def test_n_iter_without_progress():
# Use a dummy negative n_iter_without_progress and check output on stdout
random_state = check_random_state(0)
X = random_state.randn(100, 10)
for method in ["barnes_hut", "exact"]:
tsne = TSNE(n_iter_without_progress=-1,
verbose=2,
learning_rate=1e8,
random_state=0,
method=method,
n_iter=351,
init="random")
tsne._N_ITER_CHECK = 1
tsne._EXPLORATION_N_ITER = 0
old_stdout = sys.stdout
sys.stdout = StringIO()
try:
tsne.fit_transform(X)
finally:
out = sys.stdout.getvalue()
sys.stdout.close()
sys.stdout = old_stdout
# The output needs to contain the value of n_iter_without_progress
assert ("did not make any progress during the "
"last -1 episodes. Finished." in out)
def test_early_exaggeration_used():
# check that the ``early_exaggeration`` parameter has an effect
random_state = check_random_state(0)
n_components = 2
methods = ['exact', 'barnes_hut']
X = random_state.randn(25, n_components).astype(np.float32)
for method in methods:
tsne = TSNE(n_components=n_components,
perplexity=1,
learning_rate=100.0,
init="pca",
random_state=0,
method=method,
early_exaggeration=1.0,
n_iter=250)
X_embedded1 = tsne.fit_transform(X)
tsne = TSNE(n_components=n_components,
perplexity=1,
learning_rate=100.0,
init="pca",
random_state=0,
method=method,
early_exaggeration=10.0,
n_iter=250)
X_embedded2 = tsne.fit_transform(X)
assert not np.allclose(X_embedded1, X_embedded2)
def test_accessible_kl_divergence():
# Ensures that the accessible kl_divergence matches the computed value
random_state = check_random_state(0)
X = random_state.randn(50, 2)
tsne = TSNE(n_iter_without_progress=2,
verbose=2,
random_state=0,
method='exact',
n_iter=500)
old_stdout = sys.stdout
sys.stdout = StringIO()
try:
tsne.fit_transform(X)
finally:
out = sys.stdout.getvalue()
sys.stdout.close()
sys.stdout = old_stdout
# The output needs to contain the accessible kl_divergence as the error at
# the last iteration
for line in out.split('\n')[::-1]:
if 'Iteration' in line:
_, _, error = line.partition('error = ')
if error:
error, _, _ = error.partition(',')
break
assert_almost_equal(tsne.kl_divergence_, float(error), decimal=5)
def test_uniform_grid(method):
"""Make sure that TSNE can approximately recover a uniform 2D grid
Due to ties in distances between point in X_2d_grid, this test is platform
dependent for ``method='barnes_hut'`` due to numerical imprecision.
Also, t-SNE is not assured to converge to the right solution because bad
initialization can lead to convergence to bad local minimum (the
optimization problem is non-convex). To avoid breaking the test too often,
we re-run t-SNE from the final point when the convergence is not good
enough.
"""
seeds = [0, 1, 2]
n_iter = 500
for seed in seeds:
tsne = TSNE(n_components=2,
init='random',
random_state=seed,
perplexity=20,
n_iter=n_iter,
method=method)
Y = tsne.fit_transform(X_2d_grid)
try_name = "{}_{}".format(method, seed)
try:
assert_uniform_grid(Y, try_name)
except AssertionError:
# If the test fails a first time, re-run with init=Y to see if
# this was caused by a bad initialization. Note that this will
# also run an early_exaggeration step.
try_name += ":rerun"
tsne.init = Y
Y = tsne.fit_transform(X_2d_grid)
assert_uniform_grid(Y, try_name)
def test_pca_initialization_not_compatible_with_precomputed_kernel():
# Precomputed distance matrices must be square matrices.
tsne = TSNE(metric="precomputed", init="pca")
with pytest.raises(ValueError,
match="The parameter init=\"pca\" cannot"
" be used with"
" metric=\"precomputed\"."):
tsne.fit_transform(np.array([[0.0], [1.0]]))
def test_high_perplexity_precomputed_sparse_distances():
# Perplexity should be less than 50
dist = np.array([[1., 0., 0.], [0., 1., 0.], [1., 0., 0.]])
