Как получить массив столбца PHPExcel?

$sheet = $objPHPExcel->getActiveSheet();
$array_data = array();
foreach($sheet->getRowIterator() as $row){
    $rowIndex = $row->getRowIndex ();
    $array_data[$rowIndex] = array('A'=>'', 'B'=>'','C'=>'','D'=>'');
     
    $cell = $sheet->getCell('A' . $rowIndex);
    $array_data[$rowIndex]['A'] = $cell->getCalculatedValue();
    $cell = $sheet->getCell('B' . $rowIndex);
    $array_data[$rowIndex]['B'] = $cell->getCalculatedValue();
    $cell = $sheet->getCell('C' . $rowIndex);
    $array_data[$rowIndex]['C'] = $cell->getCalculatedValue();
    $cell = $sheet->getCell('D' . $rowIndex);
    $array_data[$rowIndex]['D'] = $cell->getCalculatedValue();
}