>>> print "-- %2$s -- %1$s --" % ('a', 'b')
Python isn't C you know! You can't simply copy things from C to Python and
expect them to work.
Take a look at...
http://www.python.org/doc/current/lib/typesseq-strings.html
And you'll see that what you actually want is just...
>>> print "-- %s -- %s --" % ('a', 'b')
HTH,
Andrew