convert 2d array to a string using php

Question

I have the following array

 01 03 02 15
 05 04 06 10
 07 09 08 11
 12 14 13 16

I want to convert a string like the following:

Answer 1

$input = array(
    array('01', '02', '03', '04'),
    array('11', '12', '13', '14'),
    array('21', '22', '23', '24'),
    array('31', '32', '33', '34'),
);
$newArray = array();
foreach($input as $rowIndex => $row) {
    foreach($row as $key => $val) {
        if(!$newArray[$key]) {
            $newArray[$key] = array();
        }
        $newArray[$key][$rowIndex] = $val;
    }
}
$strRows = array();
foreach($newArray as $key => $row) {
    $strRows[$key] = join(',', $row);
}
$output = join('|', $strRows);