NLP之NB&GBT：基于朴素贝叶斯(count/tfidf+网格搜索+4fCrva)、梯度提升树(w2c+网格搜索+4fCrva)算法对IMDB影评数据集进行文本情感分析(情感二分类预测)
NLP之NB&GBT：基于朴素贝叶斯(count/tfidf+网格搜索+4fCrva)、梯度提升树(w2c+网格搜索+4fCrva)算法对IMDB影评数据集进行文本情感分析(情感二分类预测)
数据集
排名结果
一、利用两种不同NB算法处理标注影评数据集
输出结果
submission_count.csv
submission_tfidf.csv
设计思路
核心代码
pip_count = Pipeline([('count_vec', CountVectorizer(analyzer='word')), ('mnb', MultinomialNB())])
pip_tfidf = Pipeline([('tfidf_vec', TfidfVectorizer(analyzer='word')), ('mnb', MultinomialNB())])
gs_count = GridSearchCV(pip_count, params_count, cv=4, n_jobs=-1, verbose=1)
gs_tfidf = GridSearchCV(pip_tfidf, params_tfidf, cv=4, n_jobs=-1, verbose=1)
gs_count.fit(X_train, y_train)
print('CountVectorizer：网格搜索+4fCrva得到的最佳性能：',gs_count.best_score_)
print('CountVectorizer：最优超参数组合','\n',gs_count.best_params_)
count_y_predict = gs_count.predict(X_test)
gs_tfidf.fit(X_train, y_train)
print('TfidfVectorizer：网格搜索+4fCrva得到的最佳性能：',gs_tfidf.best_score_)
print('TfidfVectorizer：最优超参数组合','\n',gs_tfidf.best_params_)
tfidf_y_predict = gs_tfidf.predict(X_test)
二、利用w2c+GB算法处理未标注影评数据集
输出结果
submission_w2v.csv
设计思路
核心代码
model = word2vec.Word2Vec(corpora, workers=num_workers, size=num_features, min_count = min_word_count, window = context, sample = downsampling)
model.init_sims(replace=True)
gbc = GradientBoostingClassifier()
params_gbc = {'n_estimators':[10, 100, 500], 'learning_rate':[0.01, 0.1, 1.0], 'max_depth': [2, 3, 4]}
gs = GridSearchCV(gbc, params_gbc, cv=4, n_jobs=-1, verbose=1)
gs.fit(trainDataVecs, y_train)
print('gbc：网格搜索+4fCrva得到的最佳性能：',gs.best_score_)
print('gbc：最优超参数组合','\n',gs.best_params_)
result = gs.predict(testDataVecs)class GradientBoostingClassifier(BaseGradientBoosting, ClassifierMixin):
"""Gradient Boosting for classification.
GB builds an additive model in a
forward stage-wise fashion; it allows for the optimization of
arbitrary differentiable loss functions. In each stage ``n_classes_``
regression trees are fit on the negative gradient of the
binomial or multinomial deviance loss function. Binary classification
is a special case where only a single regression tree is induced.
Read more in the :ref:`User Guide <gradient_boosting>`.
Parameters
----------
loss : {'deviance', 'exponential'}, optional (default='deviance')
loss function to be optimized. 'deviance' refers to
deviance (= logistic regression) for classification
with probabilistic outputs. For loss 'exponential' gradient
boosting recovers the AdaBoost algorithm.
learning_rate : float, optional (default=0.1)
learning rate shrinks the contribution of each tree by `learning_rate`.
There is a trade-off between learning_rate and n_estimators.
n_estimators : int (default=100)
The number of boosting stages to perform. Gradient boosting
is fairly robust to over-fitting so a large number usually
results in better performance.
max_depth : integer, optional (default=3)
maximum depth of the individual regression estimators. The maximum
depth limits the number of nodes in the tree. Tune this parameter
for best performance; the best value depends on the interaction
of the input variables.
criterion : string, optional (default="friedman_mse")
The function to measure the quality of a split. Supported criteria
are "friedman_mse" for the mean squared error with improvement
score by Friedman, "mse" for mean squared error, and "mae" for
the mean absolute error. The default value of "friedman_mse" is
generally the best as it can provide a better approximation in
some cases.
.. versionadded:: 0.18
min_samples_split : int, float, optional (default=2)
The minimum number of samples required to split an internal node:
- If int, then consider `min_samples_split` as the minimum number.
- If float, then `min_samples_split` is a percentage and
`ceil(min_samples_split * n_samples)` are the minimum
number of samples for each split.
.. versionchanged:: 0.18
Added float values for percentages.
min_samples_leaf : int, float, optional (default=1)
The minimum number of samples required to be at a leaf node:
- If int, then consider `min_samples_leaf` as the minimum number.
- If float, then `min_samples_leaf` is a percentage and
`ceil(min_samples_leaf * n_samples)` are the minimum
number of samples for each node.
