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

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