3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = [ ['date' => '2017-08-22', 'AAA' => 1231], ['date' => '2017-08-21', 'AAA' => 1172], ['date' => '2017-08-20', 'AAA' => 1125], ['date' => '2017-08-21', 'BBB' => 251], ['date' => '2017-08-20', 'BBB' => 21773], ['date' => '2017-08-22', 'CCC' => 3750], ['date' => '2017-08-20', 'CCC' => 321750], ]; var_export( array_reduce( $array, function($accumulator, $row) { $date = $row['date']; unset($row['date']); $accumulator[$date] = array_merge($accumulator[$date] ?? [], $row); return $accumulator; }, [] ) );
Output for 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
array ( '2017-08-22' => array ( 'AAA' => 1231, 'CCC' => 3750, ), '2017-08-21' => array ( 'AAA' => 1172, 'BBB' => 251, ), '2017-08-20' => array ( 'AAA' => 1125, 'BBB' => 21773, 'CCC' => 321750, ), )
preferences:
113.92 ms | 1584 KiB | 4 Q