def test_shrunk_covariance():
# Tests ShrunkCovariance module on a simple dataset.
# compare shrunk covariance obtained from data and from MLE estimate
cov = ShrunkCovariance(shrinkage=0.5)
cov.fit(X)
assert_array_almost_equal(
shrunk_covariance(empirical_covariance(X), shrinkage=0.5),
cov.covariance_, 4)
# same test with shrinkage not provided
cov = ShrunkCovariance()
cov.fit(X)
assert_array_almost_equal(shrunk_covariance(empirical_covariance(X)),
cov.covariance_, 4)
# same test with shrinkage = 0 (<==> empirical_covariance)
cov = ShrunkCovariance(shrinkage=0.)
cov.fit(X)
assert_array_almost_equal(empirical_covariance(X), cov.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
cov = ShrunkCovariance(shrinkage=0.3)
cov.fit(X_1d)
assert_array_almost_equal(empirical_covariance(X_1d), cov.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
cov = ShrunkCovariance(shrinkage=0.5, store_precision=False)
cov.fit(X)
assert (cov.precision_ is None)
def test_oas():
"""Tests OAS module on a simple dataset.
"""
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X, assume_centered=True)
assert_almost_equal(oa.shrinkage_, 0.018740, 4)
assert_almost_equal(oa.score(X, assume_centered=True), -5.03605, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X, assume_centered=True)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
oa = OAS()
oa.fit(X_1d, assume_centered=True)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X, assume_centered=True)
assert_almost_equal(oa.score(X, assume_centered=True), -5.03605, 4)
assert(oa.precision_ is None)
### Same tests without assuming centered data
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X)
assert_almost_equal(oa.shrinkage_, 0.020236, 4)
assert_almost_equal(oa.score(X), 2.079025, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
oa = OAS()
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X)
assert_almost_equal(oa.score(X), 2.079025, 4)
assert(oa.precision_ is None)
def test_shrunk_covariance():
"""Tests ShrunkCovariance module on a simple dataset.
"""
# compare shrunk covariance obtained from data and from MLE estimate
cov = ShrunkCovariance(shrinkage=0.5)
cov.fit(X)
assert_array_almost_equal(
shrunk_covariance(empirical_covariance(X), shrinkage=0.5),
cov.covariance_, 4)
# same test with shrinkage not provided
cov = ShrunkCovariance()
cov.fit(X)
assert_array_almost_equal(
shrunk_covariance(empirical_covariance(X)), cov.covariance_, 4)
# same test with shrinkage = 0 (<==> empirical_covariance)
cov = ShrunkCovariance(shrinkage=0.)
cov.fit(X)
assert_array_almost_equal(empirical_covariance(X), cov.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
cov = ShrunkCovariance(shrinkage=0.3)
cov.fit(X_1d)
assert_array_almost_equal(empirical_covariance(X_1d), cov.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
cov = ShrunkCovariance(shrinkage=0.5, store_precision=False)
cov.fit(X)
assert(cov.precision_ is None)
def precisionCol(cleandata, k):
"""Using precision matrix to choose useful attributes in high dimensional data"""
model = ShrunkCovariance()
model.fit(cleandata)
pre_ = pd.DataFrame(model.get_precision())
pre_.index = cleandata.columns
pre_.columns = cleandata.columns
test = abs(pre_['Y'])
test.sort()
test = test[-k:]
coltest = (test.index).drop('Y')
return coltest
def test_oas():
"""Tests OAS module on a simple dataset.
"""
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
oa = OAS(assume_centered=True)
oa.fit(X_centered)
shrinkage_ = oa.shrinkage_
score_ = oa.score(X_centered)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_centered,
assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS(assume_centered=True)
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False, assume_centered=True)
oa.fit(X_centered)
assert_almost_equal(oa.score(X_centered), score_, 4)
assert(oa.precision_ is None)
### Same tests without assuming centered data
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X)
assert_almost_equal(oa.shrinkage_, shrinkage_, 4)
assert_almost_equal(oa.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS()
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), oa.covariance_, 4)
# test with one sample
X_1sample = np.arange(5)
oa = OAS()
with warnings.catch_warnings(record=True):
oa.fit(X_1sample)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X)
assert_almost_equal(oa.score(X), score_, 4)
assert(oa.precision_ is None)
def test_ledoit_wolf():
"""Tests LedoitWolf module on a simple dataset.
