def test_iterative_imputer_verbose():
rng = np.random.RandomState(0)
n = 100
d = 3
X = _sparse_random_matrix(n, d, density=0.10, random_state=rng).toarray()
imputer = IterativeImputer(missing_values=0, max_iter=1, verbose=1)
imputer.fit(X)
imputer.transform(X)
imputer = IterativeImputer(missing_values=0, max_iter=1, verbose=2)
imputer.fit(X)
imputer.transform(X)
def test_iterative_imputer_additive_matrix():
rng = np.random.RandomState(0)
n = 100
d = 10
A = rng.randn(n, d)
B = rng.randn(n, d)
X_filled = np.zeros(A.shape)
for i in range(d):
for j in range(d):
X_filled[:, (i+j) % d] += (A[:, i] + B[:, j]) / 2
# a quarter is randomly missing
nan_mask = rng.rand(n, d) < 0.25
X_missing = X_filled.copy()
X_missing[nan_mask] = np.nan
# split up data
n = n // 2
X_train = X_missing[:n]
X_test_filled = X_filled[n:]
X_test = X_missing[n:]
imputer = IterativeImputer(max_iter=10,
verbose=1,
random_state=rng).fit(X_train)
X_test_est = imputer.transform(X_test)
assert_allclose(X_test_filled, X_test_est, rtol=1e-3, atol=0.01)
def test_iterative_imputer_truncated_normal_posterior():
# test that the values that are imputed using `sample_posterior=True`
# with boundaries (`min_value` and `max_value` are not None) are drawn
# from a distribution that looks gaussian via the Kolmogorov Smirnov test.
# note that starting from the wrong random seed will make this test fail
# because random sampling doesn't occur at all when the imputation
# is outside of the (min_value, max_value) range
pytest.importorskip("scipy", minversion="0.17.0")
rng = np.random.RandomState(42)
X = rng.normal(size=(5, 5))
X[0][0] = np.nan
imputer = IterativeImputer(min_value=0,
max_value=0.5,
sample_posterior=True,
random_state=rng)
imputer.fit_transform(X)
# generate multiple imputations for the single missing value
imputations = np.array([imputer.transform(X)[0][0] for _ in range(100)])
assert all(imputations >= 0)
assert all(imputations <= 0.5)
mu, sigma = imputations.mean(), imputations.std()
ks_statistic, p_value = kstest((imputations - mu) / sigma, 'norm')
if sigma == 0:
sigma += 1e-12
ks_statistic, p_value = kstest((imputations - mu) / sigma, 'norm')
# we want to fail to reject null hypothesis
# null hypothesis: distributions are the same
assert ks_statistic < 0.2 or p_value > 0.1, \
"The posterior does appear to be normal"
def test_iterative_imputer_transform_stochasticity():
pytest.importorskip("scipy", minversion="0.17.0")
rng1 = np.random.RandomState(0)
rng2 = np.random.RandomState(1)
n = 100
d = 10
X = _sparse_random_matrix(n, d, density=0.10,
random_state=rng1).toarray()
# when sample_posterior=True, two transforms shouldn't be equal
imputer = IterativeImputer(missing_values=0,
max_iter=1,
sample_posterior=True,
random_state=rng1)
imputer.fit(X)
X_fitted_1 = imputer.transform(X)
X_fitted_2 = imputer.transform(X)
# sufficient to assert that the means are not the same
assert np.mean(X_fitted_1) != pytest.approx(np.mean(X_fitted_2))
# when sample_posterior=False, and n_nearest_features=None
# and imputation_order is not random
# the two transforms should be identical even if rng are different
imputer1 = IterativeImputer(missing_values=0,
max_iter=1,
sample_posterior=False,
n_nearest_features=None,
imputation_order='ascending',
random_state=rng1)
imputer2 = IterativeImputer(missing_values=0,
max_iter=1,
sample_posterior=False,
n_nearest_features=None,
imputation_order='ascending',
random_state=rng2)
imputer1.fit(X)
imputer2.fit(X)
X_fitted_1a = imputer1.transform(X)
X_fitted_1b = imputer1.transform(X)
X_fitted_2 = imputer2.transform(X)
assert_allclose(X_fitted_1a, X_fitted_1b)
assert_allclose(X_fitted_1a, X_fitted_2)
def test_iterative_imputer_zero_iters():
rng = np.random.RandomState(0)
n = 100
d = 10
X = _sparse_random_matrix(n, d, density=0.10, random_state=rng).toarray()
missing_flag = X == 0
X[missing_flag] = np.nan
imputer = IterativeImputer(max_iter=0)
X_imputed = imputer.fit_transform(X)
# with max_iter=0, only initial imputation is performed
assert_allclose(X_imputed, imputer.initial_imputer_.transform(X))
# repeat but force n_iter_ to 0
imputer = IterativeImputer(max_iter=5).fit(X)
# transformed should not be equal to initial imputation
assert not np.all(imputer.transform(X) ==
imputer.initial_imputer_.transform(X))
imputer.n_iter_ = 0
# now they should be equal as only initial imputation is done
assert_allclose(imputer.transform(X),
imputer.initial_imputer_.transform(X))
def test_iterative_imputer_missing_at_transform(strategy):
rng = np.random.RandomState(0)
n = 100
d = 10
X_train = rng.randint(low=0, high=3, size=(n, d))
X_test = rng.randint(low=0, high=3, size=(n, d))
X_train[:, 0] = 1 # definitely no missing values in 0th column
X_test[0, 0] = 0 # definitely missing value in 0th column
imputer = IterativeImputer(missing_values=0,
max_iter=1,
initial_strategy=strategy,
random_state=rng).fit(X_train)
initial_imputer = SimpleImputer(missing_values=0,
strategy=strategy).fit(X_train)
# if there were no missing values at time of fit, then imputer will
# only use the initial imputer for that feature at transform
assert_allclose(imputer.transform(X_test)[:, 0],
initial_imputer.transform(X_test)[:, 0])
def test_iterative_imputer_transform_recovery(rank):
rng = np.random.RandomState(0)
n = 70
d = 70
A = rng.rand(n, rank)
B = rng.rand(rank, d)
X_filled = np.dot(A, B)
nan_mask = rng.rand(n, d) < 0.5
X_missing = X_filled.copy()
X_missing[nan_mask] = np.nan
# split up data in half
n = n // 2
X_train = X_missing[:n]
X_test_filled = X_filled[n:]
X_test = X_missing[n:]
imputer = IterativeImputer(max_iter=5,
imputation_order='descending',
verbose=1,
random_state=rng).fit(X_train)
X_test_est = imputer.transform(X_test)
assert_allclose(X_test_filled, X_test_est, atol=0.1)