How can i remove duplicate values from a multi dimensional array in php?

How can I remove duplicate values from a multi-dimensional array in PHP?

Example array:

Array
(
    [0] => Array
    (
        [0] => abc
        [1] => def
    )

    [1] => Array
    (
        [0] => ghi
        [1] => jkl
    )

    [2] => Array
    (
        [0] => mno
        [1] => pql
    )

    [3] => Array
    (
        [0] => abc
        [1] => def
    )

    [4] => Array
    (
        [0] => ghi
        [1] => jkl
    )

    [5] => Array
    (
        [0] => mno
        [1] => pql
    )

)

asked Nov 21, 2008 at 2:50

1

Here is another way. No intermediate variables are saved.

We used this to de-duplicate results from a variety of overlapping queries.

$input = array_map("unserialize", array_unique(array_map("serialize", $input)));

jeromegamez

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answered Jun 3, 2009 at 18:12

daveilersdaveilers

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13

Since 5.2.9 you can use array_unique() if you use the SORT_REGULAR flag like so:

array_unique($array, SORT_REGULAR);

This makes the function compare elements for equality as if $a == $b were being used, which is perfect for your case.

Output

Array
(
    [0] => Array
        (
            [0] => abc
            [1] => def
        )

    [1] => Array
        (
            [0] => ghi
            [1] => jkl
        )

    [2] => Array
        (
            [0] => mno
            [1] => pql
        )

)

Keep in mind, though, that the documentation states:

array_unique() is not intended to work on multi dimensional arrays.

answered Aug 22, 2013 at 7:01

Ja͢ckJa͢ck

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14

I had a similar problem but I found a 100% working solution for it.

";
print_r($arr);
echo "unique*********************
";
print_r(super_unique($arr,'titel'));

?>

Martin

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answered May 9, 2012 at 10:48

3

Another way. Will preserve keys as well.

function array_unique_multidimensional($input)
{
    $serialized = array_map('serialize', $input);
    $unique = array_unique($serialized);
    return array_intersect_key($input, $unique);
}

answered Nov 21, 2008 at 14:36

OISOIS

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1

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => john
        )

    [1] => Array
        (
            [id] => 2
            [name] => smith
        )

    [2] => Array
        (
            [id] => 3
            [name] => john
        )

    [3] => Array
        (
            [id] => 4
            [name] => robert
        )

)

$temp = array_unique(array_column($array, 'name'));
$unique_arr = array_intersect_key($array, $temp);

This will remove the duplicate names from array. unique by key

answered Feb 23, 2018 at 6:34

Mahak ChoudharyMahak Choudhary

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2

If "remove duplicates" means "remove duplicates, but let one there", a solution might be to apply the array_unique(...) on the "identifier column" first and then to remove in the original array all the keys, that have been removed from the column array:

$array = [
    [
        'id' => '123',
        'foo' => 'aaa',
        'bar' => 'bbb'
    ],
    [
        'id' => '123',
        'foo' => 'ccc',
        'bar' => 'ddd'
    ],
    [
        'id' => '567',
        'foo' => 'eee',
        'bar' => 'fff'
    ]
];

$ids = array_column($array, 'id');
$ids = array_unique($ids);
$array = array_filter($array, function ($key, $value) use ($ids) {
    return in_array($value, array_keys($ids));
}, ARRAY_FILTER_USE_BOTH);

The result is:

Array
(
    [0] => Array
        (
            [id] => 123
            [foo] => aaa
            [bar] => bbb
        )

    [2] => Array
        (
            [id] => 567
            [foo] => eee
            [bar] => fff
        )

)

answered May 20, 2016 at 22:14

automatixautomatix

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1

The user comments on the array_unique() documentation have many solutions to this. Here is one of them:

kenrbnsn at rbnsn dot com
27-Sep-2005 12:09

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.

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);
}

This is from http://ca3.php.net/manual/en/function.array-unique.php#57202.

Manoj Sharma

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answered Nov 21, 2008 at 3:07

Paige RutenPaige Ruten

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0

if you need to eliminate duplicates on specific keys, such as a mysqli id, here's a simple funciton

function search_array_compact($data,$key){
    $compact = [];
    foreach($data as $row){
        if(!in_array($row[$key],$compact)){
            $compact[] = $row;
        }
    }
    return $compact;
}

Bonus Points You can pass an array of keys and add an outer foreach, but it will be 2x slower per additional key.

answered Nov 8, 2014 at 7:17

r3wtr3wt

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2

if you have an array like this:

(users is the name of the array)

Array=>
 [0] => (array)
   'user' => 'john'
   'age' => '23'
 [1] => (array)
  'user' => 'jane'
  'age' => '20'
 [2]=> (array)
  'user' => 'john'
  'age' => '23'

and you want to delete duplicates...then:

$serialized = array();
for ($i=0; $i < sizeof($users); $i++) { 
  $test = in_array($users['user'], $serialized);
    if ($test == false) {
      $serialized[] = $users['user'];
    }
 }

can be a solution :P

answered Aug 7, 2015 at 18:45

LimonLimon

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1

Lots of person asked me how to make Unique multidimensional array. I have taken reference from your comment and it helps me.

First of All, Thanks to @jeromegamez @daveilers for your solution. But every time i gave the answer, they asked me how this 'serialize' and 'unserialize' works. That's why i want to share the reason of this with you so that it will help more people to understand the concept behind this.

