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"""
The :mod:`sklearn.mixture` module implements mixture modeling algorithms.
"""
from ._gaussian_mixture import GaussianMixture
from ._bayesian_mixture import BayesianGaussianMixture
__all__ = ['GaussianMixture',
'BayesianGaussianMixture']

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"""Base class for mixture models."""
# Author: Wei Xue <xuewei4d@gmail.com>
# Modified by Thierry Guillemot <thierry.guillemot.work@gmail.com>
# License: BSD 3 clause
import warnings
from abc import ABCMeta, abstractmethod
from time import time
import numpy as np
from scipy.special import logsumexp
from .. import cluster
from ..base import BaseEstimator
from ..base import DensityMixin
from ..exceptions import ConvergenceWarning
from ..utils import check_array, check_random_state
from ..utils.validation import check_is_fitted
def _check_shape(param, param_shape, name):
"""Validate the shape of the input parameter 'param'.
Parameters
----------
param : array
param_shape : tuple
name : string
"""
param = np.array(param)
if param.shape != param_shape:
raise ValueError("The parameter '%s' should have the shape of %s, "
"but got %s" % (name, param_shape, param.shape))
def _check_X(X, n_components=None, n_features=None, ensure_min_samples=1):
"""Check the input data X.
Parameters
----------
X : array-like, shape (n_samples, n_features)
n_components : int
Returns
-------
X : array, shape (n_samples, n_features)
"""
X = check_array(X, dtype=[np.float64, np.float32],
ensure_min_samples=ensure_min_samples)
if n_components is not None and X.shape[0] < n_components:
raise ValueError('Expected n_samples >= n_components '
'but got n_components = %d, n_samples = %d'
% (n_components, X.shape[0]))
if n_features is not None and X.shape[1] != n_features:
raise ValueError("Expected the input data X have %d features, "
"but got %d features"
% (n_features, X.shape[1]))
return X
class BaseMixture(DensityMixin, BaseEstimator, metaclass=ABCMeta):
"""Base class for mixture models.
This abstract class specifies an interface for all mixture classes and
provides basic common methods for mixture models.
"""
def __init__(self, n_components, tol, reg_covar,
max_iter, n_init, init_params, random_state, warm_start,
verbose, verbose_interval):
self.n_components = n_components
self.tol = tol
self.reg_covar = reg_covar
self.max_iter = max_iter
self.n_init = n_init
self.init_params = init_params
self.random_state = random_state
self.warm_start = warm_start
self.verbose = verbose
self.verbose_interval = verbose_interval
def _check_initial_parameters(self, X):
"""Check values of the basic parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
"""
if self.n_components < 1:
raise ValueError("Invalid value for 'n_components': %d "
"Estimation requires at least one component"
% self.n_components)
if self.tol < 0.:
raise ValueError("Invalid value for 'tol': %.5f "
"Tolerance used by the EM must be non-negative"
% self.tol)
if self.n_init < 1:
raise ValueError("Invalid value for 'n_init': %d "
"Estimation requires at least one run"
% self.n_init)
if self.max_iter < 1:
raise ValueError("Invalid value for 'max_iter': %d "
"Estimation requires at least one iteration"
% self.max_iter)
if self.reg_covar < 0.:
raise ValueError("Invalid value for 'reg_covar': %.5f "
"regularization on covariance must be "
"non-negative"
% self.reg_covar)
# Check all the parameters values of the derived class
self._check_parameters(X)
@abstractmethod
def _check_parameters(self, X):
"""Check initial parameters of the derived class.
Parameters
----------
X : array-like, shape (n_samples, n_features)
"""
pass
def _initialize_parameters(self, X, random_state):
"""Initialize the model parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
random_state : RandomState
A random number generator instance that controls the random seed
used for the method chosen to initialize the parameters.
"""
n_samples, _ = X.shape
if self.init_params == 'kmeans':
resp = np.zeros((n_samples, self.n_components))
label = cluster.KMeans(n_clusters=self.n_components, n_init=1,
random_state=random_state).fit(X).labels_
resp[np.arange(n_samples), label] = 1
elif self.init_params == 'random':
resp = random_state.rand(n_samples, self.n_components)
resp /= resp.sum(axis=1)[:, np.newaxis]
else:
raise ValueError("Unimplemented initialization method '%s'"
% self.init_params)
self._initialize(X, resp)
@abstractmethod
def _initialize(self, X, resp):
"""Initialize the model parameters of the derived class.
Parameters
----------
X : array-like, shape (n_samples, n_features)
resp : array-like, shape (n_samples, n_components)
"""
pass
def fit(self, X, y=None):
"""Estimate model parameters with the EM algorithm.
The method fits the model ``n_init`` times and sets the parameters with
which the model has the largest likelihood or lower bound. Within each
trial, the method iterates between E-step and M-step for ``max_iter``
times until the change of likelihood or lower bound is less than
``tol``, otherwise, a ``ConvergenceWarning`` is raised.
If ``warm_start`` is ``True``, then ``n_init`` is ignored and a single
initialization is performed upon the first call. Upon consecutive
calls, training starts where it left off.
Parameters
----------
X : array-like, shape (n_samples, n_features)
List of n_features-dimensional data points. Each row
corresponds to a single data point.
Returns
-------
self
"""
self.fit_predict(X, y)
return self
def fit_predict(self, X, y=None):
"""Estimate model parameters using X and predict the labels for X.
The method fits the model n_init times and sets the parameters with
which the model has the largest likelihood or lower bound. Within each
trial, the method iterates between E-step and M-step for `max_iter`
times until the change of likelihood or lower bound is less than
`tol`, otherwise, a :class:`~sklearn.exceptions.ConvergenceWarning` is
raised. After fitting, it predicts the most probable label for the
input data points.
.. versionadded:: 0.20
Parameters
----------
X : array-like, shape (n_samples, n_features)
List of n_features-dimensional data points. Each row
corresponds to a single data point.
Returns
-------
labels : array, shape (n_samples,)
Component labels.
"""
X = _check_X(X, self.n_components, ensure_min_samples=2)
self._check_n_features(X, reset=True)
self._check_initial_parameters(X)
# if we enable warm_start, we will have a unique initialisation
do_init = not(self.warm_start and hasattr(self, 'converged_'))
n_init = self.n_init if do_init else 1
max_lower_bound = -np.infty
self.converged_ = False
random_state = check_random_state(self.random_state)
n_samples, _ = X.shape
for init in range(n_init):
self._print_verbose_msg_init_beg(init)
if do_init:
self._initialize_parameters(X, random_state)
lower_bound = (-np.infty if do_init else self.lower_bound_)
for n_iter in range(1, self.max_iter + 1):
prev_lower_bound = lower_bound
log_prob_norm, log_resp = self._e_step(X)
self._m_step(X, log_resp)
lower_bound = self._compute_lower_bound(
log_resp, log_prob_norm)
change = lower_bound - prev_lower_bound
self._print_verbose_msg_iter_end(n_iter, change)
if abs(change) < self.tol:
self.converged_ = True
break
self._print_verbose_msg_init_end(lower_bound)
if lower_bound > max_lower_bound:
max_lower_bound = lower_bound
best_params = self._get_parameters()
best_n_iter = n_iter
if not self.converged_:
warnings.warn('Initialization %d did not converge. '
'Try different init parameters, '
'or increase max_iter, tol '
'or check for degenerate data.'
% (init + 1), ConvergenceWarning)
self._set_parameters(best_params)
self.n_iter_ = best_n_iter
self.lower_bound_ = max_lower_bound
# Always do a final e-step to guarantee that the labels returned by
# fit_predict(X) are always consistent with fit(X).predict(X)
# for any value of max_iter and tol (and any random_state).
_, log_resp = self._e_step(X)
return log_resp.argmax(axis=1)
def _e_step(self, X):
"""E step.
Parameters
----------
X : array-like, shape (n_samples, n_features)
Returns
-------
log_prob_norm : float
Mean of the logarithms of the probabilities of each sample in X
log_responsibility : array, shape (n_samples, n_components)
Logarithm of the posterior probabilities (or responsibilities) of
the point of each sample in X.
"""
log_prob_norm, log_resp = self._estimate_log_prob_resp(X)
return np.mean(log_prob_norm), log_resp
@abstractmethod
def _m_step(self, X, log_resp):
"""M step.
Parameters
----------
X : array-like, shape (n_samples, n_features)
log_resp : array-like, shape (n_samples, n_components)
Logarithm of the posterior probabilities (or responsibilities) of
the point of each sample in X.
"""
pass
@abstractmethod
def _get_parameters(self):
pass
@abstractmethod
def _set_parameters(self, params):
pass
def score_samples(self, X):
"""Compute the weighted log probabilities for each sample.
Parameters
----------
X : array-like, shape (n_samples, n_features)
List of n_features-dimensional data points. Each row
corresponds to a single data point.
Returns
-------
log_prob : array, shape (n_samples,)
Log probabilities of each data point in X.
"""
check_is_fitted(self)
X = _check_X(X, None, self.means_.shape[1])
return logsumexp(self._estimate_weighted_log_prob(X), axis=1)
def score(self, X, y=None):
"""Compute the per-sample average log-likelihood of the given data X.
Parameters
----------
X : array-like, shape (n_samples, n_dimensions)
List of n_features-dimensional data points. Each row
corresponds to a single data point.
Returns
-------
log_likelihood : float
Log likelihood of the Gaussian mixture given X.
"""
return self.score_samples(X).mean()
def predict(self, X):
"""Predict the labels for the data samples in X using trained model.
Parameters
----------
X : array-like, shape (n_samples, n_features)
List of n_features-dimensional data points. Each row
corresponds to a single data point.
Returns
-------
labels : array, shape (n_samples,)
Component labels.
"""
check_is_fitted(self)
X = _check_X(X, None, self.means_.shape[1])
return self._estimate_weighted_log_prob(X).argmax(axis=1)
def predict_proba(self, X):
"""Predict posterior probability of each component given the data.
Parameters
----------
X : array-like, shape (n_samples, n_features)
List of n_features-dimensional data points. Each row
corresponds to a single data point.
Returns
-------
resp : array, shape (n_samples, n_components)
Returns the probability each Gaussian (state) in
the model given each sample.
"""
check_is_fitted(self)
X = _check_X(X, None, self.means_.shape[1])
_, log_resp = self._estimate_log_prob_resp(X)
return np.exp(log_resp)
def sample(self, n_samples=1):
"""Generate random samples from the fitted Gaussian distribution.
Parameters
----------
n_samples : int, optional
Number of samples to generate. Defaults to 1.