bad_dist = sp.csr_matrix(dist)
tsne = TSNE(metric="precomputed")
msg = "3 neighbors per samples are required, but some samples have only 1"
with pytest.raises(ValueError, match=msg):
tsne.fit_transform(bad_dist)
def test_angle_out_of_range_checks():
# check the angle parameter range
for angle in [-1, -1e-6, 1 + 1e-6, 2]:
tsne = TSNE(angle=angle)
with pytest.raises(ValueError,
match="'angle' must be between "
"0.0 - 1.0"):
tsne.fit_transform(np.array([[0.0], [1.0]]))
def test_distance_not_available():
# 'metric' must be valid.
tsne = TSNE(metric="not available", method='exact')
with pytest.raises(ValueError, match="Unknown metric not available.*"):
tsne.fit_transform(np.array([[0.0], [1.0]]))
tsne = TSNE(metric="not available", method='barnes_hut')
with pytest.raises(ValueError, match="Metric 'not available' not valid.*"):
tsne.fit_transform(np.array([[0.0], [1.0]]))
def test_non_positive_computed_distances():
# Computed distance matrices must be positive.
def metric(x, y):
return -1
tsne = TSNE(metric=metric, method='exact')
X = np.array([[0.0, 0.0], [1.0, 1.0]])
with pytest.raises(ValueError, match="All distances .*metric given.*"):
tsne.fit_transform(X)
def test_optimization_minimizes_kl_divergence():
"""t-SNE should give a lower KL divergence with more iterations."""
random_state = check_random_state(0)
X, _ = make_blobs(n_features=3, random_state=random_state)
kl_divergences = []
for n_iter in [250, 300, 350]:
tsne = TSNE(n_components=2,
perplexity=10,
learning_rate=100.0,
n_iter=n_iter,
random_state=0)
tsne.fit_transform(X)
kl_divergences.append(tsne.kl_divergence_)
assert kl_divergences[1] <= kl_divergences[0]
assert kl_divergences[2] <= kl_divergences[1]
def test_kl_divergence_not_nan(method):
# Ensure kl_divergence_ is computed at last iteration
# even though n_iter % n_iter_check != 0, i.e. 1003 % 50 != 0
random_state = check_random_state(0)
X = random_state.randn(50, 2)
tsne = TSNE(n_components=2,
perplexity=2,
learning_rate=100.0,
random_state=0,
method=method,
verbose=0,
n_iter=503)
tsne.fit_transform(X)
assert not np.isnan(tsne.kl_divergence_)
def test_n_iter_used():
# check that the ``n_iter`` parameter has an effect
random_state = check_random_state(0)
n_components = 2
methods = ['exact', 'barnes_hut']
X = random_state.randn(25, n_components).astype(np.float32)
for method in methods:
for n_iter in [251, 500]:
tsne = TSNE(n_components=n_components,
perplexity=1,
learning_rate=0.5,
init="random",
random_state=0,
method=method,
early_exaggeration=1.0,
n_iter=n_iter)
tsne.fit_transform(X)
assert tsne.n_iter_ == n_iter - 1
def test_sparse_precomputed_distance():
"""Make sure that TSNE works identically for sparse and dense matrix"""
random_state = check_random_state(0)
X = random_state.randn(100, 2)
D_sparse = kneighbors_graph(X,
n_neighbors=100,
mode='distance',
include_self=True)
D = pairwise_distances(X)
assert sp.issparse(D_sparse)
assert_almost_equal(D_sparse.A, D)
tsne = TSNE(metric="precomputed", random_state=0)
Xt_dense = tsne.fit_transform(D)
for fmt in ['csr', 'lil']:
Xt_sparse = tsne.fit_transform(D_sparse.asformat(fmt))
assert_almost_equal(Xt_dense, Xt_sparse)
