How do I count occurrence of duplicate items in array

Question

I would like to count the occurrence of each duplicate item in an array and end up with an array of only unique/non duplicate items with their respective occurrences.

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Answer 1

Count duplicate element of an array in PHP without using in-built function

$arraychars=array("or","red","yellow","green","red","yellow","yellow");
$arrCount=array();
        for($i=0;$i<$arrlength-1;$i++)
        {
          $key=$arraychars[$i];
          if($arrCount[$key]>=1)
            {
              $arrCount[$key]++;
            } else{
              $arrCount[$key]=1;
        }
        echo $arraychars[$i]."<br>";
     }
        echo "<pre>";
        print_r($arrCount);

Answer 2

You can do it using foreach loop.

          $arrayVal = array(1,2,3,1,2,3,1,2,3,4,4,5,6,4,5,6,88);
          $set_array = array();
          foreach ($array as $value) {
            $set_array[$value]++;
          }
           print_r($set_array);

Output :-

  Array( [1] => 3
             [2] => 3
             [3] => 3
             [4] => 3
             [5] => 2
             [6] => 2
             [88] => 1
            )

Answer 3

array_count_values, enjoy :-)

$array = array(12,43,66,21,56,43,43,78,78,100,43,43,43,21);
$vals = array_count_values($array);
echo 'No. of NON Duplicate Items: '.count($vals).'<br><br>';
print_r($vals);

Result:

No. of NON Duplicate Items: 7
Array
(
    [12] => 1
    [43] => 6
    [66] => 1
    [21] => 2
    [56] => 1
    [78] => 2
    [100] => 1
)

Answer 4

I actually wrote a function recently that would check for a substring within an array that will come in handy in this situation.

function strInArray($haystack, $needle) {
    $i = 0;
    foreach ($haystack as $value) {
        $result = stripos($value,$needle);
        if ($result !== FALSE) return TRUE;
        $i++;
    }
    return FALSE;
}

$array = array(12,43,66,21,56,43,43,78,78,100,43,43,43,21);

for ($i = 0; $i < count($array); $i++) {
    if (strInArray($array,$array[$i])) {
        unset($array[$i]);
    }
}
var_dump($array);

Answer 5

If you have a multi-dimensional array you can use on PHP 5.5+ this:

array_count_values(array_column($array, 'key'))

which returns e.g.

 [
   'keyA' => 4,
   'keyB' => 2,
 ]

Answer 6

You can also use it with text items array, u will get number of duplicates properly, but PHP shows

Warning: array_count_values(): Can only count STRING and INTEGER values!

$domains = 
array (
  0 => 'i1.wp.com',
  1 => 'i1.wp.com',
  2 => 'i2.wp.com',
  3 => 'i0.wp.com',
  4 => 'i2.wp.com',
  5 => 'i2.wp.com',
  6 => 'i0.wp.com',
  7 => 'i2.wp.com',
  8 => 'i0.wp.com',
  9 => 'i0.wp.com' );

$tmp = array_count_values($domains);
print_r ($tmp);

    array (
      'i1.wp.com' => 2730,
      'i2.wp.com' => 2861,
      'i0.wp.com' => 2807
    )