Online PHP editor | refs for NvLB8

<?php $array = Array ( 0 => Array ( 'date' => '2017-08-22', 'AAA' => '1231', ), 1 => Array ( 'date' => '2017-08-21', 'AAA' => '1172', ), 2 => Array ( 'date' => '2017-08-20', 'AAA' => '1125' ), 3 => Array ( 'date' => '2017-08-21', 'BBB' => '251' ), 4 => Array ( 'date' => '2017-08-20', 'BBB' => '21773', ), 5 => Array ( 'date' => '2017-08-22', 'CCC' => '3750' ), 6 => Array ( 'date' => '2017-08-20', 'CCC' => '321750' ) ); echo '<pre>'; $array1 = array('AAA' => null, 'BBB' => null, 'CCC' => null); $array2 = array(); array_walk($array, function ($v) use (&$array2, $array1) { $a = $v['date']; if (!isset($array2[$a])) { $array2[$a] = $array1; } unset($v['date']); $array2[$a] = array_merge($array2[$a], $v); }); print_r($array2);