Remove duplicate items from an array

Question

I use the line of code below to loop through a table in my database:

$items_thread = $connection -> fetch_all($sql);

And if I print the array out:

print_r($items_thread);

I will get this:

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => info@xx.com
        )

    [1] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => info@xx.com
        )

    [2] => Array
        (
            [RecipientID] => 1
            [RecipientScreenname] => Lau T
            [RecipientFirstname] => TK
            [RecipientEmail] => lau@xx.co.uk
        )

)

But I want to get rid of the duplicate items in the array, so I use array_unique

print_r(array_unique($items_thread));

I get the weird result below which is not quite I am looking for:

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => info@xx.com
        )

)

Ideally, I think it should return this:

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => info@xx.com
        )

    [1] => Array
        (
            [RecipientID] => 1
            [RecipientScreenname] => Lau T
            [RecipientFirstname] => TK
            [RecipientEmail] => lau@xx.co.uk
        )

)

What shall I do to get it right? Have I used the wrong PHP syntax/default function?

`array_unique()` is reducing everything to a single array because it's comparing your inner arrays as strings, all of which evaluate to `Array`. So every array is considered the same. Additionally, from the [manual](http://www.php.net/manual/en/function.array-unique.php): "Note that `array_unique()` is not intended to work on multi dimensional arrays." — BoltClock, Feb 18 '11 at 00:30
thank you for your suggestion - SELECT DISTINCT RecipientID. It does not return the result I need, even though I can get the unique value from it... you can have a look on the post i made earlier on here - http://stackoverflow.com/questions/5032645/mysql-php-send-emails-to-the-members-who-fall-into-last-3-active-threads thanks. — Run, Feb 18 '11 at 00:46

score 68 · Accepted Answer · edited May 23 '17 at 12:10

68

The array_unique function will do this for you. You just needed to add the SORT_REGULAR flag:

$items_thread = array_unique($items_thread, SORT_REGULAR);

However, as bren suggests, you should do this in SQL if possible.

edited May 23 '17 at 12:10

Community

1
1

answered Feb 18 '11 at 00:29

I have been looking for this for about half a day! – Oguzhan Aug 12 '15 at 12:14

score 7 · Answer 2 · answered Feb 18 '11 at 00:28

7

You'd be much better off filtering out the duplicates in the SQL query. add a constraint which fetches a UNIQUE recipientID

answered Feb 18 '11 at 00:28

bren

106
3

3

`SELECT DISTINCT RecipientID ...` – BoltClock Feb 18 '11 at 00:31
@BoltClock thanks... Could you explain why this way is better than `array_unique()` ? – CJ Ramki Apr 29 '14 at 01:50
1

@CJ Ramki: You waste less resources by only selecting the rows that you need and not grabbing everything from the database and throwing away the ones that you don't need. – BoltClock Apr 29 '14 at 01:52
So, if I have array like [this](http://pastie.org/9121494), `array_unique()` will compare the string `Array`and `Array` and produce the result? – CJ Ramki Apr 29 '14 at 02:05

score 4 · Answer 3 · edited Jul 03 '12 at 07:16

To remove duplicate values then we can use array_unique() function. The functionality of it is to accept an array and returns another array without duplicate values.

General description of array_unique() is given below:

General Format = array array_unique(array $array [, int $sort_flags=sort_string] )
Parameters     = array: Input array ->sort_flags:
    The second optional parameter is used to compare items as follows
         1. SORT_REGULAR - Normal
         2. SORT_NUMERIC - Numerically
         3. SORT_STRING - As
         4. string  SORT_LOCALE_STRING - As string, based on the current locale.
Return Value   = Another array without duplicate values

Example 1:

<?php
$array=array('cricket'=>11,'football'=>11,'chess'=>2);
echo"<br/><b>Initially the values of \$array is:</b><br/>";
var_dump($array);
echo"<br/><b>After removing the duplicates:</b><br/>";
print_r(array_unique($array));
?>

Output:

Initially the values of $array is:
array(3) {
  ["cricket"] => int(11)
  ["football"] => int(11)
  ["chess"] => int(2)
}

