compare two arrays and find the number of same elements

Question

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Find common values in multiple arrays with PHP

I have two arrays with the same indexes like ,

$a=Array
(
    [2013-01-15] => Array
        (
            [0] =>1001 
            [1] => 1002
            [2] => 1003
            [3] => 1004
            [4] => 1005
            [5] => 1006
            [6] => 1007
)
and 
$b=Array
(
    [2013-01-15] => Array
        (
            [0] =>1001 
            [1] => 
            [2] => 1003
            [3] => 
            [4] => 
            [5] => 1007
            [6] => 
)

Now I would like to compare this data and to find out how many number of same elements are there. In this case there are three elements in common.

What is the expected output? – Salman A Jan 28 '13 at 08:14 — Salman A, Jan 28 '13 at 08:14

score 4 · Accepted Answer · edited Jan 28 '13 at 08:21

4

Use array_intersect

$result = array_intersect($a['2013-01-15'], $b['2013-01-15']);

Example from manual:

$array1 = array("a" => "green", "red", "blue");
$array2 = array("b" => "green", "yellow", "red");
$result = array_intersect($array1, $array2);
print_r($result);  

Array
(
    [a] => green
    [0] => red
)

edited Jan 28 '13 at 08:21

Ben

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answered Jan 28 '13 at 08:14

Muhammad Raheel

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score 1 · Answer 2 · edited Jun 20 '20 at 09:12

Do you know the PHP array_intersect function? It might be what you are looking for...

array array_intersect ( array $array1 , array $array2 [, array $ ... ] )

array_intersect() retourne un tableau contenant toutes les valeurs de array1 qui sont présentes dans tous les autres arguments array2, ..., etc. Notez que les clés sont préservées.

You will need a flat array though. You can have a look at that question on how to do that: How to Flatten a Multidimensional Array?

In your case, provided your arrays are always made of array values and you need to count the duplicates within those:

$a = array( '2012-04' => array( 10, 50, 60, 80 ) );
$b = array( '2012-04' => array( 10, 40, 80 ) );

$count = 0;
foreach ( $a as $key => $array1 ) {
  if ( array_key_exists( $key, $b ) ) {
    $array2 = $b[ $key ];
    $count += count( array_intersect( $array1, $array2 ) );
  }
}

The data is two levels deep, `array_intersect` cannot be use as-is. — Salman A, Jan 28 '13 at 08:15
I know. However, flattening the array is not the hardest part. Edited the answer though. — Vincent Mimoun-Prat, Jan 28 '13 at 08:18

compare two arrays and find the number of same elements

2 Answers2