Returns
-------
X : array, shape (n_samples, n_features)
Randomly generated sample
y : array, shape (nsamples,)
Component labels
"""
check_is_fitted(self)
if n_samples < 1:
raise ValueError(
"Invalid value for 'n_samples': %d . The sampling requires at "
"least one sample." % (self.n_components))
_, n_features = self.means_.shape
rng = check_random_state(self.random_state)
n_samples_comp = rng.multinomial(n_samples, self.weights_)
if self.covariance_type == 'full':
X = np.vstack([
rng.multivariate_normal(mean, covariance, int(sample))
for (mean, covariance, sample) in zip(
self.means_, self.covariances_, n_samples_comp)])
elif self.covariance_type == "tied":
X = np.vstack([
rng.multivariate_normal(mean, self.covariances_, int(sample))
for (mean, sample) in zip(
self.means_, n_samples_comp)])
else:
X = np.vstack([
mean + rng.randn(sample, n_features) * np.sqrt(covariance)
for (mean, covariance, sample) in zip(
self.means_, self.covariances_, n_samples_comp)])
y = np.concatenate([np.full(sample, j, dtype=int)
for j, sample in enumerate(n_samples_comp)])
return (X, y)
def _estimate_weighted_log_prob(self, X):
"""Estimate the weighted log-probabilities, log P(X | Z) + log weights.
Parameters
----------
X : array-like, shape (n_samples, n_features)
Returns
-------
weighted_log_prob : array, shape (n_samples, n_component)
"""
return self._estimate_log_prob(X) + self._estimate_log_weights()
@abstractmethod
def _estimate_log_weights(self):
"""Estimate log-weights in EM algorithm, E[ log pi ] in VB algorithm.
Returns
-------
log_weight : array, shape (n_components, )
"""
pass
@abstractmethod
def _estimate_log_prob(self, X):
"""Estimate the log-probabilities log P(X | Z).
Compute the log-probabilities per each component for each sample.
Parameters
----------
X : array-like, shape (n_samples, n_features)
Returns
-------
log_prob : array, shape (n_samples, n_component)
"""
pass
def _estimate_log_prob_resp(self, X):
"""Estimate log probabilities and responsibilities for each sample.
Compute the log probabilities, weighted log probabilities per
component and responsibilities for each sample in X with respect to
the current state of the model.
Parameters
----------
X : array-like, shape (n_samples, n_features)
Returns
-------
log_prob_norm : array, shape (n_samples,)
log p(X)
log_responsibilities : array, shape (n_samples, n_components)
logarithm of the responsibilities
"""
weighted_log_prob = self._estimate_weighted_log_prob(X)
log_prob_norm = logsumexp(weighted_log_prob, axis=1)
with np.errstate(under='ignore'):
# ignore underflow
log_resp = weighted_log_prob - log_prob_norm[:, np.newaxis]
return log_prob_norm, log_resp
def _print_verbose_msg_init_beg(self, n_init):
"""Print verbose message on initialization."""
if self.verbose == 1:
print("Initialization %d" % n_init)
elif self.verbose >= 2:
print("Initialization %d" % n_init)
self._init_prev_time = time()
self._iter_prev_time = self._init_prev_time
def _print_verbose_msg_iter_end(self, n_iter, diff_ll):
"""Print verbose message on initialization."""
if n_iter % self.verbose_interval == 0:
if self.verbose == 1:
print(" Iteration %d" % n_iter)
elif self.verbose >= 2:
cur_time = time()
print(" Iteration %d\t time lapse %.5fs\t ll change %.5f" % (
n_iter, cur_time - self._iter_prev_time, diff_ll))
self._iter_prev_time = cur_time
def _print_verbose_msg_init_end(self, ll):
"""Print verbose message on the end of iteration."""
if self.verbose == 1:
print("Initialization converged: %s" % self.converged_)
elif self.verbose >= 2:
print("Initialization converged: %s\t time lapse %.5fs\t ll %.5f" %
(self.converged_, time() - self._init_prev_time, ll))

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"""Bayesian Gaussian Mixture Model."""
# Author: Wei Xue <xuewei4d@gmail.com>
# Thierry Guillemot <thierry.guillemot.work@gmail.com>
# License: BSD 3 clause
import math
import numpy as np
from scipy.special import betaln, digamma, gammaln
from ._base import BaseMixture, _check_shape
from ._gaussian_mixture import _check_precision_matrix
from ._gaussian_mixture import _check_precision_positivity
from ._gaussian_mixture import _compute_log_det_cholesky
from ._gaussian_mixture import _compute_precision_cholesky
from ._gaussian_mixture import _estimate_gaussian_parameters
from ._gaussian_mixture import _estimate_log_gaussian_prob
from ..utils import check_array
from ..utils.validation import _deprecate_positional_args
def _log_dirichlet_norm(dirichlet_concentration):
"""Compute the log of the Dirichlet distribution normalization term.
Parameters
----------
dirichlet_concentration : array-like, shape (n_samples,)
The parameters values of the Dirichlet distribution.
Returns
-------
log_dirichlet_norm : float
The log normalization of the Dirichlet distribution.
"""
return (gammaln(np.sum(dirichlet_concentration)) -
np.sum(gammaln(dirichlet_concentration)))
def _log_wishart_norm(degrees_of_freedom, log_det_precisions_chol, n_features):
"""Compute the log of the Wishart distribution normalization term.
Parameters
----------
degrees_of_freedom : array-like, shape (n_components,)
The number of degrees of freedom on the covariance Wishart
distributions.
log_det_precision_chol : array-like, shape (n_components,)
The determinant of the precision matrix for each component.
n_features : int
The number of features.
Return
------
log_wishart_norm : array-like, shape (n_components,)
The log normalization of the Wishart distribution.
"""
# To simplify the computation we have removed the np.log(np.pi) term
return -(degrees_of_freedom * log_det_precisions_chol +
degrees_of_freedom * n_features * .5 * math.log(2.) +
np.sum(gammaln(.5 * (degrees_of_freedom -
np.arange(n_features)[:, np.newaxis])), 0))
class BayesianGaussianMixture(BaseMixture):
"""Variational Bayesian estimation of a Gaussian mixture.
This class allows to infer an approximate posterior distribution over the
parameters of a Gaussian mixture distribution. The effective number of
components can be inferred from the data.
This class implements two types of prior for the weights distribution: a
finite mixture model with Dirichlet distribution and an infinite mixture
model with the Dirichlet Process. In practice Dirichlet Process inference
algorithm is approximated and uses a truncated distribution with a fixed
maximum number of components (called the Stick-breaking representation).
The number of components actually used almost always depends on the data.
.. versionadded:: 0.18
Read more in the :ref:`User Guide <bgmm>`.
Parameters
----------
n_components : int, defaults to 1.
The number of mixture components. Depending on the data and the value
of the `weight_concentration_prior` the model can decide to not use
all the components by setting some component `weights_` to values very
close to zero. The number of effective components is therefore smaller
than n_components.
covariance_type : {'full', 'tied', 'diag', 'spherical'}, defaults to 'full'
String describing the type of covariance parameters to use.
Must be one of::
'full' (each component has its own general covariance matrix),
'tied' (all components share the same general covariance matrix),
'diag' (each component has its own diagonal covariance matrix),
'spherical' (each component has its own single variance).
tol : float, defaults to 1e-3.
The convergence threshold. EM iterations will stop when the
lower bound average gain on the likelihood (of the training data with
respect to the model) is below this threshold.
reg_covar : float, defaults to 1e-6.
Non-negative regularization added to the diagonal of covariance.
Allows to assure that the covariance matrices are all positive.
max_iter : int, defaults to 100.
The number of EM iterations to perform.
n_init : int, defaults to 1.
The number of initializations to perform. The result with the highest
lower bound value on the likelihood is kept.
init_params : {'kmeans', 'random'}, defaults to 'kmeans'.
The method used to initialize the weights, the means and the
covariances.
Must be one of::
'kmeans' : responsibilities are initialized using kmeans.
'random' : responsibilities are initialized randomly.
weight_concentration_prior_type : str, defaults to 'dirichlet_process'.
String describing the type of the weight concentration prior.
Must be one of::
'dirichlet_process' (using the Stick-breaking representation),
'dirichlet_distribution' (can favor more uniform weights).
weight_concentration_prior : float | None, optional.
The dirichlet concentration of each component on the weight
distribution (Dirichlet). This is commonly called gamma in the
literature. The higher concentration puts more mass in
the center and will lead to more components being active, while a lower
concentration parameter will lead to more mass at the edge of the
mixture weights simplex. The value of the parameter must be greater
than 0. If it is None, it's set to ``1. / n_components``.
mean_precision_prior : float | None, optional.
The precision prior on the mean distribution (Gaussian).
Controls the extent of where means can be placed. Larger
values concentrate the cluster means around `mean_prior`.
The value of the parameter must be greater than 0.
If it is None, it is set to 1.
mean_prior : array-like, shape (n_features,), optional
The prior on the mean distribution (Gaussian).
If it is None, it is set to the mean of X.
degrees_of_freedom_prior : float | None, optional.
The prior of the number of degrees of freedom on the covariance
distributions (Wishart). If it is None, it's set to `n_features`.
covariance_prior : float or array-like, optional
The prior on the covariance distribution (Wishart).
If it is None, the emiprical covariance prior is initialized using the
covariance of X. The shape depends on `covariance_type`::
(n_features, n_features) if 'full',
(n_features, n_features) if 'tied',
(n_features) if 'diag',
float if 'spherical'
random_state : int, RandomState instance or None, optional (default=None)
Controls the random seed given to the method chosen to initialize the
parameters (see `init_params`).
In addition, it controls the generation of random samples from the
fitted distribution (see the method `sample`).
Pass an int for reproducible output across multiple function calls.
See :term:`Glossary <random_state>`.
warm_start : bool, default to False.
If 'warm_start' is True, the solution of the last fitting is used as
initialization for the next call of fit(). This can speed up
convergence when fit is called several times on similar problems.
See :term:`the Glossary <warm_start>`.
verbose : int, default to 0.
Enable verbose output. If 1 then it prints the current
initialization and each iteration step. If greater than 1 then
it prints also the log probability and the time needed
for each step.
verbose_interval : int, default to 10.
Number of iteration done before the next print.
Attributes
----------
weights_ : array-like, shape (n_components,)
The weights of each mixture components.
means_ : array-like, shape (n_components, n_features)
The mean of each mixture component.
covariances_ : array-like
The covariance of each mixture component.
