php multi-dimensional array remove duplicate

Question

Not sure if this question is a duplicate in need of removal, but I couldn't find the answer elsewhere so I'll have a go at asking.

I've got a 2d array that looks as follows:

Array
(
[0] => Array
    (
        [0] => dave
        [1] => jones
        [2] => c@b.c
    )

[1] => Array
    (
        [0] => john
        [1] => jones
        [2] => a@b.c

    )

[2] => Array
    (
        [0] => bruce
        [1] => finkle
        [2] => c@b.c
    )
)

I'd like to remove those with duplicate emails. So in the above example I'd like to just remove either [][0] or [][2]. I'm not worried about checking against names or anything like that, I just need the sub arrays to be deduplicated based on a single value.

At the moment I have something like this

  if(is_array($array) && count($array)>0){
  foreach ($array as $subarray) {
    $duplicateEmail[$subarray[2]] = isset($duplicateEmail[$subarray[2]]);
    unset($duplicateEmail[$subarray[2]]);
   }
  }

but it just ain't right. Any help appreciated.

Answer 1

A quick solution which uses the uniqueness of array indexes:

$newArr = array();
foreach ($array as $val) {
    $newArr[$val[2]] = $val;    
}
$array = array_values($newArr);

Notice 1: As visible from above, the last match for an email address is used instead of the first. This can be changed by replacing the second line with

foreach (array_reverse($array) as $val) {

Notice 2: The indexes in the resulting array are somewhat mixed up. But I guess this doesn't matter...

Answer 2

Much Simpler Solution.

$unique = array_map('unserialize', array_unique(array_map('serialize', $array)));

echo "<pre>";
print_r($unique);

Answer 3

The user comments for array_unique() have a few solutions to this. For example

    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);
    }

from http://uk.php.net/manual/en/function.array-unique.php#57202.

Answer 4

$array = array(
    array('dave','jones','c@b.c'),
    array('dave','jones','a@c.d'),
    array('dave','jones','c@b.c'),
    array('dave','jones','e@v.d'),
    array('dave','jones','a@c.d')   
);

$copy = $array; // create copy to delete dups from
$usedEmails = array(); // used emails

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

    if ( in_array( $array[$i][2], $usedEmails ) ) {
        unset($copy[$i]);
    }
    else {
        $usedEmails[] = $array[$i][2];
    }

}

print_r($copy);

Answer 5

User SORT_REGULAR as second parameter.

$uniqueArray = array_unique($array, SORT_REGULAR);

Answer 6

My proposition:

protected function arrayUnique($array, $preserveKeys = false)
{
    $uniqueArray = array();
    $hashes = array();

    foreach ($array as $key => $value) {
        if (true === is_array($value)) {
            $uniqueArray[$key] = $this->arrayUnique($value, $preserveKeys);

        } else {
            $hash = md5($value);

            if (false === isset($hashes[$hash])) {
                if ($preserveKeys) {
                    $uniqueArray[$key] = $value;
                } else {
                    $uniqueArray[] = $value;
                }

                $hashes[$hash] = $hash;
            }
        }
    }

    return $uniqueArray;
}