def test_demcmc_tune_parameter(self):
"""Tests that validity of the tune setting is checked"""
with Model() as model:
Normal("n", mu=0, sigma=1, shape=(2,3))
step = DEMetropolis()
assert step.tune is None
step = DEMetropolis(tune='scaling')
assert step.tune == 'scaling'
step = DEMetropolis(tune='lambda')
assert step.tune == 'lambda'
with pytest.raises(ValueError):
DEMetropolis(tune='foo')
pass
def test_demcmc_warning_on_small_populations(self):
"""Test that a warning is raised when n_chains <= n_dims"""
with Model() as model:
Normal("n", mu=0, sigma=1, shape=(2,3))
with pytest.warns(UserWarning) as record:
sample(
draws=5, tune=5, chains=6, step=DEMetropolis(),
# make tests faster by not parallelizing; disable convergence warning
cores=1, compute_convergence_checks=False
)
pass
def test_parallelized_chains_are_random(self):
with Model() as model:
x = Normal("x", 0, 1)
for stepper in TestPopulationSamplers.steppers:
step = stepper()
trace = sample(chains=4, cores=4, draws=20, tune=0, step=DEMetropolis())
samples = np.array(trace.get_values("x", combine=False))[:, 5]
assert len(set(samples)) == 4, "Parallelized {} " "chains are identical.".format(
stepper
)
pass