Online PHP editor | refs for q1dli

<?php $bookInfo = array( 0 => array("bookId" => "1", "bookName" => "Book 1", "authorId" => 1, "authorName" => "Author 1") , 1=> array("bookId" => "1", "bookName" => "Book 1", "authorId" => 2, "authorName" => "Author 2") , 2=> array("bookId" => "2", "bookName" => "Book 2", "authorId" => 3, "authorName" => "Author 3") , 3=> array("bookId" => "3", "bookName" => "Book 3", "authorId" => 4, "authorName" => "Author 4") ); print_r($bookInfo); $newBookInfo = []; $newBookKey = []; $newKey = 0; foreach($bookInfo as $bookKey => $bookValue){ if(!in_array($bookValue["bookId"],$newBookKey)){ ++$newKey; $newBookInfo[$newKey]["bookId"] = $bookValue["bookId"]; $newBookInfo[$newKey]["bookName"] = $bookValue["bookName"]; } $newBookInfo[$newKey]["authorName"][$bookKey] = $bookValue["authorName"]; $newBookKey[] = $bookValue["bookId"]; } print_r($newBookInfo);