925 lines
32 KiB
Python
925 lines
32 KiB
Python
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"""
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=============================================================
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Online Latent Dirichlet Allocation with variational inference
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=============================================================
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This implementation is modified from Matthew D. Hoffman's onlineldavb code
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Link: https://github.com/blei-lab/onlineldavb
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"""
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# Author: Chyi-Kwei Yau
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# Author: Matthew D. Hoffman (original onlineldavb implementation)
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from numbers import Integral, Real
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import numpy as np
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import scipy.sparse as sp
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from scipy.special import gammaln, logsumexp
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from joblib import effective_n_jobs
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from ..base import BaseEstimator, TransformerMixin, ClassNamePrefixFeaturesOutMixin
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from ..utils import check_random_state, gen_batches, gen_even_slices
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from ..utils.validation import check_non_negative
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from ..utils.validation import check_is_fitted
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from ..utils.parallel import delayed, Parallel
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from ..utils._param_validation import Interval, StrOptions
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from ._online_lda_fast import (
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mean_change as cy_mean_change,
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_dirichlet_expectation_1d as cy_dirichlet_expectation_1d,
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_dirichlet_expectation_2d,
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)
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EPS = np.finfo(float).eps
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def _update_doc_distribution(
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X,
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exp_topic_word_distr,
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doc_topic_prior,
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max_doc_update_iter,
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mean_change_tol,
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cal_sstats,
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random_state,
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):
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"""E-step: update document-topic distribution.
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Parameters
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----------
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X : {array-like, sparse matrix} of shape (n_samples, n_features)
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Document word matrix.
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exp_topic_word_distr : ndarray of shape (n_topics, n_features)
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Exponential value of expectation of log topic word distribution.
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In the literature, this is `exp(E[log(beta)])`.
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doc_topic_prior : float
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Prior of document topic distribution `theta`.
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max_doc_update_iter : int
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Max number of iterations for updating document topic distribution in
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the E-step.
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mean_change_tol : float
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Stopping tolerance for updating document topic distribution in E-step.
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cal_sstats : bool
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Parameter that indicate to calculate sufficient statistics or not.
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Set `cal_sstats` to `True` when we need to run M-step.
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random_state : RandomState instance or None
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Parameter that indicate how to initialize document topic distribution.
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Set `random_state` to None will initialize document topic distribution
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to a constant number.
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Returns
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-------
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(doc_topic_distr, suff_stats) :
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`doc_topic_distr` is unnormalized topic distribution for each document.
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In the literature, this is `gamma`. we can calculate `E[log(theta)]`
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from it.
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`suff_stats` is expected sufficient statistics for the M-step.
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When `cal_sstats == False`, this will be None.
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"""
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is_sparse_x = sp.issparse(X)
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n_samples, n_features = X.shape
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n_topics = exp_topic_word_distr.shape[0]
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if random_state:
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doc_topic_distr = random_state.gamma(100.0, 0.01, (n_samples, n_topics)).astype(
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X.dtype, copy=False
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)
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else:
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doc_topic_distr = np.ones((n_samples, n_topics), dtype=X.dtype)
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# In the literature, this is `exp(E[log(theta)])`
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exp_doc_topic = np.exp(_dirichlet_expectation_2d(doc_topic_distr))
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# diff on `component_` (only calculate it when `cal_diff` is True)
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suff_stats = (
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np.zeros(exp_topic_word_distr.shape, dtype=X.dtype) if cal_sstats else None
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)
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if is_sparse_x:
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X_data = X.data
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X_indices = X.indices
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X_indptr = X.indptr
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# These cython functions are called in a nested loop on usually very small arrays
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# (lenght=n_topics). In that case, finding the appropriate signature of the
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# fused-typed function can be more costly than its execution, hence the dispatch
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# is done outside of the loop.
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ctype = "float" if X.dtype == np.float32 else "double"
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mean_change = cy_mean_change[ctype]
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dirichlet_expectation_1d = cy_dirichlet_expectation_1d[ctype]
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eps = np.finfo(X.dtype).eps
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for idx_d in range(n_samples):
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if is_sparse_x:
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ids = X_indices[X_indptr[idx_d] : X_indptr[idx_d + 1]]
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cnts = X_data[X_indptr[idx_d] : X_indptr[idx_d + 1]]
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else:
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ids = np.nonzero(X[idx_d, :])[0]
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cnts = X[idx_d, ids]
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doc_topic_d = doc_topic_distr[idx_d, :]
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# The next one is a copy, since the inner loop overwrites it.
