DOC add test for Geometric SMOTE (#881)

Author: joaopfonseca

imblearn/over_sampling/_smote/tests/test_geometric_smote.py

@@ -0,0 +1,209 @@
+"""
+Test the geometric_smote module.
+"""
+
+from collections import Counter
+
+import pytest
+import numpy as np
+from numpy.linalg import norm
+from sklearn.utils import check_random_state
+from sklearn.datasets import make_classification
+
+from ..geometric import _make_geometric_sample, GeometricSMOTE, SELECTION_STRATEGY
+
+RND_SEED = 0
+RANDOM_STATE = check_random_state(RND_SEED)
+CENTERS = [
+    RANDOM_STATE.random_sample((2,)),
+    2.6 * RANDOM_STATE.random_sample((4,)),
+    3.2 * RANDOM_STATE.random_sample((10,)),
+    -0.5 * RANDOM_STATE.random_sample((1,)),
+]
+SURFACE_POINTS = [
+    RANDOM_STATE.random_sample((2,)),
+    5.2 * RANDOM_STATE.random_sample((4,)),
+    -3.5 * RANDOM_STATE.random_sample((10,)),
+    -10.9 * RANDOM_STATE.random_sample((1,)),
+]
+TRUNCATION_FACTORS = [-1.0, -0.5, 0.0, 0.5, 1.0]
+DEFORMATION_FACTORS = [0.0, 0.25, 0.5, 0.75, 1.0]
+
+
+@pytest.mark.parametrize(
+    'center,surface_point',
+    [
+        (CENTERS[0], SURFACE_POINTS[0]),
+        (CENTERS[1], SURFACE_POINTS[1]),
+        (CENTERS[2], SURFACE_POINTS[2]),
+        (CENTERS[3], SURFACE_POINTS[3]),
+    ],
+)
+def test_make_geometric_sample_hypersphere(center, surface_point):
+    """Test the generation of points inside a hypersphere."""
+    point = _make_geometric_sample(center, surface_point, 0.0, 0.0, RANDOM_STATE)
+    rel_point = point - center
+    rel_surface_point = surface_point - center
+    np.testing.assert_array_less(0.0, norm(rel_surface_point) - norm(rel_point))
+
+
+@pytest.mark.parametrize(
+    'surface_point,deformation_factor',
+    [
+        (np.array([1.0, 0.0]), 0.0),
+        (2.6 * np.array([0.0, 1.0]), 0.25),
+        (3.2 * np.array([0.0, 1.0, 0.0, 0.0]), 0.50),
+        (0.5 * np.array([0.0, 0.0, 1.0]), 0.75),
+        (6.7 * np.array([0.0, 0.0, 1.0, 0.0, 0.0]), 1.0),
+    ],
+)
+def test_make_geometric_sample_half_hypersphere(surface_point, deformation_factor):
+    """Test the generation of points inside a hypersphere."""
+    center = np.zeros(surface_point.shape)
+    point = _make_geometric_sample(
+        center, surface_point, 1.0, deformation_factor, RANDOM_STATE
+    )
+    np.testing.assert_array_less(0.0, norm(surface_point) - norm(point))
+    np.testing.assert_array_less(0.0, np.dot(point, surface_point))
+
+
+@pytest.mark.parametrize(
+    'center,surface_point,truncation_factor',
+    [
+        (center, surface_point, truncation_factor)
+        for center, surface_point in zip(CENTERS, SURFACE_POINTS)
+        for truncation_factor in TRUNCATION_FACTORS
+    ],
+)
+def test_make_geometric_sample_line_segment(center, surface_point, truncation_factor):
+    """Test the generation of points on a line segment."""
+    point = _make_geometric_sample(
+        center, surface_point, truncation_factor, 1.0, RANDOM_STATE
+    )
+    rel_point = point - center
+    rel_surface_point = surface_point - center
+    dot_product = np.dot(rel_point, rel_surface_point)
+    norms_product = norm(rel_point) * norm(rel_surface_point)
+    np.testing.assert_array_less(0.0, norm(rel_surface_point) - norm(rel_point))
+    dot_product = (
+        np.abs(dot_product) if truncation_factor == 0.0 else (-1) * dot_product
+    )
+    np.testing.assert_allclose(np.abs(dot_product) / norms_product, 1.0)
+
+
+def test_gsmote_default_init():
+    """Test the intialization with default parameters."""
+    gsmote = GeometricSMOTE()
+    assert gsmote.sampling_strategy == 'auto'
+    assert gsmote.random_state is None
+    assert gsmote.truncation_factor == 1.0
+    assert gsmote.deformation_factor == 0.0
+    assert gsmote.selection_strategy == 'combined'
+    assert gsmote.k_neighbors == 5
+    assert gsmote.n_jobs == 1
