Online PHP editor | output for PpbXC

<?php $array = [ ['one' => 'data 1'], ['two' => 'data 2'], ['two' => 'data 3'], ['three' => 'data 4'], ['two' => 'data 5'], ['two' => 'data 6'], ['two' => 'data 7'], ['four' => 'data 8'], ]; $result = array_reduce($array, function ($c, $a) { $len = count($c); $key = key($a); if ($key == key($c[$len-1] ?? [])) { if (is_array($c[$len-1][$key])) { $c[$len-1][$key][]= $a[$key]; } else { $c[$len-1][$key] = array($c[$len-1][$key], $a[$key]); } } else { $c[] = $a; } return $c; }, []); print_r($result);