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exp_doc_topic_d = exp_doc_topic[idx_d, :].copy()
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exp_topic_word_d = exp_topic_word_distr[:, ids]
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# Iterate between `doc_topic_d` and `norm_phi` until convergence
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for _ in range(0, max_doc_update_iter):
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last_d = doc_topic_d
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# The optimal phi_{dwk} is proportional to
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# exp(E[log(theta_{dk})]) * exp(E[log(beta_{dw})]).
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norm_phi = np.dot(exp_doc_topic_d, exp_topic_word_d) + eps
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doc_topic_d = exp_doc_topic_d * np.dot(cnts / norm_phi, exp_topic_word_d.T)
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# Note: adds doc_topic_prior to doc_topic_d, in-place.
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dirichlet_expectation_1d(doc_topic_d, doc_topic_prior, exp_doc_topic_d)
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if mean_change(last_d, doc_topic_d) < mean_change_tol:
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break
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doc_topic_distr[idx_d, :] = doc_topic_d
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# Contribution of document d to the expected sufficient
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# statistics for the M step.
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if cal_sstats:
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norm_phi = np.dot(exp_doc_topic_d, exp_topic_word_d) + eps
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suff_stats[:, ids] += np.outer(exp_doc_topic_d, cnts / norm_phi)
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return (doc_topic_distr, suff_stats)
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class LatentDirichletAllocation(
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ClassNamePrefixFeaturesOutMixin, TransformerMixin, BaseEstimator
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):
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"""Latent Dirichlet Allocation with online variational Bayes algorithm.
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The implementation is based on [1]_ and [2]_.
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.. versionadded:: 0.17
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Read more in the :ref:`User Guide <LatentDirichletAllocation>`.
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Parameters
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----------
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n_components : int, default=10
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Number of topics.
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.. versionchanged:: 0.19
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``n_topics`` was renamed to ``n_components``
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doc_topic_prior : float, default=None
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Prior of document topic distribution `theta`. If the value is None,
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defaults to `1 / n_components`.
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In [1]_, this is called `alpha`.
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topic_word_prior : float, default=None
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Prior of topic word distribution `beta`. If the value is None, defaults
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to `1 / n_components`.
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In [1]_, this is called `eta`.
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learning_method : {'batch', 'online'}, default='batch'
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Method used to update `_component`. Only used in :meth:`fit` method.
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In general, if the data size is large, the online update will be much
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faster than the batch update.
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Valid options::
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'batch': Batch variational Bayes method. Use all training data in
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each EM update.
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Old `components_` will be overwritten in each iteration.
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'online': Online variational Bayes method. In each EM update, use
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mini-batch of training data to update the ``components_``
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variable incrementally. The learning rate is controlled by the
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``learning_decay`` and the ``learning_offset`` parameters.
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.. versionchanged:: 0.20
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The default learning method is now ``"batch"``.
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learning_decay : float, default=0.7
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It is a parameter that control learning rate in the online learning
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method. The value should be set between (0.5, 1.0] to guarantee
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asymptotic convergence. When the value is 0.0 and batch_size is
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``n_samples``, the update method is same as batch learning. In the
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literature, this is called kappa.
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learning_offset : float, default=10.0
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A (positive) parameter that downweights early iterations in online
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learning. It should be greater than 1.0. In the literature, this is
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called tau_0.
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max_iter : int, default=10
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The maximum number of passes over the training data (aka epochs).
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It only impacts the behavior in the :meth:`fit` method, and not the
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:meth:`partial_fit` method.
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batch_size : int, default=128
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Number of documents to use in each EM iteration. Only used in online
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learning.
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evaluate_every : int, default=-1
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How often to evaluate perplexity. Only used in `fit` method.
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set it to 0 or negative number to not evaluate perplexity in
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training at all. Evaluating perplexity can help you check convergence
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in training process, but it will also increase total training time.
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Evaluating perplexity in every iteration might increase training time
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up to two-fold.
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total_samples : int, default=1e6
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Total number of documents. Only used in the :meth:`partial_fit` method.
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perp_tol : float, default=1e-1
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Perplexity tolerance in batch learning. Only used when
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``evaluate_every`` is greater than 0.
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mean_change_tol : float, default=1e-3
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Stopping tolerance for updating document topic distribution in E-step.
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max_doc_update_iter : int, default=100
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Max number of iterations for updating document topic distribution in
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the E-step.
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n_jobs : int, default=None
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The number of jobs to use in the E-step.
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``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
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``-1`` means using all processors. See :term:`Glossary <n_jobs>`
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for more details.
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verbose : int, default=0
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Verbosity level.
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random_state : int, RandomState instance or None, default=None
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Pass an int for reproducible results across multiple function calls.
