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"""
Testing for mean shift clustering methods
"""
import numpy as np
from numpy.testing import assert_equal
from nose.tools import assert_true
from .. import MeanShift, mean_shift, estimate_bandwidth, get_bin_seeds
from ...datasets.samples_generator import make_blobs
n_clusters = 3
centers = np.array([[1, 1], [-1, -1], [1, -1]]) + 10
X, _ = make_blobs(n_samples=500, n_features=2, centers=centers,
cluster_std=0.4, shuffle=True, random_state=0)
def test_mean_shift():
""" Test MeanShift algorithm
"""
bandwidth = 1.2
bandwidth_ = estimate_bandwidth(X, n_samples=300)
assert_true(0.9 <= bandwidth_ <= 1.5)
ms = MeanShift(bandwidth=bandwidth)
labels = ms.fit(X).labels_
cluster_centers = ms.cluster_centers_
labels_unique = np.unique(labels)
n_clusters_ = len(labels_unique)
assert_equal(n_clusters_, n_clusters)
cluster_centers, labels = mean_shift(X, bandwidth=bandwidth)
labels_unique = np.unique(labels)
n_clusters_ = len(labels_unique)
assert_equal(n_clusters_, n_clusters)
def test_bin_seeds():
"""
Test the bin seeding technique which can be used in the mean shift
algorithm
"""
# Data is just 6 points in the plane
X = np.array([[1., 1.], [1.5, 1.5], [1.8, 1.2],
[2., 1.], [2.1, 1.1], [0., 0.]])
# With a bin coarseness of 1.0 and min_bin_freq of 1, 3 bins should be
# found
ground_truth = set([(1., 1.), (2., 1.), (0., 0.)])
test_bins = get_bin_seeds(X, 1, 1)
test_result = set([tuple(p) for p in test_bins])
assert_true(len(ground_truth.symmetric_difference(test_result)) == 0)
# With a bin coarseness of 1.0 and min_bin_freq of 2, 2 bins should be
# found
ground_truth = set([(1., 1.), (2., 1.)])
test_bins = get_bin_seeds(X, 1, 2)
test_result = set([tuple(p) for p in test_bins])
assert_true(len(ground_truth.symmetric_difference(test_result)) == 0)
# With a bin size of 0.01 and min_bin_freq of 1, 6 bins should be found
test_bins = get_bin_seeds(X, 0.01, 1)
test_result = set([tuple(p) for p in test_bins])
assert_true(len(test_result) == 6)
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