Tiens marrant, il y a un module python en natif pour simplifier les fractions.

In [24]: from fractions import Fraction

In [27]: Fraction(2, 8)
Out[27]: Fraction(1, 4)

In [28]: print Fraction(2, 8)
1/4

In [29]: print str(int(Fraction(2, 8)))
0

In [30]: print str(float(Fraction(2, 8)))
0.25