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See :term:`Glossary <random_state>`.
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Attributes
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----------
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components_ : ndarray of shape (n_components, n_features)
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Variational parameters for topic word distribution. Since the complete
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conditional for topic word distribution is a Dirichlet,
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``components_[i, j]`` can be viewed as pseudocount that represents the
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number of times word `j` was assigned to topic `i`.
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It can also be viewed as distribution over the words for each topic
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after normalization:
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``model.components_ / model.components_.sum(axis=1)[:, np.newaxis]``.
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exp_dirichlet_component_ : ndarray of shape (n_components, n_features)
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Exponential value of expectation of log topic word distribution.
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In the literature, this is `exp(E[log(beta)])`.
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n_batch_iter_ : int
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Number of iterations of the EM step.
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n_features_in_ : int
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Number of features seen during :term:`fit`.
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.. versionadded:: 0.24
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feature_names_in_ : ndarray of shape (`n_features_in_`,)
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Names of features seen during :term:`fit`. Defined only when `X`
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has feature names that are all strings.
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.. versionadded:: 1.0
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n_iter_ : int
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Number of passes over the dataset.
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bound_ : float
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Final perplexity score on training set.
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doc_topic_prior_ : float
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Prior of document topic distribution `theta`. If the value is None,
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it is `1 / n_components`.
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random_state_ : RandomState instance
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RandomState instance that is generated either from a seed, the random
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number generator or by `np.random`.
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topic_word_prior_ : float
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Prior of topic word distribution `beta`. If the value is None, it is
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`1 / n_components`.
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See Also
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--------
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sklearn.discriminant_analysis.LinearDiscriminantAnalysis:
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A classifier with a linear decision boundary, generated by fitting
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class conditional densities to the data and using Bayes' rule.
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References
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----------
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.. [1] "Online Learning for Latent Dirichlet Allocation", Matthew D.
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Hoffman, David M. Blei, Francis Bach, 2010
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https://github.com/blei-lab/onlineldavb
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.. [2] "Stochastic Variational Inference", Matthew D. Hoffman,
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David M. Blei, Chong Wang, John Paisley, 2013
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Examples
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--------
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>>> from sklearn.decomposition import LatentDirichletAllocation
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>>> from sklearn.datasets import make_multilabel_classification
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>>> # This produces a feature matrix of token counts, similar to what
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>>> # CountVectorizer would produce on text.
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>>> X, _ = make_multilabel_classification(random_state=0)
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>>> lda = LatentDirichletAllocation(n_components=5,
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... random_state=0)
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>>> lda.fit(X)
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LatentDirichletAllocation(...)
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>>> # get topics for some given samples:
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>>> lda.transform(X[-2:])
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array([[0.00360392, 0.25499205, 0.0036211 , 0.64236448, 0.09541846],
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[0.15297572, 0.00362644, 0.44412786, 0.39568399, 0.003586 ]])
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"""
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_parameter_constraints: dict = {
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"n_components": [Interval(Integral, 0, None, closed="neither")],
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"doc_topic_prior": [None, Interval(Real, 0, 1, closed="both")],
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"topic_word_prior": [None, Interval(Real, 0, 1, closed="both")],
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"learning_method": [StrOptions({"batch", "online"})],
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"learning_decay": [Interval(Real, 0, 1, closed="both")],
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"learning_offset": [Interval(Real, 1.0, None, closed="left")],
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"max_iter": [Interval(Integral, 0, None, closed="left")],
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"batch_size": [Interval(Integral, 0, None, closed="neither")],
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"evaluate_every": [Interval(Integral, None, None, closed="neither")],
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"total_samples": [Interval(Real, 0, None, closed="neither")],
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"perp_tol": [Interval(Real, 0, None, closed="left")],
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"mean_change_tol": [Interval(Real, 0, None, closed="left")],
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"max_doc_update_iter": [Interval(Integral, 0, None, closed="left")],
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"n_jobs": [None, Integral],
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||
|
|
"verbose": ["verbose"],
|
||
|
|
"random_state": ["random_state"],
|
||
|
|
}
|
||
|
|
|
||
|
|
def __init__(
|
||
|
|
self,
|
||
|
|
n_components=10,
|
||
|
|
*,
|
||
|
|
doc_topic_prior=None,
|
||
|
|
topic_word_prior=None,
|
||
|
|
learning_method="batch",
|
||
|
|
learning_decay=0.7,
|
||
|
|
learning_offset=10.0,
|
||
|
|
max_iter=10,
|
||
|
|
batch_size=128,
|
||
|
|
evaluate_every=-1,
|
||
|
|
total_samples=1e6,
|
||
|
|
perp_tol=1e-1,
|
||
|
|
mean_change_tol=1e-3,
|
||
|
|
max_doc_update_iter=100,
|
||
|
|
n_jobs=None,
|
||
|
|
verbose=0,
|
||
|
|
random_state=None,
|
||
|
|
):
|
||
|
|
self.n_components = n_components
|
||
|
|
self.doc_topic_prior = doc_topic_prior
|
||
|
|
self.topic_word_prior = topic_word_prior
|
||
|
|
self.learning_method = learning_method
|
||
|
|
self.learning_decay = learning_decay
|
||
|
|
self.learning_offset = learning_offset
|
||
|
|
self.max_iter = max_iter
|
||
|
|
self.batch_size = batch_size
|
||
|
|
self.evaluate_every = evaluate_every
|
||
|
|
self.total_samples = total_samples
|
||
|
|
self.perp_tol = perp_tol
|
||
|
|
self.mean_change_tol = mean_change_tol
|
||
|
|
self.max_doc_update_iter = max_doc_update_iter
|
||
|
|
self.n_jobs = n_jobs
|
||
|
|
self.verbose = verbose
|
||
|
|
self.random_state = random_state
|
||
|
|
|
||
|
|
def _init_latent_vars(self, n_features, dtype=np.float64):
|
||
|
|
"""Initialize latent variables."""
