Online PHP editor | refs for BBZ2N

<?php $array = [ [ 'parent' => 'Basic', 'parentId' => 1, 'child' => 'Birthday', 'childId' => 2, ], [ 'parent' => 'Basic', 'parentId' => 1, 'child' => 'Gender', 'childId' => 3, ], [ 'parent' => 'Geo', 'parentId' => 10, 'child' => 'Current City', 'childId' => 11, ], [ 'parent' => 'Known me', 'parentId' => 5, 'child' => 'My personality', 'childId' => 7, ], [ 'parent' => 'Known me', 'parentId' => 5, 'child' => 'Best life moment', 'childId' => 8, ], ]; $result = []; foreach ($array as $row) { if (!isset($result[$row['parentId']])) { unset($row['childId']); $row['child'] = (array) $row['child']; $result[$row['parentId']] = $row; } else { $result[$row['parentId']]['child'][] = $row['child']; } } var_export(array_values($result));