayvar;
$currentarrayvar = current($somearray);
}
}
reset($uniquearray);
return $uniquearray;
}`
ailanto at kafejo dot com
24-Aug-2001 09:04
`As in 4.0.3pl1, array_unique() in 4.0.5 returns the *last* key encountered for every value!`
eltehaem at N dot O dot S dot P dot A dot M dot free dot poltronic dot net
11-Aug-2001 07:26
`>array_unique() will keep the first key encountered
>for every value, and ignore all following keys.
This is true only in PHP 4.0.4pl1, i.e. the code below:
<?php
$temp = Array ('pl', 'pl', 'en', 'en', 'cz', 'de', 'en', 'pl');
print_r($temp);
print_r(array_unique($temp));
?>
Will produce this output:
Array
(
[0] => pl
[1] => pl
[2] => en
[3] => en
[4] => cz
[5] => de
[6] => en
[7] => pl
)
Array
(
[0] => pl
[2] => en
[4] => cz
[5] => de
)
And in PHP 4.0.3pl1 will produce this output:
Array
(
[0] => pl
[1] => pl
[2] => en
[3] => en
[4] => cz
[5] => de
[6] => en
[7] => pl
)
Array
(
[4] => cz
[5] => de
[6] => en
[7] => pl
)
This little function resolves the problem:
<?php
function my_array_unique(&$old){
$new = array();
foreach($old as $key => $value){
if(!in_array($value, $new)) $new[$key] = $value;
}
return $new;
}
?>`
az at top-webdesign dot de
10-Jul-2001 01:00
`Attention!
If you use array_unique be aware of data-types! (I spent hours of debugging because of that ...).
For example, if you've got an array containing a '3' as number and another '3' as string it won't be eliminated by array_unique.
An Example where this can happen, without really thinking about it:
I've got an article-list with product-numbers where the third and fourth digit is the code for the producer. So I read in the file an process it line by line and put each producer-code into an array:
------------------------------
<?php
$i=0;
while($line = fgets($csv, 10000) {
// splitting the line, product_no is the first part:
$data = explode(";", $line);
// putting the producer_code into an array:
$producer_id[$i] = trim(substr($data[0], 2, 2));
// make a special exception:
if(trim(substr($data[0], 2, 2)) == 40) {
$producer_id[$j] = '30';
}
// in the above line if you leave the 30 without the ''
// array_unique won't work!
$i++;
}
$producer_ids = array_values(array_unique($producer_id));
?>
-------------------------------
Result is to have all producer-ID's in an array without dupes.`
az at top-webdesign dot de
10-Jul-2001 12:38
`@lefeuvrenicolas
Use the above mentioned combination with "array_values" - then it works.
So do it like this:
--------------------
<?php
$truc = array("l810u00","l810u00","l810q00");
$machin = array_values(array_unique($truc));
for($i=0;$i < count($machin) ; $i++){
echo $machin[$i]."\n";
}
?>
--------------------
But it is strange anyway ...`
mads dot rebsdorf at am-vision dot dk
07-May-2001 05:55
`To unique an array in newer versions of php - i've found this snippet useful:
<?php
// $old[0] = 1
// $old[1] = 1
// $old[2] = 2
// $old[3] = 1
// $old[4] = 2
$new = array();
for($i=0;$i<count($old);++$i){
if(in_array($old[$i], $new) != "true"){
$new[] = $old[$i];
}
}
//$new now contains:
//
//$new[0] = 1
//$new[1] = 2
?>
/mads`
rein at velt dot net
21-Apr-2001 12:44
`Following code copies unique values from MyArray to TempArray.
Then copies non-empty elements from TempArray to UniqueArray.
Not the most elegant solution, but it works.
<?php
$TempArray = array_unique($MyArray);
while (list($index,$data)=each($TempArray)) {
if (isempty($data)) {
$UniqueArray[$index]=$data;
}
}
?>`
sneze at yahoo dot com
10-Feb-2001 09:47
`$users = array_unique($online_users);
foreach($users as $value){
echo $value;
}
saved my day`
burno at 33-24-36 dot com
10-Nov-2000 03:28
`Or just do a usort($myArray,"return -1"); after the usage of array_unique`
matthew_dean at hotmail dot com
26-Oct-2000 07:04
`Re: Useful comments from jllamas@bal.com.mx
If you are using a numerically indexed array and you want to make it unique but *with* consecutive indices, you can use array_values(array_unique($myArray));`
jllamas at bal dot com dot mx
25-Sep-2000 09:25
`It seems that array_unique creates an exact copy of the original array and then elimitates duplicate values. It does NOT change the "internal references" of the array. For example:
<?php
$test_alfa = array();
$test_alfa[0] = "aa";
$test_alfa[1] = "aa";
$test_alfa[2] = "aa";
$test_alfa[3] = "bb";
$test_alfa[4] = "aa";
$test_alfa[5] = "bb";
$test_alfa[6] = "cc";
$test_alfa[7] = "bb";
$test_beta= array_unique($test_alfa);
$numValues = count($test_beta);
for ($i = 0 ; $i <= 7 ; $i++)
echo("test_beta[$i] = $test_beta[$i] <br>");
echo ("Number of elements in test_beta = $numValues ");
?>
will give you the following output:
test_beta[0] =
test_beta[1] = aa
test_beta[2] =
test_beta[3] =
test_beta[4] =
test_beta[5] = bb
test_beta[6] = cc
test_beta[7] =
Number of elements in test_beta = 3
The point is that you won't get the output you'd expect if you think that the values of the non duplicate elements are located in the first three array locations.
$numValues = count($test_beta);
for ($i=0;$i<=$numValues; $i++)
echo("test_beta[$i] = $test_beta[$i] <br>");
echo ("Number of elements in test_beta = $numValues ");
will give you:
test_beta[0] =
test_beta[1] = aa
test_beta[2] =
Number of elements in test_beta = 3
Hope that saves u some debugging time!`
sterba at locksley-west dot com
05-Sep-2000 12:30
`Maybe this will come handy for PHP3 users:
<?php
for ($a = 0; $a < $arraylength; $a++){
if (($a > 0)&&($array[$a] <> $array[$a-1]))
$uniquearray[$a] = $array[$a];
$a++;
}
?>
You can even skip the $a>0 test, I believe... not bulletproof, but much shorter.`
moose at ucdavis dot edu
15-Aug-2000 02:08
`Here's a little function I wrote that's similar to array_unique, for PHP3 users. It actually removes duplicated elements, but only works for 1 dimensional arrays. It also doesn't return a value, it changes the input array:
<?php
function array_unique(&$thearray)
{sort($thearray);
reset($thearray);
$newarray = array();
$i = 0;
$element = current($thearray);
for ($n=0;$n<sizeof($thearray);$n++)
{if (next($thearray) != $element)
{$newarray[$i] = $element;
$element = current($thearray);
$i++;
}
}
$thearray = $newarray;
}
?>`
add a note
array_unshift array_uintersect

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