|
||
|
|
|
||
|
|
self.random_state_ = check_random_state(self.random_state)
|
||
|
|
self.n_batch_iter_ = 1
|
||
|
|
self.n_iter_ = 0
|
||
|
|
|
||
|
|
if self.doc_topic_prior is None:
|
||
|
|
self.doc_topic_prior_ = 1.0 / self.n_components
|
||
|
|
else:
|
||
|
|
self.doc_topic_prior_ = self.doc_topic_prior
|
||
|
|
|
||
|
|
if self.topic_word_prior is None:
|
||
|
|
self.topic_word_prior_ = 1.0 / self.n_components
|
||
|
|
else:
|
||
|
|
self.topic_word_prior_ = self.topic_word_prior
|
||
|
|
|
||
|
|
init_gamma = 100.0
|
||
|
|
init_var = 1.0 / init_gamma
|
||
|
|
# In the literature, this is called `lambda`
|
||
|
|
self.components_ = self.random_state_.gamma(
|
||
|
|
init_gamma, init_var, (self.n_components, n_features)
|
||
|
|
).astype(dtype, copy=False)
|
||
|
|
|
||
|
|
# In the literature, this is `exp(E[log(beta)])`
|
||
|
|
self.exp_dirichlet_component_ = np.exp(
|
||
|
|
_dirichlet_expectation_2d(self.components_)
|
||
|
|
)
|
||
|
|
|
||
|
|
def _e_step(self, X, cal_sstats, random_init, parallel=None):
|
||
|
|
"""E-step in EM update.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
cal_sstats : bool
|
||
|
|
Parameter that indicate whether to calculate sufficient statistics
|
||
|
|
or not. Set ``cal_sstats`` to True when we need to run M-step.
|
||
|
|
|
||
|
|
random_init : bool
|
||
|
|
Parameter that indicate whether to initialize document topic
|
||
|
|
distribution randomly in the E-step. Set it to True in training
|
||
|
|
steps.
|
||
|
|
|
||
|
|
parallel : joblib.Parallel, default=None
|
||
|
|
Pre-initialized instance of joblib.Parallel.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
(doc_topic_distr, suff_stats) :
|
||
|
|
`doc_topic_distr` is unnormalized topic distribution for each
|
||
|
|
document. In the literature, this is called `gamma`.
|
||
|
|
`suff_stats` is expected sufficient statistics for the M-step.
|
||
|
|
When `cal_sstats == False`, it will be None.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
# Run e-step in parallel
|
||
|
|
random_state = self.random_state_ if random_init else None
|
||
|
|
|
||
|
|
# TODO: make Parallel._effective_n_jobs public instead?
|
||
|
|
n_jobs = effective_n_jobs(self.n_jobs)
|
||
|
|
if parallel is None:
|
||
|
|
parallel = Parallel(n_jobs=n_jobs, verbose=max(0, self.verbose - 1))
|
||
|
|
results = parallel(
|
||
|
|
delayed(_update_doc_distribution)(
|
||
|
|
X[idx_slice, :],
|
||
|
|
self.exp_dirichlet_component_,
|
||
|
|
self.doc_topic_prior_,
|
||
|
|
self.max_doc_update_iter,
|
||
|
|
self.mean_change_tol,
|
||
|
|
cal_sstats,
|
||
|
|
random_state,
|
||
|
|
)
|
||
|
|
for idx_slice in gen_even_slices(X.shape[0], n_jobs)
|
||
|
|
)
|
||
|
|
|
||
|
|
# merge result
|
||
|
|
doc_topics, sstats_list = zip(*results)
|
||
|
|
doc_topic_distr = np.vstack(doc_topics)
|
||
|
|
|
||
|
|
if cal_sstats:
|
||
|
|
# This step finishes computing the sufficient statistics for the
|
||
|
|
# M-step.
|
||
|
|
suff_stats = np.zeros(self.components_.shape, dtype=self.components_.dtype)
|
||
|
|
for sstats in sstats_list:
|
||
|
|
suff_stats += sstats
|
||
|
|
suff_stats *= self.exp_dirichlet_component_
|
||
|
|
else:
|
||
|
|
suff_stats = None
|
||
|
|
|
||
|
|
return (doc_topic_distr, suff_stats)
|
||
|
|
|
||
|
|
def _em_step(self, X, total_samples, batch_update, parallel=None):
|
||
|
|
"""EM update for 1 iteration.
|
||
|
|
|
||
|
|
update `_component` by batch VB or online VB.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
total_samples : int
|
||
|
|
Total number of documents. It is only used when
|
||
|
|
batch_update is `False`.
|
||
|
|
|
||
|
|
batch_update : bool
|
||
|
|
Parameter that controls updating method.
|
||
|
|
`True` for batch learning, `False` for online learning.
|
||
|
|
|
||
|
|
parallel : joblib.Parallel, default=None
|
||
|
|
Pre-initialized instance of joblib.Parallel
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
doc_topic_distr : ndarray of shape (n_samples, n_components)
|
||
|
|
Unnormalized document topic distribution.
|
||
|
|
"""
|
||
|
|
|
||
|
|
# E-step
|
||
|
|
_, suff_stats = self._e_step(
|
||
|
|
X, cal_sstats=True, random_init=True, parallel=parallel
|
||
|
|
)
|
||
|
|
|
||
|
|
# M-step
|
||
|
|
if batch_update:
|
||
|
|
self.components_ = self.topic_word_prior_ + suff_stats
|
||
|
|
else:
|
||
|
|
# online update
|
||
|
|
# In the literature, the weight is `rho`
|
||
|
|
weight = np.power(
|
||
|
|
self.learning_offset + self.n_batch_iter_, -self.learning_decay
|
||
|
|
)
|
||
|
|
doc_ratio = float(total_samples) / X.shape[0]
|
||
|
|
self.components_ *= 1 - weight
|
||
|
|
self.components_ += weight * (
|
||
|
|
self.topic_word_prior_ + doc_ratio * suff_stats
|
||
|
|
)
|
||
|
|
|
||
|
|
# update `component_` related variables
|
||
|
|
self.exp_dirichlet_component_ = np.exp(
|
||
|
|
_dirichlet_expectation_2d(self.components_)
|
||
|
|
)
|
||
|
|
self.n_batch_iter_ += 1
|
||
|
|
return
|
||
|
|
|
||
|
|
def _more_tags(self):
|
||
|
|
return {
|
||
|
|
"preserves_dtype": [np.float64, np.float32],
|
||
|
|
"requires_positive_X": True,
|
||
|
|
}
|
||
|
|
|
||
|
|
def _check_non_neg_array(self, X, reset_n_features, whom):
|
||
|
|
"""check X format
|
||
|
|
|
||
|
|
check X format and make sure no negative value in X.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : array-like or sparse matrix
|
||
|
|
|
||
|
|
"""
|
||
|
|
dtype = [np.float64, np.float32] if reset_n_features else self.components_.dtype
|
||
|
|
|
||
|
|
X = self._validate_data(
|
||
|
|
X,
|
||
|
|
reset=reset_n_features,
|
||
|
|
accept_sparse="csr",
|
||
|
|
dtype=dtype,
|
||
|
|
)
|
||
|
|
check_non_negative(X, whom)
|
||
|
|
|
||
|
|
return X
|
||
|
|
|
||
|
|
def partial_fit(self, X, y=None):
|
||
|
|
"""Online VB with Mini-Batch update.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
y : Ignored
|
||
|
|
Not used, present here for API consistency by convention.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
self
|
||
|
|
Partially fitted estimator.
