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

    $input = [1,2,1,3,2,4,10];
    //if give string
    //$input = "hello hello how are you how hello";
    //$array = explode(' ',$input);
    $count_val = [];
    foreach($array as $val){
      $count_val[$val]++;
    }
    print_r($count_val);
//output ( [1] => 2 [2] => 2 [3] => 1 [4] => 1 [10] => 1 )

Answer 2

There is a magical function PHP is offering to you it called in_array().

Using parts of your code we will modify the loop as follows:

<?php
$array = array(12,43,66,21,56,43,43,78,78,100,43,43,43,21);
$arr2 = array();
$counter = 0;
for($arr = 0; $arr < count($array); $arr++){
    if (in_array($array[$arr], $arr2)) {
        ++$counter;
        continue;
    }
    else{
        $arr2[] = $array[$arr];
    }
}
echo 'number of duplicates: '.$counter;
print_r($arr2);
?>

The above code snippet will return the number total number of repeated items i.e. form the sample array 43 is repeated 5 times, 78 is repeated 1 time and 21 is repeated 1 time, then it returns an array without repeat.

Answer 3

$search_string = 4;
$original_array = [1,2,1,3,2,4,4,4,4,4,10];
$step1 = implode(",", $original_array); // convert original_array to string
$step2 = explode($search_string, $step1); // break step1 string into a new array using the search string as delimiter
$result = count($step2)-1; // count the number of elements in the resulting array, minus the first empty element
print_r($result); // result is 5

Answer 4

if you want to try without 'array_count_values' you can do with a smart way here

<?php
$input= array(12,43,66,21,56,43,43,78,78,100,43,43,43,21);

$count_values = array();
foreach ($input as $a) {

     @$count_values[$a]++;

}
echo 'Duplicates count: '.count($count_values);
print_r($count_values);
?>

Answer 5

I came here from google looking for a way to count the occurence of duplicate items in an array. Here is the way to do it simply:

$colors = array("red", "green", "blue", "red", "yellow", "blue");
$unique_colors = array_unique($colors);
// $unique colors : array("red", "green", "blue", "yellow")
$duplicates = count($colors) - count($unique_colors);
// $duplicates = 6 - 4 = 2
if( $duplicates == 0 ){
 echo "There are no duplicates";
}
echo "No. of Duplicates are :" . $duplicates;

// Output: No. of Duplicates are: 2

How array_unique() works?

It elements all the duplicates. ex: Lets say we have an array as follows -

$cars = array( [0]=>"lambo", [1]=>"ferrari", [2]=>"Lotus", [3]=>"ferrari", [4]=>"Bugatti");

When you do $cars = array_unique($cars); cars will have only following elements. $cars = array( [0]=>"lambo", [1]=>"ferrari", [2]=>"Lotus", [4]=>"Bugatti");

To read more: https://www.w3schools.com/php/func_array_unique.asp

Hope it is helpful to those who are coming here from google looking for a way to count duplicate values in array.

Answer 6

this code will return duplicate value in same array

$array = array(12,43,66,21,56,43,43,78,78,100,43,43,43,21);
foreach($arr as $key=>$item){
  if(array_count_values($arr)[$item] > 1){
     echo "Found Matched value : ".$item." <br />";
  }
}