"""
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
lw = LedoitWolf(assume_centered=True)
lw.fit(X_centered)
shrinkage_ = lw.shrinkage_
score_ = lw.score(X_centered)
assert_almost_equal(ledoit_wolf_shrinkage(X_centered,
assume_centered=True),
shrinkage_)
assert_almost_equal(ledoit_wolf_shrinkage(X_centered,
assume_centered=True, block_size=6),
shrinkage_)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_centered,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf(assume_centered=True)
lw.fit(X_1d)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False, assume_centered=True)
lw.fit(X_centered)
assert_almost_equal(lw.score(X_centered), score_, 4)
assert(lw.precision_ is None)
# (too) large data set
X_large = np.ones((20, 200))
assert_raises(MemoryError, ledoit_wolf, X_large, block_size=100)
# Same tests without assuming centered data
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X)
assert_almost_equal(lw.shrinkage_, shrinkage_, 4)
assert_almost_equal(lw.shrinkage_, ledoit_wolf_shrinkage(X))
assert_almost_equal(lw.shrinkage_, ledoit_wolf(X)[1])
assert_almost_equal(lw.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), lw.covariance_, 4)
# test with one sample
X_1sample = np.arange(5)
lw = LedoitWolf()
with warnings.catch_warnings(record=True):
lw.fit(X_1sample)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X)
assert_almost_equal(lw.score(X), score_, 4)
assert(lw.precision_ is None)
def test_oas():
# Tests OAS module on a simple dataset.
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
oa = OAS(assume_centered=True)
oa.fit(X_centered)
shrinkage_ = oa.shrinkage_
score_ = oa.score(X_centered)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X_centered,
assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0:1]
oa = OAS(assume_centered=True)
oa.fit(X_1d)
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X_1d, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
assert_array_almost_equal((X_1d**2).sum() / n_samples, oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False, assume_centered=True)
oa.fit(X_centered)
assert_almost_equal(oa.score(X_centered), score_, 4)
assert (oa.precision_ is None)
# Same tests without assuming centered data--------------------------------
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X)
assert_almost_equal(oa.shrinkage_, shrinkage_, 4)
assert_almost_equal(oa.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS()
oa.fit(X_1d)
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X_1d)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), oa.covariance_, 4)
# test with one sample
# warning should be raised when using only 1 sample
X_1sample = np.arange(5).reshape(1, 5)
oa = OAS()
warn_msg = (
"Only one sample available. You may want to reshape your data array")
with pytest.warns(UserWarning, match=warn_msg):
oa.fit(X_1sample)
assert_array_almost_equal(oa.covariance_,
np.zeros(shape=(5, 5), dtype=np.float64))
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X)
assert_almost_equal(oa.score(X), score_, 4)
assert (oa.precision_ is None)
class TemplateBeamformer(BaseNode):
'''
Spatio-temporal LCMV beamformer operating on a spatio-temporal template.
Parameters
----------
template : 2D array (n_channels, n_samples)
Spatio-temporal activation pattern of the component to extract.
shrinkage : str | float (default: 'oas')
Shrinkage parameter for the covariance matrix inversion. This can
either be speficied as a number between 0 and 1, or as a string
indicating which automated estimation method to use:
'none': No shrinkage: emperical covariance
'oas': Oracle approximation shrinkage
'lw': Ledoit-Wolf approximation shrinkage
center : bool (default: True)
Whether to remove the data mean before applying the filter.
'''
def __init__(self, template, shrinkage='oas', center=True):
BaseNode.__init__(self)
self.template = template
self.template = np.atleast_2d(template)
self.center = center
if center:
self.template -= self.template.mean()
if shrinkage == 'oas':
self.cov = OAS
elif shrinkage == 'lw':
self.cov = LedoitWolf
elif shrinkage == 'none':
self.cov = EmpiricalCovariance
elif type(shrinkage) == float or type(shrinkage) == int:
self.cov = ShrunkCovariance(shrinkage=shrinkage)
def _center(self, d):
data_mean = d.data.reshape(-1, len(d)).mean(axis=1)
data_mean = data_mean.reshape(d.feat_shape + (1,))
return DataSet(d.data - data_mean, default=d)
def train_(self, d):
if self.center:
d = self._center(d)
nsamples, ntrials = d.data.shape[1:]
template = self.template[:, :nsamples]
c = self.cov.fit(d.data.reshape(-1, ntrials).T)
sigma_x_i = c.precision_
template = self.template.flatten()[:, np.newaxis]
self.W = sigma_x_i.dot(template)
# Noise normalization
self.W = self.W.dot(
np.linalg.inv(reduce(np.dot, [template.T, sigma_x_i, template]))
)
def apply_(self, d):
if self.center:
d = self._center(d)
ntrials = d.data.shape[2]
X = self.W.T.dot(d.data.reshape(-1, ntrials))
return DataSet(data=X, feat_lab=None, default=d)
def test_oas():