|
||
|
|
"""
|
||
|
|
first_time = not hasattr(self, "components_")
|
||
|
|
|
||
|
|
if first_time:
|
||
|
|
self._validate_params()
|
||
|
|
|
||
|
|
X = self._check_non_neg_array(
|
||
|
|
X, reset_n_features=first_time, whom="LatentDirichletAllocation.partial_fit"
|
||
|
|
)
|
||
|
|
n_samples, n_features = X.shape
|
||
|
|
batch_size = self.batch_size
|
||
|
|
|
||
|
|
# initialize parameters or check
|
||
|
|
if first_time:
|
||
|
|
self._init_latent_vars(n_features, dtype=X.dtype)
|
||
|
|
|
||
|
|
if n_features != self.components_.shape[1]:
|
||
|
|
raise ValueError(
|
||
|
|
"The provided data has %d dimensions while "
|
||
|
|
"the model was trained with feature size %d."
|
||
|
|
% (n_features, self.components_.shape[1])
|
||
|
|
)
|
||
|
|
|
||
|
|
n_jobs = effective_n_jobs(self.n_jobs)
|
||
|
|
with Parallel(n_jobs=n_jobs, verbose=max(0, self.verbose - 1)) as parallel:
|
||
|
|
for idx_slice in gen_batches(n_samples, batch_size):
|
||
|
|
self._em_step(
|
||
|
|
X[idx_slice, :],
|
||
|
|
total_samples=self.total_samples,
|
||
|
|
batch_update=False,
|
||
|
|
parallel=parallel,
|
||
|
|
)
|
||
|
|
|
||
|
|
return self
|
||
|
|
|
||
|
|
def fit(self, X, y=None):
|
||
|
|
"""Learn model for the data X with variational Bayes method.
|
||
|
|
|
||
|
|
When `learning_method` is 'online', use mini-batch update.
|
||
|
|
Otherwise, use batch update.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
y : Ignored
|
||
|
|
Not used, present here for API consistency by convention.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
self
|
||
|
|
Fitted estimator.
|
||
|
|
"""
|
||
|
|
self._validate_params()
|
||
|
|
X = self._check_non_neg_array(
|
||
|
|
X, reset_n_features=True, whom="LatentDirichletAllocation.fit"
|
||
|
|
)
|
||
|
|
n_samples, n_features = X.shape
|
||
|
|
max_iter = self.max_iter
|
||
|
|
evaluate_every = self.evaluate_every
|
||
|
|
learning_method = self.learning_method
|
||
|
|
|
||
|
|
batch_size = self.batch_size
|
||
|
|
|
||
|
|
# initialize parameters
|
||
|
|
self._init_latent_vars(n_features, dtype=X.dtype)
|
||
|
|
# change to perplexity later
|
||
|
|
last_bound = None
|
||
|
|
n_jobs = effective_n_jobs(self.n_jobs)
|
||
|
|
with Parallel(n_jobs=n_jobs, verbose=max(0, self.verbose - 1)) as parallel:
|
||
|
|
for i in range(max_iter):
|
||
|
|
if learning_method == "online":
|
||
|
|
for idx_slice in gen_batches(n_samples, batch_size):
|
||
|
|
self._em_step(
|
||
|
|
X[idx_slice, :],
|
||
|
|
total_samples=n_samples,
|
||
|
|
batch_update=False,
|
||
|
|
parallel=parallel,
|
||
|
|
)
|
||
|
|
else:
|
||
|
|
# batch update
|
||
|
|
self._em_step(
|
||
|
|
X, total_samples=n_samples, batch_update=True, parallel=parallel
|
||
|
|
)
|
||
|
|
|
||
|
|
# check perplexity
|
||
|
|
if evaluate_every > 0 and (i + 1) % evaluate_every == 0:
|
||
|
|
doc_topics_distr, _ = self._e_step(
|
||
|
|
X, cal_sstats=False, random_init=False, parallel=parallel
|
||
|
|
)
|
||
|
|
bound = self._perplexity_precomp_distr(
|
||
|
|
X, doc_topics_distr, sub_sampling=False
|
||
|
|
)
|
||
|
|
if self.verbose:
|
||
|
|
print(
|
||
|
|
"iteration: %d of max_iter: %d, perplexity: %.4f"
|
||
|
|
% (i + 1, max_iter, bound)
|
||
|
|
)
|
||
|
|
|
||
|
|
if last_bound and abs(last_bound - bound) < self.perp_tol:
|
||
|
|
break
|
||
|
|
last_bound = bound
|
||
|
|
|
||
|
|
elif self.verbose:
|
||
|
|
print("iteration: %d of max_iter: %d" % (i + 1, max_iter))
|
||
|
|
self.n_iter_ += 1
|
||
|
|
|
||
|
|
# calculate final perplexity value on train set
|
||
|
|
doc_topics_distr, _ = self._e_step(
|
||
|
|
X, cal_sstats=False, random_init=False, parallel=parallel
|
||
|
|
)
|
||
|
|
self.bound_ = self._perplexity_precomp_distr(
|
||
|
|
X, doc_topics_distr, sub_sampling=False
|
||
|
|
)
|
||
|
|
|
||
|
|
return self
|
||
|
|
|
||
|
|
def _unnormalized_transform(self, X):
|
||
|
|
"""Transform data X according to fitted model.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
doc_topic_distr : ndarray of shape (n_samples, n_components)
|
||
|
|
Document topic distribution for X.
