Online PHP editor | output for C8r1L

<?php $arrays = [ [ "sender" => "userA", "value" => 10, "function" => "deposit" ], [ "sender" => "userB", "value" => 5, "function" => "deposit" ], [ "sender" => "userA", "value" => 2, "function" => "withdraw" ], [ "sender" => "userA", "value" => 3, "function" => "deposit" ], [ "sender" => "userA", "value" => 20, "function" => "deposit" ], [ "sender" => "userC", "value" => 99, "function" => "withdraw" ] ]; $result = array_reduce($arrays, function ($acc, $curr) { if (array_key_exists($curr["sender"], $acc)) { if ($curr["function"] === "deposit") { $acc[$curr["sender"]] += $curr["value"]; } if ($curr["function"] === "withdraw") { $acc[$curr["sender"]] -= $curr["value"]; } } else { if ($curr["function"] === "deposit") { $acc[$curr["sender"]] = $curr["value"]; } if ($curr["function"] === "withdraw") { $acc[$curr["sender"]] = -1 * $curr["value"]; } } return $acc; }, []); print_r($result);