# Tests OAS module on a simple dataset.
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
oa = OAS(assume_centered=True)
oa.fit(X_centered)
shrinkage_ = oa.shrinkage_
score_ = oa.score(X_centered)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_centered,
assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS(assume_centered=True)
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal((X_1d**2).sum() / n_samples, oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False, assume_centered=True)
oa.fit(X_centered)
assert_almost_equal(oa.score(X_centered), score_, 4)
assert (oa.precision_ is None)
# Same tests without assuming centered data--------------------------------
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X)
assert_almost_equal(oa.shrinkage_, shrinkage_, 4)
assert_almost_equal(oa.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS()
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), oa.covariance_, 4)
# test with one sample
# FIXME I don't know what this test does
X_1sample = np.arange(5)
oa = OAS()
assert_warns(UserWarning, oa.fit, X_1sample)
assert_array_almost_equal(oa.covariance_,
np.zeros(shape=(5, 5), dtype=np.float64))
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X)
assert_almost_equal(oa.score(X), score_, 4)
assert (oa.precision_ is None)
def test_ledoit_wolf():
"""Tests LedoitWolf module on a simple dataset.
"""
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X, assume_centered=True)
assert_almost_equal(lw.shrinkage_, 0.00192, 4)
assert_almost_equal(lw.score(X, assume_centered=True), -2.89795, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X, assume_centered=True)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d, assume_centered=True)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X, assume_centered=True)
assert_almost_equal(lw.score(X, assume_centered=True), -2.89795, 4)
assert(lw.precision_ is None)
# Same tests without assuming centered data
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X)
assert_almost_equal(lw.shrinkage_, 0.007582, 4)
assert_almost_equal(lw.score(X), 2.243483, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X)
assert_almost_equal(lw.score(X), 2.2434839, 4)
assert(lw.precision_ is None)
def fit(self, epochs_data, y):
"""Estimate the CSP decomposition on epochs.
Parameters
----------
epochs_data : array, shape=(n_epochs, n_channels, n_times)
The data to estimate the CSP on.
y : array
The class for each epoch.
Returns
-------
self : instance of CSP
Returns the modified instance.
"""
if not isinstance(epochs_data, np.ndarray):
raise ValueError(
"epochs_data should be of type ndarray (got %s)." %
type(epochs_data))
epochs_data = np.atleast_3d(epochs_data)
classes = np.unique(y)
if len(classes) != 2:
raise ValueError("More than two different classes in the data.")
# concatenate epochs
class_1 = np.transpose(epochs_data[y == classes[0]],
[1, 0, 2]).reshape(epochs_data.shape[1], -1)
class_2 = np.transpose(epochs_data[y == classes[1]],
[1, 0, 2]).reshape(epochs_data.shape[1], -1)
if self.reg is None:
# compute empirical covariance
cov_1 = np.dot(class_1, class_1.T)
cov_2 = np.dot(class_2, class_2.T)
else:
# use sklearn covariance estimators
if isinstance(self.reg, float):
if (self.reg < 0) or (self.reg > 1):
raise ValueError('0 <= shrinkage <= 1 for '
'covariance regularization.')
try:
import sklearn
sklearn_version = LooseVersion(sklearn.__version__)
from sklearn.covariance import ShrunkCovariance
except ImportError:
raise Exception('the scikit-learn package is missing and '
'required for covariance regularization.')
if sklearn_version < '0.12':
skl_cov = ShrunkCovariance(shrinkage=self.reg,
store_precision=False)
else:
# init sklearn.covariance.ShrunkCovariance estimator
skl_cov = ShrunkCovariance(shrinkage=self.reg,
store_precision=False,
assume_centered=True)
elif isinstance(self.reg, str):
if self.reg == 'lws':
try:
from sklearn.covariance import LedoitWolf
except ImportError:
raise Exception('the scikit-learn package is missing '
'and required for regularization.')
# init sklearn.covariance.LedoitWolf estimator
skl_cov = LedoitWolf(store_precision=False,
assume_centered=True)
elif self.reg == 'oas':
try:
from sklearn.covariance import OAS
except ImportError:
raise Exception('the scikit-learn package is missing '
'and required for regularization.')
# init sklearn.covariance.OAS estimator
skl_cov = OAS(store_precision=False, assume_centered=True)
else:
raise ValueError("regularization parameter should be "
"of type str (got %s)." % type(self.reg))
else:
raise ValueError("regularization parameter should be "
"of type str (got %s)." % type(self.reg))
# compute regularized covariance using sklearn
cov_1 = skl_cov.fit(class_1.T).covariance_
cov_2 = skl_cov.fit(class_2.T).covariance_
# then fit on covariance
self._fit(cov_1, cov_2)
pick_filters = self.filters_[:self.n_components]
X = np.asarray([np.dot(pick_filters, e) for e in epochs_data])
# compute features (mean band power)
X = (X**2).mean(axis=-1)
# To standardize features
self.mean_ = X.mean(axis=0)
self.std_ = X.std(axis=0)
return self
def test_oas():