The shape depends on `covariance_type`::
(n_components,) if 'spherical',
(n_features, n_features) if 'tied',
(n_components, n_features) if 'diag',
(n_components, n_features, n_features) if 'full'
precisions_ : array-like
The precision matrices for each component in the mixture. A precision
matrix is the inverse of a covariance matrix. A covariance matrix is
symmetric positive definite so the mixture of Gaussian can be
equivalently parameterized by the precision matrices. Storing the
precision matrices instead of the covariance matrices makes it more
efficient to compute the log-likelihood of new samples at test time.
The shape depends on ``covariance_type``::
(n_components,) if 'spherical',
(n_features, n_features) if 'tied',
(n_components, n_features) if 'diag',
(n_components, n_features, n_features) if 'full'
precisions_cholesky_ : array-like
The cholesky decomposition of the precision matrices of each mixture
component. A precision matrix is the inverse of a covariance matrix.
A covariance matrix is symmetric positive definite so the mixture of
Gaussian can be equivalently parameterized by the precision matrices.
Storing the precision matrices instead of the covariance matrices makes
it more efficient to compute the log-likelihood of new samples at test
time. The shape depends on ``covariance_type``::
(n_components,) if 'spherical',
(n_features, n_features) if 'tied',
(n_components, n_features) if 'diag',
(n_components, n_features, n_features) if 'full'
converged_ : bool
True when convergence was reached in fit(), False otherwise.
n_iter_ : int
Number of step used by the best fit of inference to reach the
convergence.
lower_bound_ : float
Lower bound value on the likelihood (of the training data with
respect to the model) of the best fit of inference.
weight_concentration_prior_ : tuple or float
The dirichlet concentration of each component on the weight
distribution (Dirichlet). The type depends on
``weight_concentration_prior_type``::
(float, float) if 'dirichlet_process' (Beta parameters),
float if 'dirichlet_distribution' (Dirichlet parameters).
The higher concentration puts more mass in
the center and will lead to more components being active, while a lower
concentration parameter will lead to more mass at the edge of the
simplex.
weight_concentration_ : array-like, shape (n_components,)
The dirichlet concentration of each component on the weight
distribution (Dirichlet).
mean_precision_prior_ : float
The precision prior on the mean distribution (Gaussian).
Controls the extent of where means can be placed.
Larger values concentrate the cluster means around `mean_prior`.
If mean_precision_prior is set to None, `mean_precision_prior_` is set
to 1.
mean_precision_ : array-like, shape (n_components,)
The precision of each components on the mean distribution (Gaussian).
mean_prior_ : array-like, shape (n_features,)
The prior on the mean distribution (Gaussian).
degrees_of_freedom_prior_ : float
The prior of the number of degrees of freedom on the covariance
distributions (Wishart).
degrees_of_freedom_ : array-like, shape (n_components,)
The number of degrees of freedom of each components in the model.
covariance_prior_ : float or array-like
The prior on the covariance distribution (Wishart).
The shape depends on `covariance_type`::
(n_features, n_features) if 'full',
(n_features, n_features) if 'tied',
(n_features) if 'diag',
float if 'spherical'
See Also
--------
GaussianMixture : Finite Gaussian mixture fit with EM.
References
----------
.. [1] `Bishop, Christopher M. (2006). "Pattern recognition and machine
learning". Vol. 4 No. 4. New York: Springer.
<https://www.springer.com/kr/book/9780387310732>`_
.. [2] `Hagai Attias. (2000). "A Variational Bayesian Framework for
Graphical Models". In Advances in Neural Information Processing
Systems 12.
<http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.36.2841&rep=rep1&type=pdf>`_
.. [3] `Blei, David M. and Michael I. Jordan. (2006). "Variational
inference for Dirichlet process mixtures". Bayesian analysis 1.1
<https://www.cs.princeton.edu/courses/archive/fall11/cos597C/reading/BleiJordan2005.pdf>`_
"""
@_deprecate_positional_args
def __init__(self, *, n_components=1, covariance_type='full', tol=1e-3,
reg_covar=1e-6, max_iter=100, n_init=1, init_params='kmeans',
weight_concentration_prior_type='dirichlet_process',
weight_concentration_prior=None,
mean_precision_prior=None, mean_prior=None,
degrees_of_freedom_prior=None, covariance_prior=None,
random_state=None, warm_start=False, verbose=0,
verbose_interval=10):
super().__init__(
n_components=n_components, tol=tol, reg_covar=reg_covar,
max_iter=max_iter, n_init=n_init, init_params=init_params,
random_state=random_state, warm_start=warm_start,
verbose=verbose, verbose_interval=verbose_interval)
self.covariance_type = covariance_type
self.weight_concentration_prior_type = weight_concentration_prior_type
self.weight_concentration_prior = weight_concentration_prior
self.mean_precision_prior = mean_precision_prior
self.mean_prior = mean_prior
self.degrees_of_freedom_prior = degrees_of_freedom_prior
self.covariance_prior = covariance_prior
def _check_parameters(self, X):
"""Check that the parameters are well defined.
Parameters
----------
X : array-like, shape (n_samples, n_features)
"""
if self.covariance_type not in ['spherical', 'tied', 'diag', 'full']:
raise ValueError("Invalid value for 'covariance_type': %s "
"'covariance_type' should be in "
"['spherical', 'tied', 'diag', 'full']"
% self.covariance_type)
if (self.weight_concentration_prior_type not in
['dirichlet_process', 'dirichlet_distribution']):
raise ValueError(
"Invalid value for 'weight_concentration_prior_type': %s "
"'weight_concentration_prior_type' should be in "
"['dirichlet_process', 'dirichlet_distribution']"
% self.weight_concentration_prior_type)
self._check_weights_parameters()
self._check_means_parameters(X)
self._check_precision_parameters(X)
self._checkcovariance_prior_parameter(X)
def _check_weights_parameters(self):
"""Check the parameter of the Dirichlet distribution."""
if self.weight_concentration_prior is None:
self.weight_concentration_prior_ = 1. / self.n_components
elif self.weight_concentration_prior > 0.:
self.weight_concentration_prior_ = (
self.weight_concentration_prior)
else:
raise ValueError("The parameter 'weight_concentration_prior' "
"should be greater than 0., but got %.3f."
% self.weight_concentration_prior)
def _check_means_parameters(self, X):
"""Check the parameters of the Gaussian distribution.
Parameters
----------
X : array-like, shape (n_samples, n_features)
"""
_, n_features = X.shape
if self.mean_precision_prior is None:
self.mean_precision_prior_ = 1.
elif self.mean_precision_prior > 0.:
self.mean_precision_prior_ = self.mean_precision_prior
else:
raise ValueError("The parameter 'mean_precision_prior' should be "
"greater than 0., but got %.3f."
% self.mean_precision_prior)
if self.mean_prior is None:
self.mean_prior_ = X.mean(axis=0)
else:
self.mean_prior_ = check_array(self.mean_prior,
dtype=[np.float64, np.float32],
ensure_2d=False)
_check_shape(self.mean_prior_, (n_features, ), 'means')
def _check_precision_parameters(self, X):
"""Check the prior parameters of the precision distribution.
Parameters
----------
X : array-like, shape (n_samples, n_features)
"""
_, n_features = X.shape
if self.degrees_of_freedom_prior is None:
self.degrees_of_freedom_prior_ = n_features
elif self.degrees_of_freedom_prior > n_features - 1.:
self.degrees_of_freedom_prior_ = self.degrees_of_freedom_prior
else:
raise ValueError("The parameter 'degrees_of_freedom_prior' "
"should be greater than %d, but got %.3f."
% (n_features - 1, self.degrees_of_freedom_prior))
def _checkcovariance_prior_parameter(self, X):
"""Check the `covariance_prior_`.
Parameters
----------
X : array-like, shape (n_samples, n_features)
"""
_, n_features = X.shape
if self.covariance_prior is None:
self.covariance_prior_ = {
'full': np.atleast_2d(np.cov(X.T)),
'tied': np.atleast_2d(np.cov(X.T)),
'diag': np.var(X, axis=0, ddof=1),
'spherical': np.var(X, axis=0, ddof=1).mean()
}[self.covariance_type]
elif self.covariance_type in ['full', 'tied']:
self.covariance_prior_ = check_array(
self.covariance_prior, dtype=[np.float64, np.float32],
ensure_2d=False)
_check_shape(self.covariance_prior_, (n_features, n_features),
'%s covariance_prior' % self.covariance_type)
_check_precision_matrix(self.covariance_prior_,
self.covariance_type)
elif self.covariance_type == 'diag':
self.covariance_prior_ = check_array(
self.covariance_prior, dtype=[np.float64, np.float32],
ensure_2d=False)
_check_shape(self.covariance_prior_, (n_features,),
'%s covariance_prior' % self.covariance_type)
_check_precision_positivity(self.covariance_prior_,
self.covariance_type)
# spherical case
elif self.covariance_prior > 0.:
self.covariance_prior_ = self.covariance_prior
else:
raise ValueError("The parameter 'spherical covariance_prior' "
"should be greater than 0., but got %.3f."
% self.covariance_prior)
def _initialize(self, X, resp):
"""Initialization of the mixture parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
resp : array-like, shape (n_samples, n_components)
"""
nk, xk, sk = _estimate_gaussian_parameters(X, resp, self.reg_covar,
self.covariance_type)
self._estimate_weights(nk)
self._estimate_means(nk, xk)
self._estimate_precisions(nk, xk, sk)
def _estimate_weights(self, nk):
"""Estimate the parameters of the Dirichlet distribution.
Parameters
----------
nk : array-like, shape (n_components,)
"""
if self.weight_concentration_prior_type == 'dirichlet_process':
# For dirichlet process weight_concentration will be a tuple
# containing the two parameters of the beta distribution
self.weight_concentration_ = (
1. + nk,
(self.weight_concentration_prior_ +
np.hstack((np.cumsum(nk[::-1])[-2::-1], 0))))
else:
# case Variationnal Gaussian mixture with dirichlet distribution
self.weight_concentration_ = self.weight_concentration_prior_ + nk
def _estimate_means(self, nk, xk):
"""Estimate the parameters of the Gaussian distribution.
Parameters
----------
nk : array-like, shape (n_components,)
xk : array-like, shape (n_components, n_features)
"""
self.mean_precision_ = self.mean_precision_prior_ + nk
self.means_ = ((self.mean_precision_prior_ * self.mean_prior_ +
nk[:, np.newaxis] * xk) /
self.mean_precision_[:, np.newaxis])
def _estimate_precisions(self, nk, xk, sk):
"""Estimate the precisions parameters of the precision distribution.