def test_min_grad_norm():
# Make sure that the parameter min_grad_norm is used correctly
random_state = check_random_state(0)
X = random_state.randn(100, 2)
min_grad_norm = 0.002
tsne = TSNE(min_grad_norm=min_grad_norm,
verbose=2,
random_state=0,
method='exact')
old_stdout = sys.stdout
sys.stdout = StringIO()
try:
tsne.fit_transform(X)
finally:
out = sys.stdout.getvalue()
sys.stdout.close()
sys.stdout = old_stdout
lines_out = out.split('\n')
# extract the gradient norm from the verbose output
gradient_norm_values = []
for line in lines_out:
# When the computation is Finished just an old gradient norm value
# is repeated that we do not need to store
if 'Finished' in line:
break
start_grad_norm = line.find('gradient norm')
if start_grad_norm >= 0:
line = line[start_grad_norm:]
line = line.replace('gradient norm = ', '').split(' ')[0]
gradient_norm_values.append(float(line))
# Compute how often the gradient norm is smaller than min_grad_norm
gradient_norm_values = np.array(gradient_norm_values)
n_smaller_gradient_norms = \
len(gradient_norm_values[gradient_norm_values <= min_grad_norm])
# The gradient norm can be smaller than min_grad_norm at most once,
# because in the moment it becomes smaller the optimization stops
assert n_smaller_gradient_norms <= 1
def test_verbose():
# Verbose options write to stdout.
random_state = check_random_state(0)
tsne = TSNE(verbose=2)
X = random_state.randn(5, 2)
old_stdout = sys.stdout
sys.stdout = StringIO()
try:
tsne.fit_transform(X)
finally:
out = sys.stdout.getvalue()
sys.stdout.close()
sys.stdout = old_stdout
assert ("[t-SNE]" in out)
assert ("nearest neighbors..." in out)
assert ("Computed conditional probabilities" in out)
assert ("Mean sigma" in out)
assert ("early exaggeration" in out)
def test_preserve_trustworthiness_approximately(method, init):
# Nearest neighbors should be preserved approximately.
random_state = check_random_state(0)
n_components = 2
X = random_state.randn(50, n_components).astype(np.float32)
tsne = TSNE(n_components=n_components,
init=init,
random_state=0,
method=method,
n_iter=700)
X_embedded = tsne.fit_transform(X)
t = trustworthiness(X, X_embedded, n_neighbors=1)
assert t > 0.85
def test_fit_csr_matrix(method):
# X can be a sparse matrix.
rng = check_random_state(0)
X = rng.randn(50, 2)
X[(rng.randint(0, 50, 25), rng.randint(0, 2, 25))] = 0.0
X_csr = sp.csr_matrix(X)
tsne = TSNE(n_components=2,
perplexity=10,
learning_rate=100.0,
random_state=0,
method=method,
n_iter=750)
X_embedded = tsne.fit_transform(X_csr)
assert_allclose(trustworthiness(X_csr, X_embedded, n_neighbors=1),
1.0,
rtol=1.1e-1)
def test_preserve_trustworthiness_approximately_with_precomputed_distances():
# Nearest neighbors should be preserved approximately.
random_state = check_random_state(0)
for i in range(3):
X = random_state.randn(80, 2)
D = squareform(pdist(X), "sqeuclidean")
tsne = TSNE(n_components=2,
perplexity=2,
learning_rate=100.0,
early_exaggeration=2.0,
metric="precomputed",
random_state=i,
verbose=0,
n_iter=500)
X_embedded = tsne.fit_transform(D)
t = trustworthiness(D, X_embedded, n_neighbors=1, metric="precomputed")
assert t > .95
def test_64bit(method, dt):