# Tests OAS module on a simple dataset.
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
oa = OAS(assume_centered=True)
oa.fit(X_centered)
shrinkage_ = oa.shrinkage_
score_ = oa.score(X_centered)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X_centered,
assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0:1]
oa = OAS(assume_centered=True)
oa.fit(X_1d)
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X_1d, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False, assume_centered=True)
oa.fit(X_centered)
assert_almost_equal(oa.score(X_centered), score_, 4)
assert(oa.precision_ is None)
# Same tests without assuming centered data--------------------------------
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X)
assert_almost_equal(oa.shrinkage_, shrinkage_, 4)
assert_almost_equal(oa.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS()
oa.fit(X_1d)
oa_cov_from_mle, oa_shrinkage_from_mle = oas(X_1d)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shrinkage_from_mle, oa.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), oa.covariance_, 4)
# test with one sample
# warning should be raised when using only 1 sample
X_1sample = np.arange(5).reshape(1, 5)
oa = OAS()
assert_warns(UserWarning, oa.fit, X_1sample)
assert_array_almost_equal(oa.covariance_,
np.zeros(shape=(5, 5), dtype=np.float64))
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X)
assert_almost_equal(oa.score(X), score_, 4)
assert(oa.precision_ is None)
def test_ledoit_wolf():
# Tests LedoitWolf module on a simple dataset.
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
lw = LedoitWolf(assume_centered=True)
lw.fit(X_centered)
shrinkage_ = lw.shrinkage_
score_ = lw.score(X_centered)
assert_almost_equal(ledoit_wolf_shrinkage(X_centered,
assume_centered=True),
shrinkage_)
assert_almost_equal(ledoit_wolf_shrinkage(X_centered, assume_centered=True,
block_size=6),
shrinkage_)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X_centered,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf(assume_centered=True)
lw.fit(X_1d)
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X_1d,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False, assume_centered=True)
lw.fit(X_centered)
assert_almost_equal(lw.score(X_centered), score_, 4)
assert(lw.precision_ is None)
# Same tests without assuming centered data
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X)
assert_almost_equal(lw.shrinkage_, shrinkage_, 4)
assert_almost_equal(lw.shrinkage_, ledoit_wolf_shrinkage(X))
assert_almost_equal(lw.shrinkage_, ledoit_wolf(X)[1])
assert_almost_equal(lw.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d)
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X_1d)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), lw.covariance_, 4)
# test with one sample
# warning should be raised when using only 1 sample
X_1sample = np.arange(5).reshape(1, 5)
lw = LedoitWolf()
assert_warns(UserWarning, lw.fit, X_1sample)
assert_array_almost_equal(lw.covariance_,
np.zeros(shape=(5, 5), dtype=np.float64))
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X)
assert_almost_equal(lw.score(X), score_, 4)
assert(lw.precision_ is None)
def fit(self, epochs_data, y):
"""Estimate the CSP decomposition on epochs.
Parameters
----------
epochs_data : array, shape=(n_epochs, n_channels, n_times)
The data to estimate the CSP on.
y : array
The class for each epoch.
Returns
-------
self : instance of CSP
Returns the modified instance.
"""
if not isinstance(epochs_data, np.ndarray):
raise ValueError("epochs_data should be of type ndarray (got %s)."
% type(epochs_data))
epochs_data = np.atleast_3d(epochs_data)
classes = np.unique(y)
if len(classes) != 2:
raise ValueError("More than two different classes in the data.")
# concatenate epochs
class_1 = np.transpose(epochs_data[y == classes[0]],
[1, 0, 2]).reshape(epochs_data.shape[1], -1)
class_2 = np.transpose(epochs_data[y == classes[1]],
[1, 0, 2]).reshape(epochs_data.shape[1], -1)
if self.reg is None:
# compute empirical covariance
cov_1 = np.dot(class_1, class_1.T)
cov_2 = np.dot(class_2, class_2.T)
else:
# use sklearn covariance estimators
if isinstance(self.reg, float):
if (self.reg < 0) or (self.reg > 1):
raise ValueError('0 <= shrinkage <= 1 for '
'covariance regularization.')
try:
import sklearn
sklearn_version = LooseVersion(sklearn.__version__)
from sklearn.covariance import ShrunkCovariance
except ImportError:
raise Exception('the scikit-learn package is missing and '
'required for covariance regularization.')
if sklearn_version < '0.12':
skl_cov = ShrunkCovariance(shrinkage=self.reg,
store_precision=False)
else:
# init sklearn.covariance.ShrunkCovariance estimator
skl_cov = ShrunkCovariance(shrinkage=self.reg,
store_precision=False,
assume_centered=True)
elif isinstance(self.reg, str):
if self.reg == 'lws':
try:
from sklearn.covariance import LedoitWolf
except ImportError:
raise Exception('the scikit-learn package is missing '
'and required for regularization.')
# init sklearn.covariance.LedoitWolf estimator
skl_cov = LedoitWolf(store_precision=False,
assume_centered=True)
elif self.reg == 'oas':
try:
from sklearn.covariance import OAS
except ImportError:
raise Exception('the scikit-learn package is missing '
'and required for regularization.')