Parameters
----------
nk : array-like, shape (n_components,)
xk : array-like, shape (n_components, n_features)
sk : array-like
The shape depends of `covariance_type`:
'full' : (n_components, n_features, n_features)
'tied' : (n_features, n_features)
'diag' : (n_components, n_features)
'spherical' : (n_components,)
"""
{"full": self._estimate_wishart_full,
"tied": self._estimate_wishart_tied,
"diag": self._estimate_wishart_diag,
"spherical": self._estimate_wishart_spherical
}[self.covariance_type](nk, xk, sk)
self.precisions_cholesky_ = _compute_precision_cholesky(
self.covariances_, self.covariance_type)
def _estimate_wishart_full(self, nk, xk, sk):
"""Estimate the full Wishart distribution parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
xk : array-like, shape (n_components, n_features)
sk : array-like, shape (n_components, n_features, n_features)
"""
_, n_features = xk.shape
# Warning : in some Bishop book, there is a typo on the formula 10.63
# `degrees_of_freedom_k = degrees_of_freedom_0 + Nk` is
# the correct formula
self.degrees_of_freedom_ = self.degrees_of_freedom_prior_ + nk
self.covariances_ = np.empty((self.n_components, n_features,
n_features))
for k in range(self.n_components):
diff = xk[k] - self.mean_prior_
self.covariances_[k] = (self.covariance_prior_ + nk[k] * sk[k] +
nk[k] * self.mean_precision_prior_ /
self.mean_precision_[k] * np.outer(diff,
diff))
# Contrary to the original bishop book, we normalize the covariances
self.covariances_ /= (
self.degrees_of_freedom_[:, np.newaxis, np.newaxis])
def _estimate_wishart_tied(self, nk, xk, sk):
"""Estimate the tied Wishart distribution parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
xk : array-like, shape (n_components, n_features)
sk : array-like, shape (n_features, n_features)
"""
_, n_features = xk.shape
# Warning : in some Bishop book, there is a typo on the formula 10.63
# `degrees_of_freedom_k = degrees_of_freedom_0 + Nk`
# is the correct formula
self.degrees_of_freedom_ = (
self.degrees_of_freedom_prior_ + nk.sum() / self.n_components)
diff = xk - self.mean_prior_
self.covariances_ = (
self.covariance_prior_ + sk * nk.sum() / self.n_components +
self.mean_precision_prior_ / self.n_components * np.dot(
(nk / self.mean_precision_) * diff.T, diff))
# Contrary to the original bishop book, we normalize the covariances
self.covariances_ /= self.degrees_of_freedom_
def _estimate_wishart_diag(self, nk, xk, sk):
"""Estimate the diag Wishart distribution parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
xk : array-like, shape (n_components, n_features)
sk : array-like, shape (n_components, n_features)
"""
_, n_features = xk.shape
# Warning : in some Bishop book, there is a typo on the formula 10.63
# `degrees_of_freedom_k = degrees_of_freedom_0 + Nk`
# is the correct formula
self.degrees_of_freedom_ = self.degrees_of_freedom_prior_ + nk
diff = xk - self.mean_prior_
self.covariances_ = (
self.covariance_prior_ + nk[:, np.newaxis] * (
sk + (self.mean_precision_prior_ /
self.mean_precision_)[:, np.newaxis] * np.square(diff)))
# Contrary to the original bishop book, we normalize the covariances
self.covariances_ /= self.degrees_of_freedom_[:, np.newaxis]
def _estimate_wishart_spherical(self, nk, xk, sk):
"""Estimate the spherical Wishart distribution parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
xk : array-like, shape (n_components, n_features)
sk : array-like, shape (n_components,)
"""
_, n_features = xk.shape
# Warning : in some Bishop book, there is a typo on the formula 10.63
# `degrees_of_freedom_k = degrees_of_freedom_0 + Nk`
# is the correct formula
self.degrees_of_freedom_ = self.degrees_of_freedom_prior_ + nk
diff = xk - self.mean_prior_
self.covariances_ = (
self.covariance_prior_ + nk * (
sk + self.mean_precision_prior_ / self.mean_precision_ *
np.mean(np.square(diff), 1)))
# Contrary to the original bishop book, we normalize the covariances
self.covariances_ /= self.degrees_of_freedom_
def _m_step(self, X, log_resp):
"""M step.
Parameters
----------
X : array-like, shape (n_samples, n_features)
log_resp : array-like, shape (n_samples, n_components)
Logarithm of the posterior probabilities (or responsibilities) of
the point of each sample in X.
"""
n_samples, _ = X.shape
nk, xk, sk = _estimate_gaussian_parameters(
X, np.exp(log_resp), self.reg_covar, self.covariance_type)
self._estimate_weights(nk)
self._estimate_means(nk, xk)
self._estimate_precisions(nk, xk, sk)
def _estimate_log_weights(self):
if self.weight_concentration_prior_type == 'dirichlet_process':
digamma_sum = digamma(self.weight_concentration_[0] +
self.weight_concentration_[1])
digamma_a = digamma(self.weight_concentration_[0])
digamma_b = digamma(self.weight_concentration_[1])
return (digamma_a - digamma_sum +
np.hstack((0, np.cumsum(digamma_b - digamma_sum)[:-1])))
else:
# case Variationnal Gaussian mixture with dirichlet distribution
return (digamma(self.weight_concentration_) -
digamma(np.sum(self.weight_concentration_)))
def _estimate_log_prob(self, X):
_, n_features = X.shape
# We remove `n_features * np.log(self.degrees_of_freedom_)` because
# the precision matrix is normalized
log_gauss = (_estimate_log_gaussian_prob(
X, self.means_, self.precisions_cholesky_, self.covariance_type) -
.5 * n_features * np.log(self.degrees_of_freedom_))
log_lambda = n_features * np.log(2.) + np.sum(digamma(
.5 * (self.degrees_of_freedom_ -
np.arange(0, n_features)[:, np.newaxis])), 0)
return log_gauss + .5 * (log_lambda -
n_features / self.mean_precision_)
def _compute_lower_bound(self, log_resp, log_prob_norm):
"""Estimate the lower bound of the model.
The lower bound on the likelihood (of the training data with respect to
the model) is used to detect the convergence and has to decrease at
each iteration.
Parameters
----------
X : array-like, shape (n_samples, n_features)
log_resp : array, shape (n_samples, n_components)
Logarithm of the posterior probabilities (or responsibilities) of
the point of each sample in X.
log_prob_norm : float
Logarithm of the probability of each sample in X.
Returns
-------
lower_bound : float
"""
# Contrary to the original formula, we have done some simplification
# and removed all the constant terms.
n_features, = self.mean_prior_.shape
# We removed `.5 * n_features * np.log(self.degrees_of_freedom_)`
# because the precision matrix is normalized.
log_det_precisions_chol = (_compute_log_det_cholesky(
self.precisions_cholesky_, self.covariance_type, n_features) -
.5 * n_features * np.log(self.degrees_of_freedom_))
if self.covariance_type == 'tied':
log_wishart = self.n_components * np.float64(_log_wishart_norm(
self.degrees_of_freedom_, log_det_precisions_chol, n_features))
else:
log_wishart = np.sum(_log_wishart_norm(
self.degrees_of_freedom_, log_det_precisions_chol, n_features))
if self.weight_concentration_prior_type == 'dirichlet_process':
log_norm_weight = -np.sum(betaln(self.weight_concentration_[0],
self.weight_concentration_[1]))
else:
log_norm_weight = _log_dirichlet_norm(self.weight_concentration_)
return (-np.sum(np.exp(log_resp) * log_resp) -
log_wishart - log_norm_weight -
0.5 * n_features * np.sum(np.log(self.mean_precision_)))
def _get_parameters(self):
return (self.weight_concentration_,
self.mean_precision_, self.means_,
self.degrees_of_freedom_, self.covariances_,
self.precisions_cholesky_)
def _set_parameters(self, params):
(self.weight_concentration_, self.mean_precision_, self.means_,
self.degrees_of_freedom_, self.covariances_,
self.precisions_cholesky_) = params
# Weights computation
if self.weight_concentration_prior_type == "dirichlet_process":
weight_dirichlet_sum = (self.weight_concentration_[0] +
self.weight_concentration_[1])
tmp = self.weight_concentration_[1] / weight_dirichlet_sum
self.weights_ = (
self.weight_concentration_[0] / weight_dirichlet_sum *
np.hstack((1, np.cumprod(tmp[:-1]))))
self.weights_ /= np.sum(self.weights_)
else:
self. weights_ = (self.weight_concentration_ /
np.sum(self.weight_concentration_))
# Precisions matrices computation
if self.covariance_type == 'full':
self.precisions_ = np.array([
np.dot(prec_chol, prec_chol.T)
for prec_chol in self.precisions_cholesky_])
elif self.covariance_type == 'tied':
self.precisions_ = np.dot(self.precisions_cholesky_,
self.precisions_cholesky_.T)
else:
self.precisions_ = self.precisions_cholesky_ ** 2

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@ -0,0 +1,754 @@
"""Gaussian Mixture Model."""
# Author: Wei Xue <xuewei4d@gmail.com>
# Modified by Thierry Guillemot <thierry.guillemot.work@gmail.com>
# License: BSD 3 clause
import numpy as np
from scipy import linalg
from ._base import BaseMixture, _check_shape
from ..utils import check_array
from ..utils.extmath import row_norms
from ..utils.validation import _deprecate_positional_args
###############################################################################
# Gaussian mixture shape checkers used by the GaussianMixture class
def _check_weights(weights, n_components):
"""Check the user provided 'weights'.
Parameters
----------
weights : array-like, shape (n_components,)
The proportions of components of each mixture.
n_components : int
Number of components.
Returns
-------
weights : array, shape (n_components,)
"""
weights = check_array(weights, dtype=[np.float64, np.float32],
ensure_2d=False)
_check_shape(weights, (n_components,), 'weights')
# check range
if (any(np.less(weights, 0.)) or
any(np.greater(weights, 1.))):
raise ValueError("The parameter 'weights' should be in the range "
"[0, 1], but got max value %.5f, min value %.5f"
% (np.min(weights), np.max(weights)))
# check normalization
if not np.allclose(np.abs(1. - np.sum(weights)), 0.):
raise ValueError("The parameter 'weights' should be normalized, "
"but got sum(weights) = %.5f" % np.sum(weights))
return weights
def _check_means(means, n_components, n_features):
"""Validate the provided 'means'.
Parameters
----------
means : array-like, shape (n_components, n_features)
The centers of the current components.
n_components : int
Number of components.
n_features : int
Number of features.
