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import numpy as np
from sklearn.utils.testing import (assert_allclose, assert_raises,
assert_equal)
from sklearn.neighbors import KernelDensity, KDTree, NearestNeighbors
from sklearn.neighbors.ball_tree import kernel_norm
from sklearn.pipeline import make_pipeline
from sklearn.datasets import make_blobs
from sklearn.model_selection import GridSearchCV
from sklearn.preprocessing import StandardScaler
def compute_kernel_slow(Y, X, kernel, h):
d = np.sqrt(((Y[:, None, :] - X) ** 2).sum(-1))
norm = kernel_norm(h, X.shape[1], kernel) / X.shape[0]
if kernel == 'gaussian':
return norm * np.exp(-0.5 * (d * d) / (h * h)).sum(-1)
elif kernel == 'tophat':
return norm * (d < h).sum(-1)
elif kernel == 'epanechnikov':
return norm * ((1.0 - (d * d) / (h * h)) * (d < h)).sum(-1)
elif kernel == 'exponential':
return norm * (np.exp(-d / h)).sum(-1)
elif kernel == 'linear':
return norm * ((1 - d / h) * (d < h)).sum(-1)
elif kernel == 'cosine':
return norm * (np.cos(0.5 * np.pi * d / h) * (d < h)).sum(-1)
else:
raise ValueError('kernel not recognized')
def test_kernel_density(n_samples=100, n_features=3):
rng = np.random.RandomState(0)
X = rng.randn(n_samples, n_features)
Y = rng.randn(n_samples, n_features)
for kernel in ['gaussian', 'tophat', 'epanechnikov',
'exponential', 'linear', 'cosine']:
for bandwidth in [0.01, 0.1, 1]:
dens_true = compute_kernel_slow(Y, X, kernel, bandwidth)
def check_results(kernel, bandwidth, atol, rtol):
kde = KernelDensity(kernel=kernel, bandwidth=bandwidth,
atol=atol, rtol=rtol)
log_dens = kde.fit(X).score_samples(Y)
assert_allclose(np.exp(log_dens), dens_true,
atol=atol, rtol=max(1E-7, rtol))
assert_allclose(np.exp(kde.score(Y)),
np.prod(dens_true),
atol=atol, rtol=max(1E-7, rtol))
for rtol in [0, 1E-5]:
for atol in [1E-6, 1E-2]:
for breadth_first in (True, False):
yield (check_results, kernel, bandwidth, atol, rtol)
def test_kernel_density_sampling(n_samples=100, n_features=3):
rng = np.random.RandomState(0)
X = rng.randn(n_samples, n_features)
bandwidth = 0.2
for kernel in ['gaussian', 'tophat']:
# draw a tophat sample
kde = KernelDensity(bandwidth, kernel=kernel).fit(X)
samp = kde.sample(100)
assert_equal(X.shape, samp.shape)
# check that samples are in the right range
nbrs = NearestNeighbors(n_neighbors=1).fit(X)
dist, ind = nbrs.kneighbors(X, return_distance=True)
if kernel == 'tophat':
assert np.all(dist < bandwidth)
elif kernel == 'gaussian':
# 5 standard deviations is safe for 100 samples, but there's a
# very small chance this test could fail.
assert np.all(dist < 5 * bandwidth)
# check unsupported kernels
for kernel in ['epanechnikov', 'exponential', 'linear', 'cosine']:
kde = KernelDensity(bandwidth, kernel=kernel).fit(X)
assert_raises(NotImplementedError, kde.sample, 100)
# non-regression test: used to return a scalar
X = rng.randn(4, 1)
kde = KernelDensity(kernel="gaussian").fit(X)
assert_equal(kde.sample().shape, (1, 1))
def test_kde_algorithm_metric_choice():
# Smoke test for various metrics and algorithms
rng = np.random.RandomState(0)
X = rng.randn(10, 2) # 2 features required for haversine dist.
Y = rng.randn(10, 2)
for algorithm in ['auto', 'ball_tree', 'kd_tree']:
for metric in ['euclidean', 'minkowski', 'manhattan',
'chebyshev', 'haversine']:
if algorithm == 'kd_tree' and metric not in KDTree.valid_metrics:
assert_raises(ValueError, KernelDensity,
algorithm=algorithm, metric=metric)
else:
kde = KernelDensity(algorithm=algorithm, metric=metric)
kde.fit(X)
y_dens = kde.score_samples(Y)
assert_equal(y_dens.shape, Y.shape[:1])
def test_kde_score(n_samples=100, n_features=3):
pass
#FIXME
#np.random.seed(0)
#X = np.random.random((n_samples, n_features))
#Y = np.random.random((n_samples, n_features))
def test_kde_badargs():
assert_raises(ValueError, KernelDensity,
algorithm='blah')
assert_raises(ValueError, KernelDensity,
bandwidth=0)
assert_raises(ValueError, KernelDensity,
kernel='blah')
assert_raises(ValueError, KernelDensity,
metric='blah')
assert_raises(ValueError, KernelDensity,
algorithm='kd_tree', metric='blah')
def test_kde_pipeline_gridsearch():
# test that kde plays nice in pipelines and grid-searches
X, _ = make_blobs(cluster_std=.1, random_state=1,
centers=[[0, 1], [1, 0], [0, 0]])
pipe1 = make_pipeline(StandardScaler(with_mean=False, with_std=False),
KernelDensity(kernel="gaussian"))
params = dict(kerneldensity__bandwidth=[0.001, 0.01, 0.1, 1, 10])
search = GridSearchCV(pipe1, param_grid=params, cv=5)
search.fit(X)
assert_equal(search.best_params_['kerneldensity__bandwidth'], .1)
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