After removing the duplicates:
Array
(
    [cricket] => 11
    [chess] => 2
)

score 1 · Answer 4 · edited Sep 29 '16 at 13:30

You can use this code and I hope it will help you. It's completely working:

$array = array(1,1,2,3,4,4,4,5);
$temp=array();

for($i=0; $i<=count($array); $i++)
 {

    if($array[$i] != '')
    {
        for($j=$i+1; $j<=count($array); $j++ )
        {
            if($array[$i]==$array[$j])
            {
                $array[$j] = '';
            }
            else
            {
                $temp[$array[$i]]=$array[$i];
            }

         }

    }
}

print_r($temp);

score 1 · Answer 5 · edited May 23 '17 at 11:47

1

Try this:

$data = array_map('unserialize', array_unique(array_map('serialize', $data)));

Outputs the following:

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => info@xx.com
        )

    [2] => Array
        (
            [RecipientID] => 1
            [RecipientScreenname] => Lau T
            [RecipientFirstname] => TK
            [RecipientEmail] => lau@xx.co.uk
        )
)

But I also think you should implement this in your database. Also, check my other answer and solutions.

edited May 23 '17 at 11:47

Community

1
1

answered Feb 18 '11 at 01:00

Alix Axel

151,645
95
393
500

thank you for this! what about $items_thread = array_unique($items_thread, SORT_REGULAR); which returns the same result as your code? – Run Feb 18 '11 at 01:07
@lauthiamkok: I've never done that, does it really return the same output? If yes, great! – Alix Axel Feb 18 '11 at 01:53
@lauthiamkok: I've read the manual and that flag seems to deliver the correct results, however bare in mind that it's only available in PHP >= 5.2.9. – Alix Axel Feb 18 '11 at 01:55
thanks. I'm on php 5.3.x and my live will be on 5.3.x too so I think I am safe! thank you very much! – Run Feb 18 '11 at 02:47

score 0 · Answer 6 · answered May 02 '15 at 15:23

0

~~$unique = array_keys(array_flip($array));~~

It's is faster, plus it reset the array key index.

source: http://php.net/manual/en/function.array-unique.php#89519

This only for a simple array.

answered May 02 '15 at 15:23

H Aßdøµ

2,925
4
26
37

Raju Dudhrejiya · Answer 7 · 2015-07-10T06:52:00.173

Please check below code, I hope this is help full for you.

$resultArray = uniqueAssocArray($actualArray, 'RecipientID');

function uniqueAssocArray($array, $uniqueKey) {
if (!is_array($array)) {
    return array();
}
$uniqueKeys = array();
foreach ($array as $key => $item) {
    $groupBy=$item[$uniqueKey];
    if (isset( $uniqueKeys[$groupBy]))
    {
        //compare $item with $uniqueKeys[$groupBy] and decide if you 
        //want to use the new item
        $replace= false; 
    }
    else
    {
        $replace=true;
    }
    if ($replace) $uniqueKeys[$groupBy] = $item;   
}
return $uniqueKeys;

}

score 0 · Answer 8 · answered Jul 28 '15 at 11:28

$res1       = mysql_query("SELECT * FROM `luggage` where r_bus_no='".$tour_id."' and `date1`='$date' AND `login_id`='".$_SESSION['login_id']."'");
}
/// create a array to store value
$city_arr   = array();
if(mysql_num_rows($res1)>0)
{
    while($row1 = mysql_fetch_array($res1))
    {

/// insert the value in array use the array_push function
            array_push($city_arr,$row1['r_to']);
    }

//// remove the duplicate entry in array use the array_unique function
    $a          = array_unique($city_arr);
    echo "<option value='' selected='selected'> -- Select City ---</option>";
    foreach($a as $b)
    {
    ?>
    <option value="<?php echo $b ;?>"><?php echo city($b); ?></option>
    <?php       
    }
}

score 0 · Answer 9 · answered Feb 18 '11 at 00:30

0

You can use the regular php arrays to achieve this.

$newArray = array();
foreach ($origArray as $user)
{
   $newArray[$user['RecipientID']] = $user;
}

answered Feb 18 '11 at 00:30

Byron Whitlock

52,691
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123
168

Remove duplicate items from an array

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