Returns
-------
means : array, (n_components, n_features)
"""
means = check_array(means, dtype=[np.float64, np.float32], ensure_2d=False)
_check_shape(means, (n_components, n_features), 'means')
return means
def _check_precision_positivity(precision, covariance_type):
"""Check a precision vector is positive-definite."""
if np.any(np.less_equal(precision, 0.0)):
raise ValueError("'%s precision' should be "
"positive" % covariance_type)
def _check_precision_matrix(precision, covariance_type):
"""Check a precision matrix is symmetric and positive-definite."""
if not (np.allclose(precision, precision.T) and
np.all(linalg.eigvalsh(precision) > 0.)):
raise ValueError("'%s precision' should be symmetric, "
"positive-definite" % covariance_type)
def _check_precisions_full(precisions, covariance_type):
"""Check the precision matrices are symmetric and positive-definite."""
for prec in precisions:
_check_precision_matrix(prec, covariance_type)
def _check_precisions(precisions, covariance_type, n_components, n_features):
"""Validate user provided precisions.
Parameters
----------
precisions : array-like
'full' : shape of (n_components, n_features, n_features)
'tied' : shape of (n_features, n_features)
'diag' : shape of (n_components, n_features)
'spherical' : shape of (n_components,)
covariance_type : string
n_components : int
Number of components.
n_features : int
Number of features.
Returns
-------
precisions : array
"""
precisions = check_array(precisions, dtype=[np.float64, np.float32],
ensure_2d=False,
allow_nd=covariance_type == 'full')
precisions_shape = {'full': (n_components, n_features, n_features),
'tied': (n_features, n_features),
'diag': (n_components, n_features),
'spherical': (n_components,)}
_check_shape(precisions, precisions_shape[covariance_type],
'%s precision' % covariance_type)
_check_precisions = {'full': _check_precisions_full,
'tied': _check_precision_matrix,
'diag': _check_precision_positivity,
'spherical': _check_precision_positivity}
_check_precisions[covariance_type](precisions, covariance_type)
return precisions
###############################################################################
# Gaussian mixture parameters estimators (used by the M-Step)
def _estimate_gaussian_covariances_full(resp, X, nk, means, reg_covar):
"""Estimate the full covariance matrices.
Parameters
----------
resp : array-like, shape (n_samples, n_components)
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
means : array-like, shape (n_components, n_features)
reg_covar : float
Returns
-------
covariances : array, shape (n_components, n_features, n_features)
The covariance matrix of the current components.
"""
n_components, n_features = means.shape
covariances = np.empty((n_components, n_features, n_features))
for k in range(n_components):
diff = X - means[k]
covariances[k] = np.dot(resp[:, k] * diff.T, diff) / nk[k]
covariances[k].flat[::n_features + 1] += reg_covar
return covariances
def _estimate_gaussian_covariances_tied(resp, X, nk, means, reg_covar):
"""Estimate the tied covariance matrix.
Parameters
----------
resp : array-like, shape (n_samples, n_components)
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
means : array-like, shape (n_components, n_features)
reg_covar : float
Returns
-------
covariance : array, shape (n_features, n_features)
The tied covariance matrix of the components.
"""
avg_X2 = np.dot(X.T, X)
avg_means2 = np.dot(nk * means.T, means)
covariance = avg_X2 - avg_means2
covariance /= nk.sum()
covariance.flat[::len(covariance) + 1] += reg_covar
return covariance
def _estimate_gaussian_covariances_diag(resp, X, nk, means, reg_covar):
"""Estimate the diagonal covariance vectors.
Parameters
----------
responsibilities : array-like, shape (n_samples, n_components)
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
means : array-like, shape (n_components, n_features)
reg_covar : float
Returns
-------
covariances : array, shape (n_components, n_features)
The covariance vector of the current components.
"""
avg_X2 = np.dot(resp.T, X * X) / nk[:, np.newaxis]
avg_means2 = means ** 2
avg_X_means = means * np.dot(resp.T, X) / nk[:, np.newaxis]
return avg_X2 - 2 * avg_X_means + avg_means2 + reg_covar
def _estimate_gaussian_covariances_spherical(resp, X, nk, means, reg_covar):
"""Estimate the spherical variance values.
Parameters
----------
responsibilities : array-like, shape (n_samples, n_components)
X : array-like, shape (n_samples, n_features)
nk : array-like, shape (n_components,)
means : array-like, shape (n_components, n_features)
reg_covar : float
Returns
-------
variances : array, shape (n_components,)
The variance values of each components.
"""
return _estimate_gaussian_covariances_diag(resp, X, nk,
means, reg_covar).mean(1)
def _estimate_gaussian_parameters(X, resp, reg_covar, covariance_type):
"""Estimate the Gaussian distribution parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
The input data array.
resp : array-like, shape (n_samples, n_components)
The responsibilities for each data sample in X.
reg_covar : float
The regularization added to the diagonal of the covariance matrices.
covariance_type : {'full', 'tied', 'diag', 'spherical'}
The type of precision matrices.
Returns
-------
nk : array-like, shape (n_components,)
The numbers of data samples in the current components.
means : array-like, shape (n_components, n_features)
The centers of the current components.
covariances : array-like
The covariance matrix of the current components.
The shape depends of the covariance_type.
"""
nk = resp.sum(axis=0) + 10 * np.finfo(resp.dtype).eps
means = np.dot(resp.T, X) / nk[:, np.newaxis]
covariances = {"full": _estimate_gaussian_covariances_full,
"tied": _estimate_gaussian_covariances_tied,
"diag": _estimate_gaussian_covariances_diag,
"spherical": _estimate_gaussian_covariances_spherical
}[covariance_type](resp, X, nk, means, reg_covar)
return nk, means, covariances
def _compute_precision_cholesky(covariances, covariance_type):
"""Compute the Cholesky decomposition of the precisions.
Parameters
----------
covariances : array-like
The covariance matrix of the current components.
The shape depends of the covariance_type.
covariance_type : {'full', 'tied', 'diag', 'spherical'}
The type of precision matrices.
Returns
-------
precisions_cholesky : array-like
The cholesky decomposition of sample precisions of the current
components. The shape depends of the covariance_type.
"""
estimate_precision_error_message = (
"Fitting the mixture model failed because some components have "
"ill-defined empirical covariance (for instance caused by singleton "
"or collapsed samples). Try to decrease the number of components, "
"or increase reg_covar.")
if covariance_type == 'full':
n_components, n_features, _ = covariances.shape
precisions_chol = np.empty((n_components, n_features, n_features))
for k, covariance in enumerate(covariances):
try:
cov_chol = linalg.cholesky(covariance, lower=True)
except linalg.LinAlgError:
raise ValueError(estimate_precision_error_message)
precisions_chol[k] = linalg.solve_triangular(cov_chol,
np.eye(n_features),
lower=True).T
elif covariance_type == 'tied':
_, n_features = covariances.shape
try:
cov_chol = linalg.cholesky(covariances, lower=True)
except linalg.LinAlgError:
raise ValueError(estimate_precision_error_message)
precisions_chol = linalg.solve_triangular(cov_chol, np.eye(n_features),
lower=True).T
else:
if np.any(np.less_equal(covariances, 0.0)):
raise ValueError(estimate_precision_error_message)
precisions_chol = 1. / np.sqrt(covariances)
return precisions_chol
###############################################################################
# Gaussian mixture probability estimators
def _compute_log_det_cholesky(matrix_chol, covariance_type, n_features):
"""Compute the log-det of the cholesky decomposition of matrices.
Parameters
----------
matrix_chol : array-like
Cholesky decompositions of the matrices.
'full' : shape of (n_components, n_features, n_features)
'tied' : shape of (n_features, n_features)
'diag' : shape of (n_components, n_features)
'spherical' : shape of (n_components,)
covariance_type : {'full', 'tied', 'diag', 'spherical'}
n_features : int
Number of features.
Returns
-------
log_det_precision_chol : array-like, shape (n_components,)
The determinant of the precision matrix for each component.
"""
if covariance_type == 'full':
n_components, _, _ = matrix_chol.shape
log_det_chol = (np.sum(np.log(
matrix_chol.reshape(
n_components, -1)[:, ::n_features + 1]), 1))
elif covariance_type == 'tied':
log_det_chol = (np.sum(np.log(np.diag(matrix_chol))))
elif covariance_type == 'diag':
log_det_chol = (np.sum(np.log(matrix_chol), axis=1))
else:
log_det_chol = n_features * (np.log(matrix_chol))
return log_det_chol
def _estimate_log_gaussian_prob(X, means, precisions_chol, covariance_type):
"""Estimate the log Gaussian probability.
Parameters
----------
X : array-like, shape (n_samples, n_features)
means : array-like, shape (n_components, n_features)
precisions_chol : array-like
Cholesky decompositions of the precision matrices.
'full' : shape of (n_components, n_features, n_features)
'tied' : shape of (n_features, n_features)
'diag' : shape of (n_components, n_features)
'spherical' : shape of (n_components,)
covariance_type : {'full', 'tied', 'diag', 'spherical'}
Returns
-------
log_prob : array, shape (n_samples, n_components)
"""
n_samples, n_features = X.shape
n_components, _ = means.shape
# det(precision_chol) is half of det(precision)
log_det = _compute_log_det_cholesky(
precisions_chol, covariance_type, n_features)
if covariance_type == 'full':
log_prob = np.empty((n_samples, n_components))
for k, (mu, prec_chol) in enumerate(zip(means, precisions_chol)):
y = np.dot(X, prec_chol) - np.dot(mu, prec_chol)
log_prob[:, k] = np.sum(np.square(y), axis=1)
elif covariance_type == 'tied':
log_prob = np.empty((n_samples, n_components))
for k, mu in enumerate(means):
y = np.dot(X, precisions_chol) - np.dot(mu, precisions_chol)
log_prob[:, k] = np.sum(np.square(y), axis=1)
elif covariance_type == 'diag':
precisions = precisions_chol ** 2
log_prob = (np.sum((means ** 2 * precisions), 1) -
2. * np.dot(X, (means * precisions).T) +
np.dot(X ** 2, precisions.T))
elif covariance_type == 'spherical':
precisions = precisions_chol ** 2
log_prob = (np.sum(means ** 2, 1) * precisions -
2 * np.dot(X, means.T * precisions) +
np.outer(row_norms(X, squared=True), precisions))
return -.5 * (n_features * np.log(2 * np.pi) + log_prob) + log_det
class GaussianMixture(BaseMixture):
"""Gaussian Mixture.
Representation of a Gaussian mixture model probability distribution.
This class allows to estimate the parameters of a Gaussian mixture
distribution.
Read more in the :ref:`User Guide <gmm>`.
