Division in Python 3 gives different result than in Python 2

Question

In the following code, I want to calculate the percent of G and C characters in a sequence. In Python 3 I correctly get 0.5, but on Python 2 I get 0

Answer 1

For Python2 / is integer division when the numerator and denominator are both int, you need to make sure to force floating point division

eg.

return (seq.count('G') + seq.count('C')) / float(len(seq))

alternatively, you can put

from __future__ import division

at the top of the file