How to pad zeroes to a string?

Question

What is a Pythonic way to pad a numeric string with zeroes to the left, i.e. so the numeric string has a specific length?

Answer 1

str(n).zfill(width) will work with strings, ints, floats... and is Python 2.x and 3.x compatible:

>>> n = 3
>>> str(n).zfill(5)
'00003'
>>> n = '3'
>>> str(n).zfill(5)
'00003'
>>> n = '3.0'
>>> str(n).zfill(5)
'003.0'