How to transpose an array in PHP with irregular subarray size?

    function transposeCsvData($data)
    {
	    $ct=0;
	    foreach($data as $key => $val)
        {
	        //echo count($val);
		    if($ct< count($val))
                $ct=count($val);
		    }
		//echo $ct;
	    $blank=array_fill(0,$ct,array_fill(0,count($data),null));
	    //print_r($blank);
	
	    $retData = array();
        foreach ($data as $row => $columns)
        {
            foreach ($columns as $row2 => $column2) 
            {
                $retData[$row2][$row] = $column2;
                }
            }
	    $final=array();
	    foreach($retData as $k=>$aval)
	    { 
            $final[]=array_replace($blank[$k], $aval);
           }
        return $final;
        }

$a[]=array("name","john","sam","patrick");
$a[]=array("color","orange","green");
$a[]=array("bikes","suzuki","audi","mercedes","bmw","volks","rover");
$a[]=array("techgiants","samsung","amazon");

print_r(transposeCsvData($a));

Array
(
    [0] => Array
        (
            [0] => name
            [1] => color
            [2] => bikes
            [3] => techgiants
        )

    [1] => Array
        (
            [0] => john
            [1] => orange
            [2] => suzuki
            [3] => samsung
        )

    [2] => Array
        (
            [0] => sam
            [1] => green
            [2] => audi
            [3] => amazon
        )

    [3] => Array
        (
            [0] => patrick
            [1] => 
            [2] => mercedes
            [3] => 
        )

    [4] => Array
        (
            [0] => 
            [1] => 
            [2] => bmw
            [3] => 
        )

    [5] => Array
        (
            [0] => 
            [1] => 
            [2] => volks
            [3] => 
        )

    [6] => Array
        (
            [0] => 
            [1] => 
            [2] => rover
            [3] => 
        )

)