Suffix String with file name using php

public function filename_suffix($path,$suffix='')
{
$parts = pathinfo($path);
return $parts['dirname'].'/'.$parts['filename'].$suffix.'.'.$parts['extension'];
}

$f = pathinfo('http://cdn.shopify.com/s/files/1/0229/6827/products/tata_compact.jpg?100');
filename_suffix($f,$suffix='_thumb');