# init sklearn.covariance.OAS estimator
skl_cov = OAS(store_precision=False,
assume_centered=True)
else:
raise ValueError("regularization parameter should be "
"of type str (got %s)." % type(self.reg))
else:
raise ValueError("regularization parameter should be "
"of type str (got %s)." % type(self.reg))
# compute regularized covariance using sklearn
cov_1 = skl_cov.fit(class_1.T).covariance_
cov_2 = skl_cov.fit(class_2.T).covariance_
# then fit on covariance
self._fit(cov_1, cov_2)
pick_filters = self.filters_[:self.n_components]
X = np.asarray([np.dot(pick_filters, e) for e in epochs_data])
# compute features (mean band power)
X = (X ** 2).mean(axis=-1)
# To standardize features
self.mean_ = X.mean(axis=0)
self.std_ = X.std(axis=0)
return self
class LCMV(BaseEstimator, TransformerMixin):
'''
LCMV Spatial beamformer.
Parameters
----------
template : 1D array (n_channels)
Spatial activation pattern of the component to extract.
shrinkage : str | float (default: 'oas')
Shrinkage parameter for the covariance matrix inversion. This can
either be speficied as a number between 0 and 1, or as a string
indicating which automated estimation method to use:
'none': No shrinkage: emperical covariance
'oas': Oracle approximation shrinkage
'lw': Ledoit-Wolf approximation shrinkage
center : bool (default: True)
Whether to remove the channel mean before applying the filter.
Attributes
----------
W_ : 2D array (1 x n_channels)
Row vector containing the filter weights.
'''
def __init__(self, template, shrinkage='oas', center=True):
self.template = template
self.template = np.asarray(template).flatten()[:, np.newaxis]
self.center = center
if center:
self.template -= self.template.mean()
if shrinkage == 'oas':
self.cov = OAS
elif shrinkage == 'lw':
self.cov = LedoitWolf
elif shrinkage == 'none':
self.cov = EmpiricalCovariance
elif type(shrinkage) == float or type(shrinkage) == int:
self.cov = ShrunkCovariance(shrinkage=shrinkage)
def fit(self, X, y=None):
"""Fit the beamformer to the data.
Parameters
----------
X : 3D array (n_channels, n_samples, n_trials)
The trials.
y : None
Unused.
"""
if self.center:
X = X - X.mean(axis=0)
# Concatenate trials
cont_eeg = np.transpose(X, [0, 2, 1]).reshape((X.shape[0], -1))
# Calculate spatial covariance matrix
c = self.cov.fit(cont_eeg.T)
sigma_x_i = c.precision_
# Compute spatial LCMV filter
self.W_ = sigma_x_i.dot(self.template)
# Noise normalization
self.W_ = self.W_.dot(
np.linalg.inv(
reduce(np.dot, [self.template.T, sigma_x_i, self.template])
)
)
return self
def transform(self, X):
"""Transform the data using the beamformer.
Parameters
----------
X : 3D array (n_channels, n_samples, n_trials)
The trials.
Returns
-------
X_trans : 3D array (1, n_samples, n_trials)
The transformed data.
"""
if self.center:
X = X - X.mean(axis=0)
n_channels = self.W_.shape[1]
n_samples = X.shape[1]
n_trials = X.shape[2]
X_trans = np.zeros((n_channels, n_samples, n_trials))
for i in range(n_trials):
X_trans[:, :, i] = np.dot(self.W_.T, X[:, :, i])
return X_trans
class SpatialBeamformer(SpatialFilter):
'''
LCMV Spatial beamformer.
Parameters
----------
template : 1D array (n_channels)
Spatial activation pattern of the component to extract.
shrinkage : str | float (default: 'oas')
Shrinkage parameter for the covariance matrix inversion. This can
either be speficied as a number between 0 and 1, or as a string
indicating which automated estimation method to use:
'none': No shrinkage: emperical covariance
'oas': Oracle approximation shrinkage
'lw': Ledoit-Wolf approximation shrinkage
center : bool (default: True)
Whether to remove the channel mean before applying the filter.
'''
def __init__(self, template, shrinkage='oas', center=True):
SpatialFilter.__init__(self, 1)
self.template = template
self.template = np.asarray(template).flatten()[:, np.newaxis]
self.center = center
if center:
self.template -= self.template.mean()
if shrinkage == 'oas':
self.cov = OAS
elif shrinkage == 'lw':
self.cov = LedoitWolf
elif shrinkage == 'none':
self.cov = EmpiricalCovariance
elif type(shrinkage) == float or type(shrinkage) == int:
self.cov = ShrunkCovariance(shrinkage=shrinkage)
def train_(self, d):
if self.center:
d = DataSet(d.data - d.data.mean(axis=0), default=d)
d = baseline(d)
# Calculate spatial covariance matrix
c = self.cov.fit(concatenate_trials(d).X)
sigma_x_i = c.precision_
# Compute spatial LCMV filter
self.W = sigma_x_i.dot(self.template)
# Noise normalization
self.W = self.W.dot(
np.linalg.inv(
reduce(np.dot, [self.template.T, sigma_x_i, self.template])
)
)
def apply_(self, d):
if self.center:
d = DataSet(d.data - d.data.mean(axis=0), default=d)
d = baseline(d)
return SpatialFilter.apply_(self, d)
def test_oas():
"""Tests OAS module on a simple dataset.
