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

Looking at the solutions proposed so far, only one actually generates the correct output requested by the OP.

So, stealing unashamedly from salathe's neat conversion, but with a transpose to provide the correct result:

$input = array ( 
    array ('01','03','02','15'), 
    array ('05','04','06','10'), 
    array ('07','09','08','11'), 
    array ('12','14','13','16'), 
); 

function transpose($array) {
    array_unshift($array, null);
    return call_user_func_array('array_map', $array);
}

$transposed = transpose($input);

echo implode('|', array_map('implode', $transposed, array_fill(0, count($transposed), ',')));