entropy_tests.py 文件源码

def _test_calculate_on_random_set(self, alpha, random_str):
        """
        Test utils.entropy on random set generated from alphanumerics.
        Note, this method presumes a uniform distribution from the
        stringer.random_string method.
        """
        STRING_LENGTH = len(random_str)
        ALPHA_LEN = len(alpha)

        ent_calc = self.ent.calculate(random_str)

        p = 1/ALPHA_LEN

        # this is the expected Shannon entropy for a uniform distribution
        exp_ent = STRING_LENGTH * p * log2(p)

        accepted_err = 10

        # why the hell is this failing?
        # assert_true(exp_ent-accepted_err <=
#                    ent_calc <=
 #                   exp_ent+accepted_err)