Find Duplicate Value in Multi-Dimensional Array

PHP: Check for duplicate values in a multidimensional array

This will remove duplicate items from your array using array_unique():

$new_arr = array_unique($arr, SORT_REGULAR);

How to detect duplicate values in multidimensional associative array?

Simple solution is:

<?php

$data = [
  [
    'name' => 'name 1',
    'phone' => '12341234',
    'email' => 'test@web.com'
  ],
  [
    'name' => 'name 2',
    'phone' => '12341234',
    'email' => 'test@web1.com'
  ],
  [
    'name' => 'name 3',
    'phone' => '4322342',
    'email' => 'test@web1.com'
  ],
  [
    'name' => 'name 4',
    'phone' => '1234123423',
    'email' => 'test@web1.com'
  ],
  [
    'name' => 'name 5',
    'phone' => '12341266634',
    'email' => 'test@eqweqwweb.com'
  ],
];

$phones = [];
$emails = [];
foreach ($data as $key => $contact) {
  if (array_search($contact['phone'], $phones) !== false || array_search($contact['email'], $emails) !== false) {
    unset($data[$key]);
  } else {
    $phones[] = $contact['phone'];
    $emails[] = $contact['email'];
  }
}

var_dump($data);

and in result you'll get:

array(3) {
  [0] =>
  array(3) {
    'name' =>
    string(6) "name 1"
    'phone' =>
    string(8) "12341234"
    'email' =>
    string(12) "test@web.com"
  }
  [2] =>
  array(3) {
    'name' =>
    string(6) "name 3"
    'phone' =>
    string(7) "4322342"
    'email' =>
    string(13) "test@web1.com"
  }
  [4] =>
  array(3) {
    'name' =>
    string(6) "name 5"
    'phone' =>
    string(11) "12341266634"
    'email' =>
    string(18) "test@eqweqwweb.com"
  }
}

this is just example.

How to find or count the duplicate in multidimensional array in c#

You can try HashSet<int>, e.g.

   int[,] arr = new int[3, 3] {
      {1, 2, 6 }, 
      {4, 1, 5 }, 
      {6, 1, 8 }
   };

   HashSet<int> unique = new HashSet<int>();

   foreach (var item in arr)
     if (!unique.Add(item))
       Console.WriteLine(item);  // Not unique, print it out

Outcome:

  1
  6
  1

If we want to print each duplicate once, we can add another HashSet<int>:

   HashSet<int> unique = new HashSet<int>();
   HashSet<int> duplicates = new HashSet<int>();

   foreach (var item in arr)
     if (!unique.Add(item))
       duplicates.Add(item);  

   foreach (var item in duplicates)
     Console.WriteLine(item);

Finally, if you want to count duplicate occurences we can change HashSet<int> duplicates into Dictionary<int, int> duplicates:

   HashSet<int> unique = new HashSet<int>();

   Dictionary<int, int> duplicates = new Dictionary<int, int>();

   foreach (var item in arr)
     if (!unique.Add(item)) 
       if (duplicates.TryGetValue(item, out int count))
         duplicates[item] = count + 1;
       else
         duplicates[item] = 2; 

   foreach (var item in duplicates)
     Console.WriteLine($"{item.Key} appears {item.Value} times");

Edit: you can change foreach loop into nested for ones, e.g:

All duplicates

   for (int i = 0; i < arr.GetLength(0); ++i)
     for (int j = 0; j < arr.GetLength(1); ++j)
       if (!unique.Add(arr[i, j]))
         Console.WriteLine(arr[i, j]);

Distinct duplicates

   HashSet<int> duplicates = new HashSet<int>();

   for (int i = 0; i < arr.GetLength(0); ++i)
     for (int j = 0; j < arr.GetLength(1); ++j)
       if (!unique.Add(arr[i, j]))
         if (duplicates.Add(arr[i, j]))   // print distinct duplicate only
           Console.WriteLine(arr[i, j]);

How to remove duplicate values from a multi-dimensional array in PHP

Here is another way. No intermediate variables are saved.

We used this to de-duplicate results from a variety of overlapping queries.

$input = array_map("unserialize", array_unique(array_map("serialize", $input)));

How can I get the duplicate multidimensional array in php

// first : get all data, if the data same / duplicate take only one data

$unique = array_unique($data, SORT_REGULAR);

// then, get the data which duplicate with

$diffCellUniq = array_diff_key($data, $unique);

// so print the result

print_r($diffCellUniq); exit;

Array
(
    [2] => Array
        (
            [a] => 1
            [b] => 2
            [c] => 3
            [d] => 4
        )

)