.. versionadded:: 0.18
Parameters
----------
n_components : int, defaults to 1.
The number of mixture components.
covariance_type : {'full' (default), 'tied', 'diag', 'spherical'}
String describing the type of covariance parameters to use.
Must be one of:
'full'
each component has its own general covariance matrix
'tied'
all components share the same general covariance matrix
'diag'
each component has its own diagonal covariance matrix
'spherical'
each component has its own single variance
tol : float, defaults to 1e-3.
The convergence threshold. EM iterations will stop when the
lower bound average gain is below this threshold.
reg_covar : float, defaults to 1e-6.
Non-negative regularization added to the diagonal of covariance.
Allows to assure that the covariance matrices are all positive.
max_iter : int, defaults to 100.
The number of EM iterations to perform.
n_init : int, defaults to 1.
The number of initializations to perform. The best results are kept.
init_params : {'kmeans', 'random'}, defaults to 'kmeans'.
The method used to initialize the weights, the means and the
precisions.
Must be one of::
'kmeans' : responsibilities are initialized using kmeans.
'random' : responsibilities are initialized randomly.
weights_init : array-like, shape (n_components, ), optional
The user-provided initial weights, defaults to None.
If it None, weights are initialized using the `init_params` method.
means_init : array-like, shape (n_components, n_features), optional
The user-provided initial means, defaults to None,
If it None, means are initialized using the `init_params` method.
precisions_init : array-like, optional.
The user-provided initial precisions (inverse of the covariance
matrices), defaults to None.
If it None, precisions are initialized using the 'init_params' method.
The shape depends on 'covariance_type'::
(n_components,) if 'spherical',
(n_features, n_features) if 'tied',
(n_components, n_features) if 'diag',
(n_components, n_features, n_features) if 'full'
random_state : int, RandomState instance or None, optional (default=None)
Controls the random seed given to the method chosen to initialize the
parameters (see `init_params`).
In addition, it controls the generation of random samples from the
fitted distribution (see the method `sample`).
Pass an int for reproducible output across multiple function calls.
See :term:`Glossary <random_state>`.
warm_start : bool, default to False.
If 'warm_start' is True, the solution of the last fitting is used as
initialization for the next call of fit(). This can speed up
convergence when fit is called several times on similar problems.
In that case, 'n_init' is ignored and only a single initialization
occurs upon the first call.
See :term:`the Glossary <warm_start>`.
verbose : int, default to 0.
Enable verbose output. If 1 then it prints the current
initialization and each iteration step. If greater than 1 then
it prints also the log probability and the time needed
for each step.
verbose_interval : int, default to 10.
Number of iteration done before the next print.
Attributes
----------
weights_ : array-like, shape (n_components,)
The weights of each mixture components.
means_ : array-like, shape (n_components, n_features)
The mean of each mixture component.
covariances_ : array-like
The covariance of each mixture component.
The shape depends on `covariance_type`::
(n_components,) if 'spherical',
(n_features, n_features) if 'tied',
(n_components, n_features) if 'diag',
(n_components, n_features, n_features) if 'full'
precisions_ : array-like
The precision matrices for each component in the mixture. A precision
matrix is the inverse of a covariance matrix. A covariance matrix is
symmetric positive definite so the mixture of Gaussian can be
equivalently parameterized by the precision matrices. Storing the
precision matrices instead of the covariance matrices makes it more
efficient to compute the log-likelihood of new samples at test time.
The shape depends on `covariance_type`::
(n_components,) if 'spherical',
(n_features, n_features) if 'tied',
(n_components, n_features) if 'diag',
(n_components, n_features, n_features) if 'full'
precisions_cholesky_ : array-like
The cholesky decomposition of the precision matrices of each mixture
component. A precision matrix is the inverse of a covariance matrix.
A covariance matrix is symmetric positive definite so the mixture of
Gaussian can be equivalently parameterized by the precision matrices.
Storing the precision matrices instead of the covariance matrices makes
it more efficient to compute the log-likelihood of new samples at test
time. The shape depends on `covariance_type`::
(n_components,) if 'spherical',
(n_features, n_features) if 'tied',
(n_components, n_features) if 'diag',
(n_components, n_features, n_features) if 'full'
converged_ : bool
True when convergence was reached in fit(), False otherwise.
n_iter_ : int
Number of step used by the best fit of EM to reach the convergence.
lower_bound_ : float
Lower bound value on the log-likelihood (of the training data with
respect to the model) of the best fit of EM.
See Also
--------
BayesianGaussianMixture : Gaussian mixture model fit with a variational
inference.
"""
@_deprecate_positional_args
def __init__(self, n_components=1, *, covariance_type='full', tol=1e-3,
reg_covar=1e-6, max_iter=100, n_init=1, init_params='kmeans',
weights_init=None, means_init=None, precisions_init=None,
random_state=None, warm_start=False,
verbose=0, verbose_interval=10):
super().__init__(
n_components=n_components, tol=tol, reg_covar=reg_covar,
max_iter=max_iter, n_init=n_init, init_params=init_params,
random_state=random_state, warm_start=warm_start,
verbose=verbose, verbose_interval=verbose_interval)
self.covariance_type = covariance_type
self.weights_init = weights_init
self.means_init = means_init
self.precisions_init = precisions_init
def _check_parameters(self, X):
"""Check the Gaussian mixture parameters are well defined."""
_, n_features = X.shape
if self.covariance_type not in ['spherical', 'tied', 'diag', 'full']:
raise ValueError("Invalid value for 'covariance_type': %s "
"'covariance_type' should be in "
"['spherical', 'tied', 'diag', 'full']"
% self.covariance_type)
if self.weights_init is not None:
self.weights_init = _check_weights(self.weights_init,
self.n_components)
if self.means_init is not None:
self.means_init = _check_means(self.means_init,
self.n_components, n_features)
if self.precisions_init is not None:
self.precisions_init = _check_precisions(self.precisions_init,
self.covariance_type,
self.n_components,
n_features)
def _initialize(self, X, resp):
"""Initialization of the Gaussian mixture parameters.
Parameters
----------
X : array-like, shape (n_samples, n_features)
resp : array-like, shape (n_samples, n_components)
"""
n_samples, _ = X.shape
weights, means, covariances = _estimate_gaussian_parameters(
X, resp, self.reg_covar, self.covariance_type)
weights /= n_samples
self.weights_ = (weights if self.weights_init is None
else self.weights_init)
self.means_ = means if self.means_init is None else self.means_init
if self.precisions_init is None:
self.covariances_ = covariances
self.precisions_cholesky_ = _compute_precision_cholesky(
covariances, self.covariance_type)
elif self.covariance_type == 'full':
self.precisions_cholesky_ = np.array(
[linalg.cholesky(prec_init, lower=True)
for prec_init in self.precisions_init])
elif self.covariance_type == 'tied':
self.precisions_cholesky_ = linalg.cholesky(self.precisions_init,
lower=True)
else:
self.precisions_cholesky_ = self.precisions_init
def _m_step(self, X, log_resp):
"""M step.
Parameters
----------
X : array-like, shape (n_samples, n_features)
log_resp : array-like, shape (n_samples, n_components)
Logarithm of the posterior probabilities (or responsibilities) of
the point of each sample in X.
"""
n_samples, _ = X.shape
self.weights_, self.means_, self.covariances_ = (
_estimate_gaussian_parameters(X, np.exp(log_resp), self.reg_covar,
self.covariance_type))
self.weights_ /= n_samples
self.precisions_cholesky_ = _compute_precision_cholesky(
self.covariances_, self.covariance_type)
def _estimate_log_prob(self, X):
return _estimate_log_gaussian_prob(
X, self.means_, self.precisions_cholesky_, self.covariance_type)
def _estimate_log_weights(self):
return np.log(self.weights_)
def _compute_lower_bound(self, _, log_prob_norm):
return log_prob_norm
def _get_parameters(self):
return (self.weights_, self.means_, self.covariances_,
self.precisions_cholesky_)
def _set_parameters(self, params):
(self.weights_, self.means_, self.covariances_,
self.precisions_cholesky_) = params
# Attributes computation
_, n_features = self.means_.shape
if self.covariance_type == 'full':
self.precisions_ = np.empty(self.precisions_cholesky_.shape)
for k, prec_chol in enumerate(self.precisions_cholesky_):
self.precisions_[k] = np.dot(prec_chol, prec_chol.T)
elif self.covariance_type == 'tied':
self.precisions_ = np.dot(self.precisions_cholesky_,
self.precisions_cholesky_.T)
else:
self.precisions_ = self.precisions_cholesky_ ** 2
def _n_parameters(self):
"""Return the number of free parameters in the model."""
_, n_features = self.means_.shape
if self.covariance_type == 'full':
cov_params = self.n_components * n_features * (n_features + 1) / 2.
elif self.covariance_type == 'diag':
cov_params = self.n_components * n_features
elif self.covariance_type == 'tied':
cov_params = n_features * (n_features + 1) / 2.
elif self.covariance_type == 'spherical':
cov_params = self.n_components
mean_params = n_features * self.n_components
return int(cov_params + mean_params + self.n_components - 1)
def bic(self, X):
"""Bayesian information criterion for the current model on the input X.
Parameters
----------
X : array of shape (n_samples, n_dimensions)
Returns
-------
bic : float
The lower the better.
"""
return (-2 * self.score(X) * X.shape[0] +
self._n_parameters() * np.log(X.shape[0]))
def aic(self, X):
"""Akaike information criterion for the current model on the input X.
Parameters
----------
X : array of shape (n_samples, n_dimensions)
Returns
-------
aic : float
The lower the better.