|
||
|
|
"""
|
||
|
|
doc_topic_distr, _ = self._e_step(X, cal_sstats=False, random_init=False)
|
||
|
|
|
||
|
|
return doc_topic_distr
|
||
|
|
|
||
|
|
def transform(self, X):
|
||
|
|
"""Transform data X according to the fitted model.
|
||
|
|
|
||
|
|
.. versionchanged:: 0.18
|
||
|
|
*doc_topic_distr* is now normalized
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
doc_topic_distr : ndarray of shape (n_samples, n_components)
|
||
|
|
Document topic distribution for X.
|
||
|
|
"""
|
||
|
|
check_is_fitted(self)
|
||
|
|
X = self._check_non_neg_array(
|
||
|
|
X, reset_n_features=False, whom="LatentDirichletAllocation.transform"
|
||
|
|
)
|
||
|
|
doc_topic_distr = self._unnormalized_transform(X)
|
||
|
|
doc_topic_distr /= doc_topic_distr.sum(axis=1)[:, np.newaxis]
|
||
|
|
return doc_topic_distr
|
||
|
|
|
||
|
|
def _approx_bound(self, X, doc_topic_distr, sub_sampling):
|
||
|
|
"""Estimate the variational bound.
|
||
|
|
|
||
|
|
Estimate the variational bound over "all documents" using only the
|
||
|
|
documents passed in as X. Since log-likelihood of each word cannot
|
||
|
|
be computed directly, we use this bound to estimate it.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
doc_topic_distr : ndarray of shape (n_samples, n_components)
|
||
|
|
Document topic distribution. In the literature, this is called
|
||
|
|
gamma.
|
||
|
|
|
||
|
|
sub_sampling : bool, default=False
|
||
|
|
Compensate for subsampling of documents.
|
||
|
|
It is used in calculate bound in online learning.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
score : float
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def _loglikelihood(prior, distr, dirichlet_distr, size):
|
||
|
|
# calculate log-likelihood
|
||
|
|
score = np.sum((prior - distr) * dirichlet_distr)
|
||
|
|
score += np.sum(gammaln(distr) - gammaln(prior))
|
||
|
|
score += np.sum(gammaln(prior * size) - gammaln(np.sum(distr, 1)))
|
||
|
|
return score
|
||
|
|
|
||
|
|
is_sparse_x = sp.issparse(X)
|
||
|
|
n_samples, n_components = doc_topic_distr.shape
|
||
|
|
n_features = self.components_.shape[1]
|
||
|
|
score = 0
|
||
|
|
|
||
|
|
dirichlet_doc_topic = _dirichlet_expectation_2d(doc_topic_distr)
|
||
|
|
dirichlet_component_ = _dirichlet_expectation_2d(self.components_)
|
||
|
|
doc_topic_prior = self.doc_topic_prior_
|
||
|
|
topic_word_prior = self.topic_word_prior_
|
||
|
|
|
||
|
|
if is_sparse_x:
|
||
|
|
X_data = X.data
|
||
|
|
X_indices = X.indices
|
||
|
|
X_indptr = X.indptr
|
||
|
|
|
||
|
|
# E[log p(docs | theta, beta)]
|
||
|
|
for idx_d in range(0, n_samples):
|
||
|
|
if is_sparse_x:
|
||
|
|
ids = X_indices[X_indptr[idx_d] : X_indptr[idx_d + 1]]
|
||
|
|
cnts = X_data[X_indptr[idx_d] : X_indptr[idx_d + 1]]
|
||
|
|
else:
|
||
|
|
ids = np.nonzero(X[idx_d, :])[0]
|
||
|
|
cnts = X[idx_d, ids]
|
||
|
|
temp = (
|
||
|
|
dirichlet_doc_topic[idx_d, :, np.newaxis] + dirichlet_component_[:, ids]
|
||
|
|
)
|
||
|
|
norm_phi = logsumexp(temp, axis=0)
|
||
|
|
score += np.dot(cnts, norm_phi)
|
||
|
|
|
||
|
|
# compute E[log p(theta | alpha) - log q(theta | gamma)]
|
||
|
|
score += _loglikelihood(
|
||
|
|
doc_topic_prior, doc_topic_distr, dirichlet_doc_topic, self.n_components
|
||
|
|
)
|
||
|
|
|
||
|
|
# Compensate for the subsampling of the population of documents
|
||
|
|
if sub_sampling:
|
||
|
|
doc_ratio = float(self.total_samples) / n_samples
|
||
|
|
score *= doc_ratio
|
||
|
|
|
||
|
|
# E[log p(beta | eta) - log q (beta | lambda)]
|
||
|
|
score += _loglikelihood(
|
||
|
|
topic_word_prior, self.components_, dirichlet_component_, n_features
|
||
|
|
)
|
||
|
|
|
||
|
|
return score
|
||
|
|
|
||
|
|
def score(self, X, y=None):
|
||
|
|
"""Calculate approximate log-likelihood as score.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
y : Ignored
|
||
|
|
Not used, present here for API consistency by convention.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
score : float
|
||
|
|
Use approximate bound as score.
