from __future__ import with_statement
from array import array

x = array('i', [1,2,3,4,5])
with open("test.data", "wb") as f:
    x.tofile(f)

x = array('i', [])
with open("test.data", "r+b") as f:
    x.fromfile(f, 5)
    x *= 2
    x.tofile(f)

with open("test.data", "rb") as f:
    x.fromfile(f, 10)
    print x