How to get unique value in multidimensional array

Question

I have done a lot of looking around on the overflow, and on google, but none of the results works for my specific case.

I have a placeholder array called $holder, values as follows:

    Array ( 
    [0] => Array ( 
        [id] => 1 
        [pid] => 121 
        [uuid] => 1  
        )
    [1] => Array ( 
        [id] => 2 
        [pid] => 13
        [uuid] => 1
        )
    [2] => Array ( 
        [id] => 5 
        [pid] => 121 
        [uuid] => 1
        )
    )

I am trying to pull out distinct/unique values from this multidimensional array. The end result I would like is either a variable containing (13,121), or (preferrably) an array as follows: Array( [0] => 13 [1] => 121 )

Again I've tried serializing and such, but don't quite understand how that works when operating with a single key in each array.

I tried to be as clear as possible. I hope it makes sense...

possible duplicate [PHP remove duplicate values from multidimensional array](http://stackoverflow.com/questions/3598298/php-remove-duplicate-values-from-multidimensional-array) — arun, May 02 '12 at 06:09

score 74 · Accepted Answer · answered May 02 '12 at 06:06

74

Seems pretty simple: extract all pid values into their own array, run it through array_unique:

$uniquePids = array_unique(array_map(function ($i) { return $i['pid']; }, $holder));

The same thing in longhand:

$pids = array();
foreach ($holder as $h) {
    $pids[] = $h['pid'];
}
$uniquePids = array_unique($pids);

answered May 02 '12 at 06:06

deceze

510,633
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743
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2

I wonder why this doesn't work `array_unique(array_map(function ($i) { return $i[$id]; }, $holder));` Is there a way to use variable instead of predefined key name? – Ilia Ross Aug 30 '14 at 13:44
@deceze Ah, alright, it's inside of anonymous function. Thanks! – Ilia Ross Aug 30 '14 at 15:19
This works but is inefficient. Why add a bunch of elements and remove them immediately? Just loop over the array and filter one by one! I'm adding my own answer. – Jorge Orpinel Pérez Feb 11 '15 at 23:37
1

@Jorge Yes, this could be made more efficient by looping over the array once, putting all its elements into a new array *as keys*, then extracting just the keys. However, there's a tradeoff between readability, maintainability and performance, and I think this solution strikes a decent balance which will be just fine for average sized arrays. – deceze Feb 11 '15 at 23:48

score 42 · Answer 2 · answered May 25 '15 at 14:48

42

In php >= 5.5 you can use array_column:

array_unique(array_column($holder, 'pid'));

answered May 25 '15 at 14:48

Dondi Imperial

516
4
2

score 4 · Answer 3 · answered May 02 '12 at 06:08

4

try this

foreach($arr as $key => $val) {
    $new_arr[] = $val['pid'];
}
$uniq_arr = array_unique($new_arr);

answered May 02 '12 at 06:08

Nauphal

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score 4 · Answer 4 · answered May 02 '12 at 06:08

4

Just iterate over it and apply an array_unique on the result:

foreach($holder as $yourValues){
    $pids[] = $yourValues['pid'];
}
$yourUniquePids = array_unique($pids);

answered May 02 '12 at 06:08

konsolenfreddy

9,551
1
25
36

score 4 · Answer 5 · answered Feb 11 '15 at 23:43

4

Assuming your array is called $holder:

$unique = array();
foreach( $holder as $h )
    if( ! in_array($h, $unique ) )
        $unique[] = $h;

is a slightly more efficient way than via array_unique, I believe. May be the same.

answered Feb 11 '15 at 23:43

Jorge Orpinel Pérez

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`in_array` is essentially looping over the array again and again, so you've got two nested loops. That's inefficient in its own way. – deceze Feb 11 '15 at 23:45

score 1 · Answer 6 · answered Feb 03 '20 at 13:25

1

$uniquearray = [];
    for($i=0;$i<count($assocarray);$i++){
        if(!in_array($assocarray[$i]['KEY'],$uniquearray)){
            $uniquearray[$i]= $assocarray[$i]['KEY'];
        }
}

answered Feb 03 '20 at 13:25

Anti logic

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6

Can you provide a brief explanation in addition to your code? – Sam Chats Feb 03 '20 at 13:36

score 0 · Answer 7 · answered May 02 '12 at 06:30

Hi Please try code given below for get unique values and then sort that values

<?php

$sort_arr = unique_sort($holder, 'pid');
echo "<pre>";
print_r($sort_arr);
echo"</pre>";

/*function for get unique value then sort them*/

function unique_sort($arrs, $id) {
    $unique_arr = array();
    foreach ($arrs AS $arr) {

        if (!in_array($arr[$id], $unique_arr)) {
            $unique_arr[] = $arr[$id];
        }
    }
    sort($unique_arr);
    return $unique_arr;
}

thanks

score -1 · Answer 8 · answered Dec 30 '16 at 09:11

fo my situation i use this method

//get some data from db to array
while ($row = mysqli_fetch_assoc($query)){
   $data[] = $row;
}

//display unique value
echo "<table>";
$uniq = array();
foreach ($data as $row) {
    if(!in_array($row['path'], $uniq)) {
        $uniq[] = $row['path'];
        echo "<tr>";
        echo "<td>";
        echo $row['path'];
        echo "</td>";
        echo "<td>";
        echo $row['relationship_id'];
        echo "</td>";
        echo "</tr>";
    }
}
echo "</table>";

I don't see how that respond to the question: wich is getting unique value in a multidimensional array — goto, Dec 30 '16 at 09:42

How to get unique value in multidimensional array

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