I am explaining why we use 'serialize' and 'unserialize' in steps :

Step 1: Convert the multidimensional array to one-dimensional array

To convert the multidimensional array to a one-dimensional array, first generate byte stream representation of all the elements (including nested arrays) inside the array. serialize() function can generate byte stream representation of a value. To generate byte stream representation of all the elements, call serialize() function inside array_map() function as a callback function. The result will be a one dimensional array no matter how many levels the multidimensional array has.

Step 2: Make the values unique

To make this one dimensional array unique, use array_unique() function.

Step 3: Revert it to the multidimensional array

Though the array is now unique, the values looks like byte stream representation. To revert it back to the multidimensional array, use unserialize() function.

$input = array_map("unserialize", array_unique(array_map("serialize", $input)));

Thanks again for all this.

answered Sep 1, 2016 at 11:29

ManishManish

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A very easy and logical way to Unique a multi dimension array is as follows,

If you have array like this:

Array
(
    [Key1] => Array
        (
            [0] => Value1
            [1] => Value2
            [2] => Value1
            [3] => Value3
            [4] => Value1
        )
    [Key2] => Array
        (
            [0] => Value1
            [1] => Value2
            [2] => Value1
            [3] => Value3
            [4] => Value4
        )
)

use foreach to solve this:

foreach($array as $k=>$v){
    $unique=array_unique($v);
    $array[$k]=$unique;
}

it will give you following result:

Array
(
    [Key1] => Array
        (
            [0] => Value1
            [1] => Value2
            [3] => Value3
        )
    [Key2] => Array
        (
            [0] => Value1
            [1] => Value2
            [3] => Value3
            [4] => Value4
        )
)

and if you want to rearrange the order of the keys,

foreach($array as $k=>$v){
    $unique= array_values(array_unique($v));
    $array[$k]=$unique;
}

This operation will give you arranged key values like this:

Array
(
    [Key1] => Array
        (
            [0] => Value1
            [1] => Value2
            [2] => Value3
        )
    [Key2] => Array
        (
            [0] => Value1
            [1] => Value2
            [2] => Value3
            [3] => Value4
        )
)

I hope this will clear everything.

answered Jan 19, 2018 at 13:22

1

An easy to read solution, probably not the most efficient:

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;

} 

graham.reeds

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answered Jun 19, 2009 at 19:44

pixelinepixeline

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As people are saying array_unique() is very slow, here is a snippet I use for one level multidimensional array.

$serialized_array = array_map("serialize", $input);

foreach ($serialized_array as $key => $val) {
     $result[$val] = true;
}

$output = array_map("unserialize", (array_keys($result)));

Reference first user contributed note of array_unique() function page in php.net

answered Apr 18, 2015 at 19:01

AnujAnuj

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0

An alternative to serialize and unique

$test = [
    ['abc','def'],
    ['ghi','jkl'],
    ['mno','pql'],
    ['abc','def'],
    ['ghi','jkl'],
    ['mno','pql'],
];

$result = array_reduce(
    $test,
    function($carry,$item){
        if(!in_array($item,$carry)) {
            array_push($carry,$item);
        }
        return $carry;
    },
    []
);

var_dump($result);

/*
 php unique.php
array(3) {
    [0] =>
        array(2) {
            [0] =>
                string(3) "abc"
            [1] =>
                string(3) "def"
        }
    [1] =>
        array(2) {
            [0] =>
                string(3) "ghi"
            [1] =>
                string(3) "jkl"
        }
    [2] =>
        array(2) {
              [0] =>
                  string(3) "mno"
              [1] =>
                  string(3) "pql"
        }
}

*/

answered Nov 6, 2014 at 23:04

1

I've given this problem a lot of thought and have determined that the optimal solution should follow two rules.

1. For scalability, modify the array in place; no copying to a new array
2. For performance, each comparison should be made only once

With that in mind and given all of PHP's quirks, below is the solution I came up with. Unlike some of the other answers, it has the ability to remove elements based on whatever key(s) you want. The input array is expected to be numeric keys.

$count_array = count($input);
for ($i = 0; $i < $count_array; $i++) {
    if (isset($input[$i])) {
        for ($j = $i+1; $j < $count_array; $j++) {
            if (isset($input[$j])) {
                //this is where you do your comparison for dupes
                if ($input[$i]['checksum'] == $input[$j]['checksum']) {
                    unset($input[$j]);
                }
            }
        }
    }
}

The only drawback is that the keys are not in order when the iteration completes. This isn't a problem if you're subsequently using only foreach loops, but if you need to use a for loop, you can put $input = array_values($input); after the above to renumber the keys.

answered Mar 5, 2015 at 14:04

SnakeSnake

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1

try this solution for (n) Dimensional array with non-restricted length
for example this array

$arr= [
0 => [0=>"a" , 1=>"b" ,  2=>"c" ] ,
1 => [0=>"x" , 1=>"b" , 2=>"a", 3=>"p"],
2=>   [
       [ 
          0=>"y" ,
          1=>"b" ,
          2=> [0=>"x" , 1=>"m" , 2=>"a"]
       ],
       1=>"z" ,
       2=>"v"
       ]
     ];

This would be the solution

$ar2=[];
$ar3=[];
function test($arr){
    
    global $ar2,$ar3;
    if(is_array($arr)){
       return array_map("test",$arr);
    }
    if(!isset($ar2[$arr])){
        $ar2[$arr]=1;
        $ar3[]=$arr;
    }
}
array_map("test",$arr);
print_r($ar3);

answered May 26 at 13:44

Based on the Answer marked as correct, adding my answer. Small code added just to reset the indices-

$input = array_values(array_map("unserialize", array_unique(array_map("serialize", $inputArray))));

answered Feb 14, 2020 at 11:01

GaganGagan

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1

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