test_abc_smc_algorithm.py 文件源码

def test_beta_binomial_different_priors(db_path, sampler):
    binomial_n = 5

    def model(args):
        return {"result": st.binom(binomial_n, args['theta']).rvs()}

    models = [model for _ in range(2)]
    models = list(map(SimpleModel, models))
    population_size = ConstantPopulationSize(800)
    a1, b1 = 1, 1
    a2, b2 = 10, 1
    parameter_given_model_prior_distribution = [Distribution(theta=RV("beta",
                                                                      a1, b1)),
                                                Distribution(theta=RV("beta",
                                                                      a2, b2))]
    abc = ABCSMC(models, parameter_given_model_prior_distribution,
                 MinMaxDistanceFunction(measures_to_use=["result"]),
                 population_size,
                 eps=MedianEpsilon(.1),
                 sampler=sampler)
    n1 = 2
    abc.new(db_path, {"result": n1})

    minimum_epsilon = .2
    history = abc.run(minimum_epsilon, max_nr_populations=3)
    mp = history.get_model_probabilities(history.max_t)

    def B(a, b):
        return gamma(a) * gamma(b) / gamma(a + b)

    def expected_p(a, b, n1):
        return binom(binomial_n, n1) * B(a + n1, b + binomial_n - n1) / B(a, b)

    p1_expected_unnormalized = expected_p(a1, b1, n1)
    p2_expected_unnormalized = expected_p(a2, b2, n1)
    p1_expected = p1_expected_unnormalized / (p1_expected_unnormalized +
                                              p2_expected_unnormalized)
    p2_expected = p2_expected_unnormalized / (p1_expected_unnormalized +
                                              p2_expected_unnormalized)
    assert abs(mp.p[0] - p1_expected) + abs(mp.p[1] - p2_expected) < .08