+
+
+def test_gsmote_fit():
+    """Test fit method."""
+    n_samples, weights = 200, [0.6, 0.4]
+    X, y = make_classification(
+        random_state=RND_SEED, n_samples=n_samples, weights=weights
+    )
+    gsmote = GeometricSMOTE(random_state=RANDOM_STATE).fit(X, y)
+    assert gsmote.sampling_strategy_ == {1: 40}
+
+
+def test_gsmote_invalid_selection_strategy():
+    """Test invalid selection strategy."""
+    n_samples, weights = 200, [0.6, 0.4]
+    X, y = make_classification(
+        random_state=RND_SEED, n_samples=n_samples, weights=weights
+    )
+    gsmote = GeometricSMOTE(random_state=RANDOM_STATE, selection_strategy='Minority')
+    with pytest.raises(ValueError):
+        gsmote.fit_resample(X, y)
+
+
+@pytest.mark.parametrize('selection_strategy', ['combined', 'minority', 'majority'])
+def test_gsmote_nn(selection_strategy):
+    """Test nearest neighbors object."""
+    n_samples, weights = 200, [0.6, 0.4]
+    X, y = make_classification(
+        random_state=RND_SEED, n_samples=n_samples, weights=weights
+    )
+    gsmote = GeometricSMOTE(
+        random_state=RANDOM_STATE, selection_strategy=selection_strategy
+    )
+    _ = gsmote.fit_resample(X, y)
+    if selection_strategy in ('minority', 'combined'):
+        assert gsmote.nns_pos_.n_neighbors == gsmote.k_neighbors + 1
+    if selection_strategy in ('majority', 'combined'):
+        assert gsmote.nn_neg_.n_neighbors == 1
+
+
+@pytest.mark.parametrize(
+    'selection_strategy, truncation_factor, deformation_factor',
+    [
+        (selection_strategy, truncation_factor, deformation_factor)
+        for selection_strategy in SELECTION_STRATEGY
+        for truncation_factor in TRUNCATION_FACTORS
+        for deformation_factor in DEFORMATION_FACTORS
+    ],
+)
+def test_gsmote_fit_resample_binary(
+    selection_strategy, truncation_factor, deformation_factor
+):
+    """Test fit and sample for binary class case."""
+    n_maj, n_min, step, min_coor, max_coor = 12, 5, 0.5, 0.0, 8.5
+    X = np.repeat(np.arange(min_coor, max_coor, step), 2).reshape(-1, 2)
+    y = np.concatenate([np.repeat(0, n_maj), np.repeat(1, n_min)])
+    radius = np.sqrt(0.5) * step
+    k_neighbors = 1
+    gsmote = GeometricSMOTE(
+        'auto',
+        RANDOM_STATE,
+        truncation_factor,
+        deformation_factor,
+        selection_strategy,
+        k_neighbors,
+    )
+    X_resampled, y_resampled = gsmote.fit_resample(X, y)
+    assert gsmote.sampling_strategy_ == {1: (n_maj - n_min)}
+    assert y_resampled.sum() == n_maj
+    np.testing.assert_array_less(X[n_maj - 1] - radius, X_resampled[n_maj + n_min])
+
+
+@pytest.mark.parametrize(
+    'selection_strategy, truncation_factor, deformation_factor',
+    [
+        (selection_strategy, truncation_factor, deformation_factor)
+        for selection_strategy in SELECTION_STRATEGY
+        for truncation_factor in TRUNCATION_FACTORS
+        for deformation_factor in DEFORMATION_FACTORS
+    ],
+)
+def test_gsmote_fit_resample_multiclass(
+    selection_strategy, truncation_factor, deformation_factor
+):
+    """Test fit and sample for multiclass case."""
+    n_samples, weights = 100, [0.75, 0.15, 0.10]
+    X, y = make_classification(
+        random_state=RND_SEED,
+        n_samples=n_samples,
+        weights=weights,
+        n_classes=3,
+        n_informative=5,
+    )
+    k_neighbors, majority_label = 1, 0
+    gsmote = GeometricSMOTE(
+        'auto',
+        RANDOM_STATE,
+        truncation_factor,
+        deformation_factor,
+        selection_strategy,
+        k_neighbors,
+    )
+    _, y_resampled = gsmote.fit_resample(X, y)
+    assert majority_label not in gsmote.sampling_strategy_.keys()
+    np.testing.assert_array_equal(np.unique(y), np.unique(y_resampled))
+    assert len(set(Counter(y_resampled).values())) == 1