"""
return -2 * self.score(X) * X.shape[0] + 2 * self._n_parameters()

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@ -0,0 +1,18 @@
# THIS FILE WAS AUTOMATICALLY GENERATED BY deprecated_modules.py
import sys
# mypy error: Module X has no attribute y (typically for C extensions)
from . import _base # type: ignore
from ..externals._pep562 import Pep562
from ..utils.deprecation import _raise_dep_warning_if_not_pytest
deprecated_path = 'sklearn.mixture.base'
correct_import_path = 'sklearn.mixture'
_raise_dep_warning_if_not_pytest(deprecated_path, correct_import_path)
def __getattr__(name):
return getattr(_base, name)
if not sys.version_info >= (3, 7):
Pep562(__name__)

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@ -0,0 +1,18 @@
# THIS FILE WAS AUTOMATICALLY GENERATED BY deprecated_modules.py
import sys
# mypy error: Module X has no attribute y (typically for C extensions)
from . import _bayesian_mixture # type: ignore
from ..externals._pep562 import Pep562
from ..utils.deprecation import _raise_dep_warning_if_not_pytest
deprecated_path = 'sklearn.mixture.bayesian_mixture'
correct_import_path = 'sklearn.mixture'
_raise_dep_warning_if_not_pytest(deprecated_path, correct_import_path)
def __getattr__(name):
return getattr(_bayesian_mixture, name)
if not sys.version_info >= (3, 7):
Pep562(__name__)

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@ -0,0 +1,18 @@
# THIS FILE WAS AUTOMATICALLY GENERATED BY deprecated_modules.py
import sys
# mypy error: Module X has no attribute y (typically for C extensions)
from . import _gaussian_mixture # type: ignore
from ..externals._pep562 import Pep562
from ..utils.deprecation import _raise_dep_warning_if_not_pytest
deprecated_path = 'sklearn.mixture.gaussian_mixture'
correct_import_path = 'sklearn.mixture'
_raise_dep_warning_if_not_pytest(deprecated_path, correct_import_path)
def __getattr__(name):
return getattr(_gaussian_mixture, name)
if not sys.version_info >= (3, 7):
Pep562(__name__)

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@ -0,0 +1,488 @@
# Author: Wei Xue <xuewei4d@gmail.com>
# Thierry Guillemot <thierry.guillemot.work@gmail.com>
# License: BSD 3 clause
import copy
import numpy as np
from scipy.special import gammaln
import pytest
from sklearn.utils._testing import assert_raise_message
from sklearn.utils._testing import assert_almost_equal
from sklearn.utils._testing import assert_array_equal
from sklearn.metrics.cluster import adjusted_rand_score
from sklearn.mixture._bayesian_mixture import _log_dirichlet_norm
from sklearn.mixture._bayesian_mixture import _log_wishart_norm
from sklearn.mixture import BayesianGaussianMixture
from sklearn.mixture.tests.test_gaussian_mixture import RandomData
from sklearn.exceptions import ConvergenceWarning, NotFittedError
from sklearn.utils._testing import ignore_warnings
COVARIANCE_TYPE = ['full', 'tied', 'diag', 'spherical']
PRIOR_TYPE = ['dirichlet_process', 'dirichlet_distribution']
def test_log_dirichlet_norm():
rng = np.random.RandomState(0)
weight_concentration = rng.rand(2)
expected_norm = (gammaln(np.sum(weight_concentration)) -
np.sum(gammaln(weight_concentration)))
predected_norm = _log_dirichlet_norm(weight_concentration)
assert_almost_equal(expected_norm, predected_norm)
def test_log_wishart_norm():
rng = np.random.RandomState(0)
n_components, n_features = 5, 2
degrees_of_freedom = np.abs(rng.rand(n_components)) + 1.
log_det_precisions_chol = n_features * np.log(range(2, 2 + n_components))
expected_norm = np.empty(5)
for k, (degrees_of_freedom_k, log_det_k) in enumerate(
zip(degrees_of_freedom, log_det_precisions_chol)):
expected_norm[k] = -(
degrees_of_freedom_k * (log_det_k + .5 * n_features * np.log(2.)) +
np.sum(gammaln(.5 * (degrees_of_freedom_k -
np.arange(0, n_features)[:, np.newaxis])), 0))
predected_norm = _log_wishart_norm(degrees_of_freedom,
log_det_precisions_chol, n_features)
assert_almost_equal(expected_norm, predected_norm)
def test_bayesian_mixture_covariance_type():
rng = np.random.RandomState(0)
n_samples, n_features = 10, 2
X = rng.rand(n_samples, n_features)
covariance_type = 'bad_covariance_type'
bgmm = BayesianGaussianMixture(covariance_type=covariance_type,
random_state=rng)
assert_raise_message(ValueError,
"Invalid value for 'covariance_type': %s "
"'covariance_type' should be in "
"['spherical', 'tied', 'diag', 'full']"
% covariance_type, bgmm.fit, X)
def test_bayesian_mixture_weight_concentration_prior_type():
rng = np.random.RandomState(0)
n_samples, n_features = 10, 2
X = rng.rand(n_samples, n_features)
bad_prior_type = 'bad_prior_type'
bgmm = BayesianGaussianMixture(
weight_concentration_prior_type=bad_prior_type, random_state=rng)
assert_raise_message(ValueError,
"Invalid value for 'weight_concentration_prior_type':"
" %s 'weight_concentration_prior_type' should be in "
"['dirichlet_process', 'dirichlet_distribution']"
% bad_prior_type, bgmm.fit, X)
def test_bayesian_mixture_weights_prior_initialisation():
rng = np.random.RandomState(0)
n_samples, n_components, n_features = 10, 5, 2
X = rng.rand(n_samples, n_features)
# Check raise message for a bad value of weight_concentration_prior
bad_weight_concentration_prior_ = 0.
bgmm = BayesianGaussianMixture(
weight_concentration_prior=bad_weight_concentration_prior_,
random_state=0)
assert_raise_message(ValueError,
"The parameter 'weight_concentration_prior' "
"should be greater than 0., but got %.3f."
% bad_weight_concentration_prior_,
bgmm.fit, X)
# Check correct init for a given value of weight_concentration_prior
weight_concentration_prior = rng.rand()
bgmm = BayesianGaussianMixture(
weight_concentration_prior=weight_concentration_prior,
random_state=rng).fit(X)
assert_almost_equal(weight_concentration_prior,
bgmm.weight_concentration_prior_)
# Check correct init for the default value of weight_concentration_prior
bgmm = BayesianGaussianMixture(n_components=n_components,
random_state=rng).fit(X)
assert_almost_equal(1. / n_components, bgmm.weight_concentration_prior_)
def test_bayesian_mixture_mean_prior_initialisation():
rng = np.random.RandomState(0)
n_samples, n_components, n_features = 10, 3, 2
X = rng.rand(n_samples, n_features)
# Check raise message for a bad value of mean_precision_prior
bad_mean_precision_prior_ = 0.
bgmm = BayesianGaussianMixture(
mean_precision_prior=bad_mean_precision_prior_,
random_state=rng)
assert_raise_message(ValueError,
"The parameter 'mean_precision_prior' should be "
"greater than 0., but got %.3f."
% bad_mean_precision_prior_,
bgmm.fit, X)
# Check correct init for a given value of mean_precision_prior
mean_precision_prior = rng.rand()
bgmm = BayesianGaussianMixture(
mean_precision_prior=mean_precision_prior,
random_state=rng).fit(X)
assert_almost_equal(mean_precision_prior, bgmm.mean_precision_prior_)
# Check correct init for the default value of mean_precision_prior
bgmm = BayesianGaussianMixture(random_state=rng).fit(X)
assert_almost_equal(1., bgmm.mean_precision_prior_)
# Check raise message for a bad shape of mean_prior
mean_prior = rng.rand(n_features + 1)
bgmm = BayesianGaussianMixture(n_components=n_components,
mean_prior=mean_prior,
random_state=rng)
assert_raise_message(ValueError,
"The parameter 'means' should have the shape of ",
bgmm.fit, X)
# Check correct init for a given value of mean_prior
mean_prior = rng.rand(n_features)
bgmm = BayesianGaussianMixture(n_components=n_components,
mean_prior=mean_prior,
random_state=rng).fit(X)
assert_almost_equal(mean_prior, bgmm.mean_prior_)
# Check correct init for the default value of bemean_priorta
bgmm = BayesianGaussianMixture(n_components=n_components,
random_state=rng).fit(X)
assert_almost_equal(X.mean(axis=0), bgmm.mean_prior_)
def test_bayesian_mixture_precisions_prior_initialisation():
rng = np.random.RandomState(0)
n_samples, n_features = 10, 2
X = rng.rand(n_samples, n_features)
# Check raise message for a bad value of degrees_of_freedom_prior
bad_degrees_of_freedom_prior_ = n_features - 1.
bgmm = BayesianGaussianMixture(
degrees_of_freedom_prior=bad_degrees_of_freedom_prior_,
random_state=rng)
assert_raise_message(ValueError,
"The parameter 'degrees_of_freedom_prior' should be "
"greater than %d, but got %.3f."
% (n_features - 1, bad_degrees_of_freedom_prior_),
bgmm.fit, X)
# Check correct init for a given value of degrees_of_freedom_prior
degrees_of_freedom_prior = rng.rand() + n_features - 1.
bgmm = BayesianGaussianMixture(
degrees_of_freedom_prior=degrees_of_freedom_prior,
random_state=rng).fit(X)
assert_almost_equal(degrees_of_freedom_prior,
bgmm.degrees_of_freedom_prior_)
# Check correct init for the default value of degrees_of_freedom_prior
degrees_of_freedom_prior_default = n_features
bgmm = BayesianGaussianMixture(
degrees_of_freedom_prior=degrees_of_freedom_prior_default,
random_state=rng).fit(X)
assert_almost_equal(degrees_of_freedom_prior_default,
bgmm.degrees_of_freedom_prior_)
# Check correct init for a given value of covariance_prior
covariance_prior = {
'full': np.cov(X.T, bias=1) + 10,
'tied': np.cov(X.T, bias=1) + 5,
'diag': np.diag(np.atleast_2d(np.cov(X.T, bias=1))) + 3,
'spherical': rng.rand()}
bgmm = BayesianGaussianMixture(random_state=rng)
for cov_type in ['full', 'tied', 'diag', 'spherical']:
bgmm.covariance_type = cov_type
bgmm.covariance_prior = covariance_prior[cov_type]
bgmm.fit(X)
assert_almost_equal(covariance_prior[cov_type],
bgmm.covariance_prior_)
# Check raise message for a bad spherical value of covariance_prior
bad_covariance_prior_ = -1.
bgmm = BayesianGaussianMixture(covariance_type='spherical',
covariance_prior=bad_covariance_prior_,
random_state=rng)
assert_raise_message(ValueError,
"The parameter 'spherical covariance_prior' "
"should be greater than 0., but got %.3f."