"""
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
oa = OAS(assume_centered=True)
oa.fit(X_centered)
shrinkage_ = oa.shrinkage_
score_ = oa.score(X_centered)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_centered,
assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS(assume_centered=True)
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal((X_1d**2).sum() / n_samples, oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False, assume_centered=True)
oa.fit(X_centered)
assert_almost_equal(oa.score(X_centered), score_, 4)
assert (oa.precision_ is None)
### Same tests without assuming centered data
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X)
assert_almost_equal(oa.shrinkage_, shrinkage_, 4)
assert_almost_equal(oa.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS()
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), oa.covariance_, 4)
# test with one sample
X_1sample = np.arange(5)
oa = OAS()
with warnings.catch_warnings(record=True):
oa.fit(X_1sample)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X)
assert_almost_equal(oa.score(X), score_, 4)
assert (oa.precision_ is None)
def test_oas():
"""Tests OAS module on a simple dataset.
"""
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X, assume_centered=True)
assert_almost_equal(oa.shrinkage_, 0.018740, 4)
assert_almost_equal(oa.score(X, assume_centered=True), -5.03605, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X, assume_centered=True)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS()
oa.fit(X_1d, assume_centered=True)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d, assume_centered=True)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X, assume_centered=True)
assert_almost_equal(oa.score(X, assume_centered=True), -5.03605, 4)
assert(oa.precision_ is None)
### Same tests without assuming centered data
# test shrinkage coeff on a simple data set
oa = OAS()
oa.fit(X)
assert_almost_equal(oa.shrinkage_, 0.020236, 4)
assert_almost_equal(oa.score(X), 2.079025, 4)
# compare shrunk covariance obtained from data and from MLE estimate
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
# compare estimates given by OAS and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=oa.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, oa.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
oa = OAS()
oa.fit(X_1d)
oa_cov_from_mle, oa_shinkrage_from_mle = oas(X_1d)
assert_array_almost_equal(oa_cov_from_mle, oa.covariance_, 4)
assert_almost_equal(oa_shinkrage_from_mle, oa.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), oa.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
oa = OAS(store_precision=False)
oa.fit(X)
assert_almost_equal(oa.score(X), 2.079025, 4)
assert(oa.precision_ is None)
class LCMV(BaseEstimator, TransformerMixin):
'''
LCMV Spatial beamformer.
Parameters
----------
template : 1D array (n_channels,)
Spatial activation pattern of the component to extract.
shrinkage : str | float (default: 'oas')
Shrinkage parameter for the covariance matrix inversion. This can
either be speficied as a number between 0 and 1, or as a string
indicating which automated estimation method to use:
'none': No shrinkage: emperical covariance
'oas': Oracle approximation shrinkage
'lw': Ledoit-Wolf approximation shrinkage
center : bool (default: True)
Whether to remove the channel mean before applying the filter.
WARNING: only set to False if the data has been pre-centered. Applying
the filter to un-centered data may result in inaccuracies.
cov_i : 2D array (n_channels, n_channels) | None
The inverse spatial covariance matrix of the data. Use this to avoid
re-computing it during fitting. When this parameter is set, the
shrinkage parameter is ignored.
Attributes
----------
W_ : 2D array (n_channels, 1)
Column vector containing the filter weights.
'''
def __init__(self, template, shrinkage='oas', center=True, cov_i=None):
self.template = np.asarray(template).ravel()[:, np.newaxis]
self.center = center
if center:
self.template -= self.template.mean()
if shrinkage == 'oas':
self.cov = OAS()
elif shrinkage == 'lw':
self.cov = LedoitWolf()
elif shrinkage == 'none':
self.cov = EmpiricalCovariance()
elif type(shrinkage) == float or type(shrinkage) == int:
self.cov = ShrunkCovariance(shrinkage=shrinkage)
else:
raise ValueError('Invalid value for shrinkage parameter.')
self.cov_i = cov_i
def fit(self, X, y=None):
"""Fit the beamformer to the data.
Parameters
----------
X : 3D array (n_trials, n_channels, n_samples)
The trials.
y : None
Unused.
