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import numpy as np
import pytest
from sklearn.cluster import KMeans, MiniBatchKMeans
from sklearn.datasets import make_classification
from sklearn.neighbors import NearestNeighbors
from sklearn.utils._testing import assert_allclose, assert_array_equal
from imblearn.over_sampling import SMOTE, KMeansSMOTE
@pytest.fixture
def data():
X = np.array(
[
[0.11622591, -0.0317206],
[0.77481731, 0.60935141],
[1.25192108, -0.22367336],
[0.53366841, -0.30312976],
[1.52091956, -0.49283504],
[-0.28162401, -2.10400981],
[0.83680821, 1.72827342],
[0.3084254, 0.33299982],
[0.70472253, -0.73309052],
[0.28893132, -0.38761769],
[1.15514042, 0.0129463],
[0.88407872, 0.35454207],
[1.31301027, -0.92648734],
[-1.11515198, -0.93689695],
[-0.18410027, -0.45194484],
[0.9281014, 0.53085498],
[-0.14374509, 0.27370049],
[-0.41635887, -0.38299653],
[0.08711622, 0.93259929],
[1.70580611, -0.11219234],
]
)
y = np.array([0, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 0])
return X, y
@pytest.mark.filterwarnings("ignore:The default value of `n_init` will change")
def test_kmeans_smote(data):
X, y = data
kmeans_smote = KMeansSMOTE(
kmeans_estimator=1,
random_state=42,
cluster_balance_threshold=0.0,
k_neighbors=5,
)
smote = SMOTE(random_state=42)
X_res_1, y_res_1 = kmeans_smote.fit_resample(X, y)
X_res_2, y_res_2 = smote.fit_resample(X, y)
assert_allclose(X_res_1, X_res_2)
assert_array_equal(y_res_1, y_res_2)
assert kmeans_smote.nn_k_.n_neighbors == 6
assert kmeans_smote.kmeans_estimator_.n_clusters == 1
assert "batch_size" in kmeans_smote.kmeans_estimator_.get_params()
@pytest.mark.filterwarnings("ignore:The default value of `n_init` will change")
@pytest.mark.parametrize("k_neighbors", [2, NearestNeighbors(n_neighbors=3)])
@pytest.mark.parametrize(
"kmeans_estimator",
[
3,
KMeans(n_clusters=3, n_init=1, random_state=42),
MiniBatchKMeans(n_clusters=3, n_init=1, random_state=42),
],
)
def test_sample_kmeans_custom(data, k_neighbors, kmeans_estimator):
X, y = data
kmeans_smote = KMeansSMOTE(
random_state=42,
kmeans_estimator=kmeans_estimator,
k_neighbors=k_neighbors,
)
X_resampled, y_resampled = kmeans_smote.fit_resample(X, y)
assert X_resampled.shape == (24, 2)
assert y_resampled.shape == (24,)
assert kmeans_smote.nn_k_.n_neighbors == 3
assert kmeans_smote.kmeans_estimator_.n_clusters == 3
@pytest.mark.filterwarnings("ignore:The default value of `n_init` will change")
def test_sample_kmeans_not_enough_clusters(data):
X, y = data
smote = KMeansSMOTE(cluster_balance_threshold=10, random_state=42)
with pytest.raises(RuntimeError):
smote.fit_resample(X, y)
@pytest.mark.parametrize("density_exponent", ["auto", 10])
@pytest.mark.parametrize("cluster_balance_threshold", ["auto", 0.1])
def test_sample_kmeans_density_estimation(density_exponent, cluster_balance_threshold):
X, y = make_classification(
n_samples=10_000, n_classes=2, weights=[0.3, 0.7], random_state=42
)
smote = KMeansSMOTE(
kmeans_estimator=MiniBatchKMeans(n_init=1, random_state=42),
random_state=0,
density_exponent=density_exponent,
cluster_balance_threshold=cluster_balance_threshold,
)
smote.fit_resample(X, y)
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