% bad_covariance_prior_,
bgmm.fit, X)
# Check correct init for the default value of covariance_prior
covariance_prior_default = {
'full': np.atleast_2d(np.cov(X.T)),
'tied': np.atleast_2d(np.cov(X.T)),
'diag': np.var(X, axis=0, ddof=1),
'spherical': np.var(X, axis=0, ddof=1).mean()}
bgmm = BayesianGaussianMixture(random_state=0)
for cov_type in ['full', 'tied', 'diag', 'spherical']:
bgmm.covariance_type = cov_type
bgmm.fit(X)
assert_almost_equal(covariance_prior_default[cov_type],
bgmm.covariance_prior_)
def test_bayesian_mixture_check_is_fitted():
rng = np.random.RandomState(0)
n_samples, n_features = 10, 2
# Check raise message
bgmm = BayesianGaussianMixture(random_state=rng)
X = rng.rand(n_samples, n_features)
assert_raise_message(ValueError,
'This BayesianGaussianMixture instance is not '
'fitted yet.', bgmm.score, X)
def test_bayesian_mixture_weights():
rng = np.random.RandomState(0)
n_samples, n_features = 10, 2
X = rng.rand(n_samples, n_features)
# Case Dirichlet distribution for the weight concentration prior type
bgmm = BayesianGaussianMixture(
weight_concentration_prior_type="dirichlet_distribution",
n_components=3, random_state=rng).fit(X)
expected_weights = (bgmm.weight_concentration_ /
np.sum(bgmm.weight_concentration_))
assert_almost_equal(expected_weights, bgmm.weights_)
assert_almost_equal(np.sum(bgmm.weights_), 1.0)
# Case Dirichlet process for the weight concentration prior type
dpgmm = BayesianGaussianMixture(
weight_concentration_prior_type="dirichlet_process",
n_components=3, random_state=rng).fit(X)
weight_dirichlet_sum = (dpgmm.weight_concentration_[0] +
dpgmm.weight_concentration_[1])
tmp = dpgmm.weight_concentration_[1] / weight_dirichlet_sum
expected_weights = (dpgmm.weight_concentration_[0] / weight_dirichlet_sum *
np.hstack((1, np.cumprod(tmp[:-1]))))
expected_weights /= np.sum(expected_weights)
assert_almost_equal(expected_weights, dpgmm.weights_)
assert_almost_equal(np.sum(dpgmm.weights_), 1.0)
@ignore_warnings(category=ConvergenceWarning)
def test_monotonic_likelihood():
# We check that each step of the each step of variational inference without
# regularization improve monotonically the training set of the bound
rng = np.random.RandomState(0)
rand_data = RandomData(rng, scale=20)
n_components = rand_data.n_components
for prior_type in PRIOR_TYPE:
for covar_type in COVARIANCE_TYPE:
X = rand_data.X[covar_type]
bgmm = BayesianGaussianMixture(
weight_concentration_prior_type=prior_type,
n_components=2 * n_components, covariance_type=covar_type,
warm_start=True, max_iter=1, random_state=rng, tol=1e-3)
current_lower_bound = -np.infty
# Do one training iteration at a time so we can make sure that the
# training log likelihood increases after each iteration.
for _ in range(600):
prev_lower_bound = current_lower_bound
current_lower_bound = bgmm.fit(X).lower_bound_
assert current_lower_bound >= prev_lower_bound
if bgmm.converged_:
break
assert(bgmm.converged_)
def test_compare_covar_type():
# We can compare the 'full' precision with the other cov_type if we apply
# 1 iter of the M-step (done during _initialize_parameters).
rng = np.random.RandomState(0)
rand_data = RandomData(rng, scale=7)
X = rand_data.X['full']
n_components = rand_data.n_components
for prior_type in PRIOR_TYPE:
# Computation of the full_covariance
bgmm = BayesianGaussianMixture(
weight_concentration_prior_type=prior_type,
n_components=2 * n_components, covariance_type='full',
max_iter=1, random_state=0, tol=1e-7)
bgmm._check_initial_parameters(X)
bgmm._initialize_parameters(X, np.random.RandomState(0))
full_covariances = (
bgmm.covariances_ *
bgmm.degrees_of_freedom_[:, np.newaxis, np.newaxis])
# Check tied_covariance = mean(full_covariances, 0)
bgmm = BayesianGaussianMixture(
weight_concentration_prior_type=prior_type,
n_components=2 * n_components, covariance_type='tied',
max_iter=1, random_state=0, tol=1e-7)
bgmm._check_initial_parameters(X)
bgmm._initialize_parameters(X, np.random.RandomState(0))
tied_covariance = bgmm.covariances_ * bgmm.degrees_of_freedom_
assert_almost_equal(tied_covariance, np.mean(full_covariances, 0))
# Check diag_covariance = diag(full_covariances)
bgmm = BayesianGaussianMixture(
weight_concentration_prior_type=prior_type,
n_components=2 * n_components, covariance_type='diag',
max_iter=1, random_state=0, tol=1e-7)
bgmm._check_initial_parameters(X)
bgmm._initialize_parameters(X, np.random.RandomState(0))
diag_covariances = (bgmm.covariances_ *
bgmm.degrees_of_freedom_[:, np.newaxis])
assert_almost_equal(diag_covariances,
np.array([np.diag(cov)
for cov in full_covariances]))
# Check spherical_covariance = np.mean(diag_covariances, 0)
bgmm = BayesianGaussianMixture(
weight_concentration_prior_type=prior_type,
n_components=2 * n_components, covariance_type='spherical',
max_iter=1, random_state=0, tol=1e-7)
bgmm._check_initial_parameters(X)
bgmm._initialize_parameters(X, np.random.RandomState(0))
spherical_covariances = bgmm.covariances_ * bgmm.degrees_of_freedom_
assert_almost_equal(
spherical_covariances, np.mean(diag_covariances, 1))
@ignore_warnings(category=ConvergenceWarning)
def test_check_covariance_precision():
# We check that the dot product of the covariance and the precision
# matrices is identity.
rng = np.random.RandomState(0)
rand_data = RandomData(rng, scale=7)
n_components, n_features = 2 * rand_data.n_components, 2
# Computation of the full_covariance
bgmm = BayesianGaussianMixture(n_components=n_components,
max_iter=100, random_state=rng, tol=1e-3,
reg_covar=0)
for covar_type in COVARIANCE_TYPE:
bgmm.covariance_type = covar_type
bgmm.fit(rand_data.X[covar_type])
if covar_type == 'full':
for covar, precision in zip(bgmm.covariances_, bgmm.precisions_):
assert_almost_equal(np.dot(covar, precision),
np.eye(n_features))
elif covar_type == 'tied':
assert_almost_equal(np.dot(bgmm.covariances_, bgmm.precisions_),
np.eye(n_features))
elif covar_type == 'diag':
assert_almost_equal(bgmm.covariances_ * bgmm.precisions_,
np.ones((n_components, n_features)))
else:
assert_almost_equal(bgmm.covariances_ * bgmm.precisions_,
np.ones(n_components))
@ignore_warnings(category=ConvergenceWarning)
def test_invariant_translation():
# We check here that adding a constant in the data change correctly the
# parameters of the mixture
rng = np.random.RandomState(0)
rand_data = RandomData(rng, scale=100)
n_components = 2 * rand_data.n_components
for prior_type in PRIOR_TYPE:
for covar_type in COVARIANCE_TYPE:
X = rand_data.X[covar_type]
bgmm1 = BayesianGaussianMixture(
weight_concentration_prior_type=prior_type,
n_components=n_components, max_iter=100, random_state=0,
tol=1e-3, reg_covar=0).fit(X)
bgmm2 = BayesianGaussianMixture(
weight_concentration_prior_type=prior_type,
n_components=n_components, max_iter=100, random_state=0,
tol=1e-3, reg_covar=0).fit(X + 100)
assert_almost_equal(bgmm1.means_, bgmm2.means_ - 100)
assert_almost_equal(bgmm1.weights_, bgmm2.weights_)
assert_almost_equal(bgmm1.covariances_, bgmm2.covariances_)
@pytest.mark.filterwarnings("ignore:.*did not converge.*")
@pytest.mark.parametrize('seed, max_iter, tol', [
(0, 2, 1e-7), # strict non-convergence
(1, 2, 1e-1), # loose non-convergence
(3, 300, 1e-7), # strict convergence
(4, 300, 1e-1), # loose convergence
])
def test_bayesian_mixture_fit_predict(seed, max_iter, tol):
rng = np.random.RandomState(seed)
rand_data = RandomData(rng, n_samples=50, scale=7)
n_components = 2 * rand_data.n_components
for covar_type in COVARIANCE_TYPE:
bgmm1 = BayesianGaussianMixture(n_components=n_components,
max_iter=max_iter, random_state=rng,
tol=tol, reg_covar=0)
bgmm1.covariance_type = covar_type
bgmm2 = copy.deepcopy(bgmm1)
X = rand_data.X[covar_type]
Y_pred1 = bgmm1.fit(X).predict(X)
Y_pred2 = bgmm2.fit_predict(X)
assert_array_equal(Y_pred1, Y_pred2)
def test_bayesian_mixture_fit_predict_n_init():
# Check that fit_predict is equivalent to fit.predict, when n_init > 1
X = np.random.RandomState(0).randn(50, 5)
gm = BayesianGaussianMixture(n_components=5, n_init=10, random_state=0)
y_pred1 = gm.fit_predict(X)
y_pred2 = gm.predict(X)
assert_array_equal(y_pred1, y_pred2)
def test_bayesian_mixture_predict_predict_proba():
# this is the same test as test_gaussian_mixture_predict_predict_proba()
rng = np.random.RandomState(0)
rand_data = RandomData(rng)
for prior_type in PRIOR_TYPE:
for covar_type in COVARIANCE_TYPE:
X = rand_data.X[covar_type]
Y = rand_data.Y
bgmm = BayesianGaussianMixture(
n_components=rand_data.n_components,
random_state=rng,
weight_concentration_prior_type=prior_type,
covariance_type=covar_type)
# Check a warning message arrive if we don't do fit
assert_raise_message(NotFittedError,
"This BayesianGaussianMixture instance"
" is not fitted yet. Call 'fit' with "
"appropriate arguments before using "
"this estimator.", bgmm.predict, X)
bgmm.fit(X)
Y_pred = bgmm.predict(X)
Y_pred_proba = bgmm.predict_proba(X).argmax(axis=1)
assert_array_equal(Y_pred, Y_pred_proba)
assert adjusted_rand_score(Y, Y_pred) >= .95

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# Author: Guillaume Lemaitre <g.lemaitre58@gmail.com>
# License: BSD 3 clause
import pytest
import numpy as np
from sklearn.mixture import GaussianMixture
from sklearn.mixture import BayesianGaussianMixture
@pytest.mark.parametrize(
"estimator",
[GaussianMixture(),
BayesianGaussianMixture()]
)
def test_gaussian_mixture_n_iter(estimator):
# check that n_iter is the number of iteration performed.
rng = np.random.RandomState(0)
X = rng.rand(10, 5)
max_iter = 1
estimator.set_params(max_iter=max_iter)
estimator.fit(X)
assert estimator.n_iter_ == max_iter