# Ensure 64bit arrays are handled correctly.
random_state = check_random_state(0)
X = random_state.randn(10, 2).astype(dt, copy=False)
tsne = TSNE(n_components=2,
perplexity=2,
learning_rate=100.0,
random_state=0,
method=method,
verbose=0,
n_iter=300)
X_embedded = tsne.fit_transform(X)
effective_type = X_embedded.dtype
# tsne cython code is only single precision, so the output will
# always be single precision, irrespectively of the input dtype
assert effective_type == np.float32
def test_tsne():
# Test chaining KNeighborsTransformer and TSNE
n_iter = 250
perplexity = 5
n_neighbors = int(3. * perplexity + 1)
rng = np.random.RandomState(0)
X = rng.randn(20, 2)
for metric in ['minkowski', 'sqeuclidean']:
# compare the chained version and the compact version
est_chain = make_pipeline(
KNeighborsTransformer(n_neighbors=n_neighbors, mode='distance',
metric=metric),
TSNE(metric='precomputed', perplexity=perplexity,
method="barnes_hut", random_state=42, n_iter=n_iter))
est_compact = TSNE(metric=metric, perplexity=perplexity, n_iter=n_iter,
method="barnes_hut", random_state=42)
Xt_chain = est_chain.fit_transform(X)
Xt_compact = est_compact.fit_transform(X)
assert_array_almost_equal(Xt_chain, Xt_compact)
def test_bh_match_exact():
# check that the ``barnes_hut`` method match the exact one when
# ``angle = 0`` and ``perplexity > n_samples / 3``
random_state = check_random_state(0)
n_features = 10
X = random_state.randn(30, n_features).astype(np.float32)
X_embeddeds = {}
n_iter = {}
for method in ['exact', 'barnes_hut']:
tsne = TSNE(n_components=2,
method=method,
learning_rate=1.0,
init="random",
random_state=0,
n_iter=251,
perplexity=30.0,
angle=0)
# Kill the early_exaggeration
tsne._EXPLORATION_N_ITER = 0
X_embeddeds[method] = tsne.fit_transform(X)
n_iter[method] = tsne.n_iter_
assert n_iter['exact'] == n_iter['barnes_hut']
assert_allclose(X_embeddeds['exact'], X_embeddeds['barnes_hut'], rtol=1e-4)
def test_early_exaggeration_too_small():
# Early exaggeration factor must be >= 1.
tsne = TSNE(early_exaggeration=0.99)
with pytest.raises(ValueError, match="early_exaggeration .*"):
tsne.fit_transform(np.array([[0.0], [0.0]]))
def test_too_few_iterations():
# Number of gradient descent iterations must be at least 200.
tsne = TSNE(n_iter=199)
with pytest.raises(ValueError, match="n_iter .*"):
tsne.fit_transform(np.array([[0.0], [0.0]]))
def test_bad_precomputed_distances(method, D, retype, message_regex):
tsne = TSNE(metric="precomputed", method=method)
with pytest.raises(ValueError, match=message_regex):
tsne.fit_transform(retype(D))
def test_chebyshev_metric():
# t-SNE should allow metrics that cannot be squared (issue #3526).
random_state = check_random_state(0)
tsne = TSNE(metric="chebyshev")
X = random_state.randn(5, 2)
tsne.fit_transform(X)
def test_exact_no_precomputed_sparse():
tsne = TSNE(metric='precomputed', method='exact')
with pytest.raises(TypeError, match='sparse'):
tsne.fit_transform(sp.csr_matrix([[0, 5], [5, 0]]))
def test_init_not_available():
# 'init' must be 'pca', 'random', or numpy array.
tsne = TSNE(init="not available")
m = "'init' must be 'pca', 'random', or a numpy array"
with pytest.raises(ValueError, match=m):
tsne.fit_transform(np.array([[0.0], [1.0]]))
def test_init_ndarray():
# Initialize TSNE with ndarray and test fit
tsne = TSNE(init=np.zeros((100, 2)))
X_embedded = tsne.fit_transform(np.ones((100, 5)))
assert_array_equal(np.zeros((100, 2)), X_embedded)
def test_n_components_range():
# barnes_hut method should only be used with n_components <= 3
tsne = TSNE(n_components=4, method="barnes_hut")
with pytest.raises(ValueError, match="'n_components' should be .*"):
tsne.fit_transform(np.array([[0.0], [1.0]]))
def test_method_not_available():
# 'nethod' must be 'barnes_hut' or 'exact'
tsne = TSNE(method='not available')
with pytest.raises(ValueError, match="'method' must be 'barnes_hut' or "):
tsne.fit_transform(np.array([[0.0], [1.0]]))