"""
if self.center:
X = X - X.mean(axis=1, keepdims=True)
if self.cov_i is None:
# Concatenate trials into an (n_channels, n_samples) matrix
cont_eeg = np.transpose(X, [1, 0, 2]).reshape((X.shape[1], -1))
# Calculate spatial covariance matrix
c = self.cov.fit(cont_eeg.T)
sigma_x_i = c.precision_
else:
sigma_x_i = self.cov_i
# Compute spatial LCMV filter
self.W_ = sigma_x_i.dot(self.template)
# Noise normalization
self.W_ = self.W_.dot(
np.linalg.inv(
reduce(np.dot, [self.template.T, sigma_x_i, self.template])))
return self
def transform(self, X):
"""Transform the data using the beamformer.
Parameters
----------
X : 3D array (n_trials, n_channels, n_samples)
The trials.
Returns
-------
X_trans : 2D array (n_trials, n_samples)
The transformed data.
"""
if self.center:
X = X - X.mean(axis=1, keepdims=True)
n_trials, _, n_samples = X.shape
X_trans = np.zeros((n_trials, n_samples))
for i in range(n_trials):
X_trans[i, :] = np.dot(self.W_.T, X[i, :, :]).ravel()
return X_trans
def test_ledoit_wolf():
# Tests LedoitWolf module on a simple dataset.
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
lw = LedoitWolf(assume_centered=True)
lw.fit(X_centered)
shrinkage_ = lw.shrinkage_
score_ = lw.score(X_centered)
assert_almost_equal(
ledoit_wolf_shrinkage(X_centered, assume_centered=True), shrinkage_)
assert_almost_equal(
ledoit_wolf_shrinkage(X_centered, assume_centered=True, block_size=6),
shrinkage_)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_centered,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf(assume_centered=True)
lw.fit(X_1d)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal((X_1d**2).sum() / n_samples, lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False, assume_centered=True)
lw.fit(X_centered)
assert_almost_equal(lw.score(X_centered), score_, 4)
assert (lw.precision_ is None)
# (too) large data set
X_large = np.ones((20, 200))
assert_raises(MemoryError, ledoit_wolf, X_large, block_size=100)
# Same tests without assuming centered data
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X)
assert_almost_equal(lw.shrinkage_, shrinkage_, 4)
assert_almost_equal(lw.shrinkage_, ledoit_wolf_shrinkage(X))
assert_almost_equal(lw.shrinkage_, ledoit_wolf(X)[1])
assert_almost_equal(lw.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), lw.covariance_, 4)
# test with one sample
# FIXME I don't know what this test does
X_1sample = np.arange(5)
lw = LedoitWolf()
assert_warns(UserWarning, lw.fit, X_1sample)
assert_array_almost_equal(lw.covariance_,
np.zeros(shape=(5, 5), dtype=np.float64))
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X)
assert_almost_equal(lw.score(X), score_, 4)
assert (lw.precision_ is None)
def test_ledoit_wolf():
# Tests LedoitWolf module on a simple dataset.
# test shrinkage coeff on a simple data set
X_centered = X - X.mean(axis=0)
lw = LedoitWolf(assume_centered=True)
lw.fit(X_centered)
shrinkage_ = lw.shrinkage_
score_ = lw.score(X_centered)
assert_almost_equal(
ledoit_wolf_shrinkage(X_centered, assume_centered=True), shrinkage_)
assert_almost_equal(
ledoit_wolf_shrinkage(X_centered, assume_centered=True, block_size=6),
shrinkage_)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X_centered,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_, assume_centered=True)
scov.fit(X_centered)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf(assume_centered=True)
lw.fit(X_1d)
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X_1d,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
assert_array_almost_equal((X_1d**2).sum() / n_samples, lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False, assume_centered=True)
lw.fit(X_centered)
assert_almost_equal(lw.score(X_centered), score_, 4)
assert (lw.precision_ is None)
# Same tests without assuming centered data
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X)
assert_almost_equal(lw.shrinkage_, shrinkage_, 4)
assert_almost_equal(lw.shrinkage_, ledoit_wolf_shrinkage(X))
assert_almost_equal(lw.shrinkage_, ledoit_wolf(X)[1])
assert_almost_equal(lw.score(X), score_, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d)
lw_cov_from_mle, lw_shrinkage_from_mle = ledoit_wolf(X_1d)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shrinkage_from_mle, lw.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), lw.covariance_, 4)
# test with one sample
# warning should be raised when using only 1 sample
X_1sample = np.arange(5).reshape(1, 5)
lw = LedoitWolf()
warn_msg = (
"Only one sample available. You may want to reshape your data array")
with pytest.warns(UserWarning, match=warn_msg):
lw.fit(X_1sample)
assert_array_almost_equal(lw.covariance_,
np.zeros(shape=(5, 5), dtype=np.float64))
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X)
assert_almost_equal(lw.score(X), score_, 4)
assert (lw.precision_ is None)
def test_ledoit_wolf():
"""Tests LedoitWolf module on a simple dataset.
