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<?php $phones = [ 'Apple iPhone 4', 'Apple iPhone 5', 'Samsung Galaxy S6' ]; var_export( array_reduce( $phones, function($result, $item) { [ $key, $result[$key][] ] = explode(' ', $item, 2); return $result; }, ) );
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
array ( 'Apple' => array ( 0 => 'iPhone 4', 1 => 'iPhone 5', ), 'Samsung' => array ( 0 => 'Galaxy S6', ), )

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