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import numpy as np
from numpy.testing import assert_array_almost_equal
from sklearn.manifold import mds
from sklearn.utils.testing import assert_raises
def test_smacof():
# test metric smacof using the data of "Modern Multidimensional Scaling",
# Borg & Groenen, p 154
sim = np.array([[0, 5, 3, 4],
[5, 0, 2, 2],
[3, 2, 0, 1],
[4, 2, 1, 0]])
Z = np.array([[-.266, -.539],
[.451, .252],
[.016, -.238],
[-.200, .524]])
X, _ = mds.smacof(sim, init=Z, n_components=2, max_iter=1, n_init=1)
X_true = np.array([[-1.415, -2.471],
[1.633, 1.107],
[.249, -.067],
[-.468, 1.431]])
assert_array_almost_equal(X, X_true, decimal=3)
def test_smacof_error():
# Not symmetric similarity matrix:
sim = np.array([[0, 5, 9, 4],
[5, 0, 2, 2],
[3, 2, 0, 1],
[4, 2, 1, 0]])
assert_raises(ValueError, mds.smacof, sim)
# Not squared similarity matrix:
sim = np.array([[0, 5, 9, 4],
[5, 0, 2, 2],
[4, 2, 1, 0]])
assert_raises(ValueError, mds.smacof, sim)
# init not None and not correct format:
sim = np.array([[0, 5, 3, 4],
[5, 0, 2, 2],
[3, 2, 0, 1],
[4, 2, 1, 0]])
Z = np.array([[-.266, -.539],
[.016, -.238],
[-.200, .524]])
assert_raises(ValueError, mds.smacof, sim, init=Z, n_init=1)
def test_MDS():
sim = np.array([[0, 5, 3, 4],
[5, 0, 2, 2],
[3, 2, 0, 1],
[4, 2, 1, 0]])
mds_clf = mds.MDS(metric=False, n_jobs=3, dissimilarity="precomputed")
mds_clf.fit(sim)
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