How to get rid of duplicate values from multidimensional array

Question

I want to remove duplicate values from multi-dim array, I tried all the possible solutions which is already described but for me, is not working, can anyone please correct it? Here's my Array:

Array ( 
  [0] => Array ( 
         [0] => element_10 
         [1] => block_1 
         [2] => element_4 
         [3] => element_1 
         [4] => element_3 
               ) 
[1] => Array ( 
        [0] => block_1 
        [1] => block_2 
        [2] => element_8 
        [3] => element_10 
        [4] => element_12 
        [5] => element_14 
        [6] => element_4 
        [7] => element_2 
        [8] => element_3 
        [9] => element_9 
        [10] => element_13 
        [11] => element_7 
          ) 
)

Where I want the array in this format:

Array ( 
  [0] => Array ( 
         [0] => element_10 
         [1] => block_1 
         [2] => element_4 
         [3] => element_1 
         [4] => element_3 
               ) 
[1] => Array ( 
        [1] => block_2 
        [2] => element_8 
        [4] => element_12 
        [5] => element_14 
        [7] => element_2 
        [9] => element_9 
        [10] => element_13 
        [11] => element_7 
          ) 
)

Ican setup the key indexes later.

I tried:

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);
}

No Luck, then I tried:

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

Still same array returning.

I tried this method too:

function super_unique($array)
{
  $result = array_map("unserialize", array_unique(array_map("serialize", $array)));

  foreach ($result as $key => $value)
  {
    if ( is_array($value) )
    {
      $result[$key] = self::super_unique($value);
    }
  }
  return $result;
}

Please help me, I know it's pretty simple I don't know where I'm losing?

Thanks,

user229044 · Accepted Answer · 2014-02-13 15:51:19Z

2

You need to iterate over your list of input arrays. For each value in that array, you need to see if you've previously encountered it, so you'll have to keep a super-set of all values across all arrays, which you gradually append to. If a value already exists in the super-set array, you can remove it, otherwise you can append it.

function multi_unique($arrays) {
  $all_values = array();

  foreach ($arrays as &$array) {
    foreach ($array as $index => $value) {
      if (in_array($value, $all_values)) {
        // We've seen this value previously
        unset($array[$index]);
      } else {
        // First time we've seen this value, let it pass but record it
        $all_values[] = $value;
      }
    }
  }
  return $arrays;
}


$values = array (
  array ( 'element_10', 'block_1', 'element_4', 'element_1', 'element_3',) ,
  array ( 'block_1', 'block_2', 'element_8', 'element_10', 'element_12', 'element_14', 'element_4', 'element_2', 'element_3', 'element_9', 'element_13', 'element_7',)
);

var_dump(multi_unique($values));

Output:

array(2) {
  [0]=>
  array(5) {
    [0]=>
    string(10) "element_10"
    [1]=>
    string(7) "block_1"
    [2]=>
    string(9) "element_4"
    [3]=>
    string(9) "element_1"
    [4]=>
    string(9) "element_3"
  }
  [1]=>
  array(8) {
    [1]=>
    string(7) "block_2"
    [2]=>
    string(9) "element_8"
    [4]=>
    string(10) "element_12"
    [5]=>
    string(10) "element_14"
    [7]=>
    string(9) "element_2"
    [9]=>
    string(9) "element_9"
    [10]=>
    string(10) "element_13"
    [11]=>
    string(9) "element_7"
  }
}

edited Feb 13, 2014 at 15:51

answered Feb 13, 2014 at 15:44

user229044♦

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4 Comments

Nadeem Over a year ago

there's a typo for $index, $value to $index => $value but the thing is I don't want to merge arrays I want to keep the [0] = [0] => element_10 [1] => block_1 [2] => element_8 .... [1] = [0] => element_1 [1] => block_2 [2] => element_10 ....

Nadeem Over a year ago

Perfect you're life savior @meagar :)

php-dev Over a year ago

Think performace! Look at @moonwave99 answer below.

user229044 Over a year ago

@user3165879 Think "learning to program". My answer was meant to educate on why the posted attempts were wrong, not to be the most performant solution. I took it for granted that the goal was to operate on a list of two or more arrays; if the goal really is to just diff two arrays, then yes, array_diff is the way to go.

moonwave99 · Accepted Answer · 2014-02-13 15:47:23Z

1

If you just want to remove duplicates from the second entry of your array, use array_diff():

$array[1] = array_diff($array[1], $array[0]);

Iterate if you want to apply it to an arbitrary length.

answered Feb 13, 2014 at 15:47

moonwave99

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1 Comment

php-dev Over a year ago

Best solution!! Better that looping over array so much nested loops. But it only needs to be adapted to more than 2 elements array. +1 anyway

php-dev · Accepted Answer · 2014-02-13 15:57:02Z

0

Why are you using the serialize function.

Use array_diff instead.

A simple would be.

$orginal = array(array(values), array(values), ...);

$copy = $original;

foreach($original as $k => $subArray) {
    $tmpCopy = $copy;
    unset($tmpCopy[$k]);
    unshift($tmpCopy, $subArray);
    $tmpCopy = array_values($tmpCopy);
    $original[$k] = call_user_func_array('array_diff', $tmpCopy);
}

This works for a two dimensions array.

Hope it helps.

answered Feb 13, 2014 at 15:57

php-dev

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