def test_pr2bias(self): """CodonUsage pr2bias should give correct ratios.""" c = EqualBases.codons() b = c.pr2bias('UU') self.assertEqual(len(b), 6) self.assertEqual(b, tuple([.5]*6)) c = CodonUsage() c['ACU'] = 10 c['ACC'] = 5 c['ACA'] = 15 c['ACG'] = 20 self.assertEqual(c.pr2bias('AC'), (20/25,15/25,20/35,5/15,20/30,5/20))