"""
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X, assume_centered=True)
assert_almost_equal(lw.shrinkage_, 0.00192, 4)
assert_almost_equal(lw.score(X, assume_centered=True), -2.89795, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X, assume_centered=True)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d, assume_centered=True)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d,
assume_centered=True)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal((X_1d ** 2).sum() / n_samples, lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X, assume_centered=True)
assert_almost_equal(lw.score(X, assume_centered=True), -2.89795, 4)
assert(lw.precision_ is None)
# Same tests without assuming centered data
# test shrinkage coeff on a simple data set
lw = LedoitWolf()
lw.fit(X)
assert_almost_equal(lw.shrinkage_, 0.007582, 4)
assert_almost_equal(lw.score(X), 2.243483, 4)
# compare shrunk covariance obtained from data and from MLE estimate
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
# compare estimates given by LW and ShrunkCovariance
scov = ShrunkCovariance(shrinkage=lw.shrinkage_)
scov.fit(X)
assert_array_almost_equal(scov.covariance_, lw.covariance_, 4)
# test with n_features = 1
X_1d = X[:, 0].reshape((-1, 1))
lw = LedoitWolf()
lw.fit(X_1d)
lw_cov_from_mle, lw_shinkrage_from_mle = ledoit_wolf(X_1d)
assert_array_almost_equal(lw_cov_from_mle, lw.covariance_, 4)
assert_almost_equal(lw_shinkrage_from_mle, lw.shrinkage_)
assert_array_almost_equal(empirical_covariance(X_1d), lw.covariance_, 4)
# test shrinkage coeff on a simple data set (without saving precision)
lw = LedoitWolf(store_precision=False)
lw.fit(X)
assert_almost_equal(lw.score(X), 2.2434839, 4)
assert(lw.precision_ is None)
class stLCMV(BaseEstimator, TransformerMixin):
'''
Spatio-temporal LCMV beamformer operating on a spatio-temporal template.
Parameters
----------
template : 2D array (n_channels, n_samples)
Spatio-temporal activation pattern of the component to extract.
shrinkage : str | float (default: 'oas')
Shrinkage parameter for the covariance matrix inversion. This can
either be speficied as a number between 0 and 1, or as a string
indicating which automated estimation method to use:
'none': No shrinkage: emperical covariance
'oas': Oracle approximation shrinkage
'lw': Ledoit-Wolf approximation shrinkage
center : bool (default: True)
Whether to remove the data mean before applying the filter.
WARNING: only set to False if the data has been pre-centered. Applying
the filter to un-centered data may result in inaccuracies.
cov_i : 2D array (n_channels, n_channels) | None
The inverse spatio-temporal covariance matrix of the data. Use this to
avoid re-computing it during fitting. When this parameter is set, the
shrinkage parameter is ignored.
Attributes
----------
W_ : 2D array (n_channels * n_samples, 1)
Column vector containing the filter weights.
'''
def __init__(self, template, shrinkage='oas', center=True, cov_i=None):
self.template = template
self.template = np.atleast_2d(template)
self.center = center
if center:
self.template -= np.mean(self.template)
if shrinkage == 'oas':
self.cov = OAS()
elif shrinkage == 'lw':
self.cov = LedoitWolf()
elif shrinkage == 'none':
self.cov = EmpiricalCovariance()
elif type(shrinkage) == float or type(shrinkage) == int:
self.cov = ShrunkCovariance(shrinkage=shrinkage)
else:
raise ValueError('Invalid value for shrinkage parameter.')
self.cov_i = cov_i
def _center(self, X):
data_mean = X.reshape(X.shape[0], -1).mean(axis=1)
return X - data_mean[:, np.newaxis, np.newaxis]
def fit(self, X, y=None):
"""Fit the beamformer to the data.
Parameters
----------
X : 3D array (n_trials, n_channels, n_samples)
The trials.
y : None
Unused.
"""
if self.center:
X = self._center(X)
n_trials, _, n_samples = X.shape
template = self.template[:, :n_samples]
if self.cov_i is None:
c = self.cov.fit(X.reshape(n_trials, -1))
sigma_x_i = c.precision_
else:
sigma_x_i = self.cov_i
template = self.template.ravel()[:, np.newaxis]
self.W_ = sigma_x_i.dot(template)
# Noise normalization
if self.center:
self.W_ = self.W_.dot(
np.linalg.inv(reduce(np.dot,
[template.T, sigma_x_i, template])))
return self
def transform(self, X):
"""Transform the data using the beamformer.
Parameters
----------
X : 3D array (n_trials, n_channels, n_samples)
The trials.
Returns
-------
X_trans : 3D array (n_trials, 1)
The transformed data.
"""
if self.center:
X = self._center(X)
n_trials = X.shape[0]
X_trans = X.reshape(n_trials, -1).dot(self.W_)
return X_trans