|
||
|
|
"""
|
||
|
|
check_is_fitted(self)
|
||
|
|
X = self._check_non_neg_array(
|
||
|
|
X, reset_n_features=False, whom="LatentDirichletAllocation.score"
|
||
|
|
)
|
||
|
|
|
||
|
|
doc_topic_distr = self._unnormalized_transform(X)
|
||
|
|
score = self._approx_bound(X, doc_topic_distr, sub_sampling=False)
|
||
|
|
return score
|
||
|
|
|
||
|
|
def _perplexity_precomp_distr(self, X, doc_topic_distr=None, sub_sampling=False):
|
||
|
|
"""Calculate approximate perplexity for data X with ability to accept
|
||
|
|
precomputed doc_topic_distr
|
||
|
|
|
||
|
|
Perplexity is defined as exp(-1. * log-likelihood per word)
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
doc_topic_distr : ndarray of shape (n_samples, n_components), \
|
||
|
|
default=None
|
||
|
|
Document topic distribution.
|
||
|
|
If it is None, it will be generated by applying transform on X.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
score : float
|
||
|
|
Perplexity score.
|
||
|
|
"""
|
||
|
|
if doc_topic_distr is None:
|
||
|
|
doc_topic_distr = self._unnormalized_transform(X)
|
||
|
|
else:
|
||
|
|
n_samples, n_components = doc_topic_distr.shape
|
||
|
|
if n_samples != X.shape[0]:
|
||
|
|
raise ValueError(
|
||
|
|
"Number of samples in X and doc_topic_distr do not match."
|
||
|
|
)
|
||
|
|
|
||
|
|
if n_components != self.n_components:
|
||
|
|
raise ValueError("Number of topics does not match.")
|
||
|
|
|
||
|
|
current_samples = X.shape[0]
|
||
|
|
bound = self._approx_bound(X, doc_topic_distr, sub_sampling)
|
||
|
|
|
||
|
|
if sub_sampling:
|
||
|
|
word_cnt = X.sum() * (float(self.total_samples) / current_samples)
|
||
|
|
else:
|
||
|
|
word_cnt = X.sum()
|
||
|
|
perword_bound = bound / word_cnt
|
||
|
|
|
||
|
|
return np.exp(-1.0 * perword_bound)
|
||
|
|
|
||
|
|
def perplexity(self, X, sub_sampling=False):
|
||
|
|
"""Calculate approximate perplexity for data X.
|
||
|
|
|
||
|
|
Perplexity is defined as exp(-1. * log-likelihood per word)
|
||
|
|
|
||
|
|
.. versionchanged:: 0.19
|
||
|
|
*doc_topic_distr* argument has been deprecated and is ignored
|
||
|
|
because user no longer has access to unnormalized distribution
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
X : {array-like, sparse matrix} of shape (n_samples, n_features)
|
||
|
|
Document word matrix.
|
||
|
|
|
||
|
|
sub_sampling : bool
|
||
|
|
Do sub-sampling or not.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
score : float
|
||
|
|
Perplexity score.
|
||
|
|
"""
|
||
|
|
check_is_fitted(self)
|
||
|
|
X = self._check_non_neg_array(
|
||
|
|
X, reset_n_features=True, whom="LatentDirichletAllocation.perplexity"
|
||
|
|
)
|
||
|
|
return self._perplexity_precomp_distr(X, sub_sampling=sub_sampling)
|
||
|
|
|
||
|
|
@property
|
||
|
|
def _n_features_out(self):
|
||
|
|
"""Number of transformed output features."""
|
||
|
|
return self.components_.shape[0]
|