Check same value in array

Question

I have the following array:

$teams = [["id" => 1, "address" => "A1"],["id" => 2, "address" => "A1"],["id" => 3, "address" => "A2"]];

How can I check and get the teams with the same address? My output should be Team ID 1 and 2? Consider that I cannot use hard coded address. The data is dynamic and is coming from the database.

In php, laravel.

Thank you in advance!

Answer 1

First you need to group by their address and then you can use array_filter() to truncate your array based on criteria:

<?php
$teams = [["id" => 1, "address" => "A1"],["id" => 2, "address" => "A1"],["id" => 3, "address" => "A2"]];

// Set a new array
$filtered = [];

// Loop the teams
foreach($teams as $v)
{
    // Group the teams into their respective addresses
    $filtered[$v['address']][] = $v;
}

// Filter out any address with 1 or fewer teams
$filtered = array_filter($filtered, function($v){
    return count($v) > 1;
});

print_r($filtered);

// Now you can loop $filtered and display whatever you want

Output:

Array
(
    [A1] => Array
        (
            [0] => Array
                (
                    [id] => 1
                    [address] => A1
                )

            [1] => Array
                (
                    [id] => 2
                    [address] => A1
                )

        )

)

Answer 2

Another way to do this is to use array_column() and array_count_values() . Then use array_filter() to remove elements with no duplicates:

$teams = [
 ["id" => 1, "address" => "A1"],
 ["id" => 2, "address" => "A1"] ,
 ["id" => 3, "address" => "A2"]
];

$dups = array_count_values(array_column($teams, 'address'));
$teams = array_filter($teams, function($item) use($dups) {
    return $dups[$item['address']] > 1;
});
print_r($teams);

Outputs (reformatted):

Array
(
    [0] => Array([id] => 1, [address] => A1)
    [1] => Array([id] => 2, [address] => A1)
)

Answer 3

Go through the array, remember which addresses are used by which team. When there is more than one team stored at a key (address), you found a duplicate:

<?php
$teams = [
     ["id" => 1, "address" => "A1"]
    ,["id" => 2, "address" => "A1"]
    ,["id" => 3, "address" => "A2"]
  ];

function findDuplicates($teams) {
  $addresses = [];
  foreach ($teams as $team) {
    if (!isset($addresses[$team["address"]])) {
      $addresses[$team["address"]] = [];
    }
    $addresses[$team["address"]][] = $team["id"];
  }
  foreach ($addresses as $address => $teamsHere) {
    if (count($teamsHere) > 1) {
      echo "Teams with same address (" . $address . "): " . join(",", $teamsHere) . "\n";
    }
  }
}

findDuplicates($teams);

Try it online!

---

Edit: a less "clunky" approach, using array_* functions:

<?php
$teams = [
     ["id" => 1, "address" => "A1"]
    ,["id" => 2, "address" => "A1"]
    ,["id" => 3, "address" => "A2"]
  ];

function findDuplicates($teams) {
  $addresses = array_column($teams, "address");
  $counts = array_count_values($addresses);
  return array_filter($teams, function($team) use ($counts) { return $counts[$team["address"]] > 1; });
}

print_r(findDuplicates($teams));

Try it online!