.. versionchanged:: 0.18
Added float values for percentages.
min_weight_fraction_leaf : float, optional (default=0.)
The minimum weighted fraction of the sum total of weights (of all
the input samples) required to be at a leaf node. Samples have
equal weight when sample_weight is not provided.
subsample : float, optional (default=1.0)
The fraction of samples to be used for fitting the individual base
learners. If smaller than 1.0 this results in Stochastic Gradient
Boosting. `subsample` interacts with the parameter `n_estimators`.
Choosing `subsample < 1.0` leads to a reduction of variance
and an increase in bias.
max_features : int, float, string or None, optional (default=None)
The number of features to consider when looking for the best split:
- If int, then consider `max_features` features at each split.
- If float, then `max_features` is a percentage and
`int(max_features * n_features)` features are considered at each
split.
- If "auto", then `max_features=sqrt(n_features)`.
- If "sqrt", then `max_features=sqrt(n_features)`.
- If "log2", then `max_features=log2(n_features)`.
- If None, then `max_features=n_features`.
Choosing `max_features < n_features` leads to a reduction of variance
and an increase in bias.
Note: the search for a split does not stop until at least one
valid partition of the node samples is found, even if it requires to
effectively inspect more than ``max_features`` features.
max_leaf_nodes : int or None, optional (default=None)
Grow trees with ``max_leaf_nodes`` in best-first fashion.
Best nodes are defined as relative reduction in impurity.
If None then unlimited number of leaf nodes.
min_impurity_split : float,
Threshold for early stopping in tree growth. A node will split
if its impurity is above the threshold, otherwise it is a leaf.
.. deprecated:: 0.19
``min_impurity_split`` has been deprecated in favor of
``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
Use ``min_impurity_decrease`` instead.
min_impurity_decrease : float, optional (default=0.)
A node will be split if this split induces a decrease of the impurity
greater than or equal to this value.
The weighted impurity decrease equation is the following::
N_t / N * (impurity - N_t_R / N_t * right_impurity
- N_t_L / N_t * left_impurity)
where ``N`` is the total number of samples, ``N_t`` is the number of
samples at the current node, ``N_t_L`` is the number of samples in the
left child, and ``N_t_R`` is the number of samples in the right child.
``N``, ``N_t``, ``N_t_R`` and ``N_t_L`` all refer to the weighted sum,
if ``sample_weight`` is passed.
.. versionadded:: 0.19
init : BaseEstimator, None, optional (default=None)
An estimator object that is used to compute the initial
predictions. ``init`` has to provide ``fit`` and ``predict``.
If None it uses ``loss.init_estimator``.
verbose : int, default: 0
Enable verbose output. If 1 then it prints progress and performance
once in a while (the more trees the lower the frequency). If greater
than 1 then it prints progress and performance for every tree.
warm_start : bool, default: False
When set to ``True``, reuse the solution of the previous call to fit
and add more estimators to the ensemble, otherwise, just erase the
previous solution.
random_state : int, RandomState instance or None, optional (default=None)
If int, random_state is the seed used by the random number generator;
If RandomState instance, random_state is the random number generator;
If None, the random number generator is the RandomState instance used
by `np.random`.
presort : bool or 'auto', optional (default='auto')
Whether to presort the data to speed up the finding of best splits in
fitting. Auto mode by default will use presorting on dense data and
default to normal sorting on sparse data. Setting presort to true on
sparse data will raise an error.
.. versionadded:: 0.17
*presort* parameter.
Attributes
----------
feature_importances_ : array, shape = [n_features]
The feature importances (the higher, the more important the feature).
oob_improvement_ : array, shape = [n_estimators]
The improvement in loss (= deviance) on the out-of-bag samples
relative to the previous iteration.
``oob_improvement_[0]`` is the improvement in
loss of the first stage over the ``init`` estimator.
train_score_ : array, shape = [n_estimators]
The i-th score ``train_score_[i]`` is the deviance (= loss) of the
model at iteration ``i`` on the in-bag sample.
If ``subsample == 1`` this is the deviance on the training data.
loss_ : LossFunction
The concrete ``LossFunction`` object.
init : BaseEstimator
The estimator that provides the initial predictions.
Set via the ``init`` argument or ``loss.init_estimator``.
estimators_ : ndarray of DecisionTreeRegressor, shape = [n_estimators, ``loss_.
K``]
The collection of fitted sub-estimators. ``loss_.K`` is 1 for binary
classification, otherwise n_classes.
Notes
-----
The features are always randomly permuted at each split. Therefore,
the best found split may vary, even with the same training data and
``max_features=n_features``, if the improvement of the criterion is
identical for several splits enumerated during the search of the best
split. To obtain a deterministic behaviour during fitting,
``random_state`` has to be fixed.
See also
--------
sklearn.tree.DecisionTreeClassifier, RandomForestClassifier
AdaBoostClassifier
References
----------
J. Friedman, Greedy Function Approximation: A Gradient Boosting
Machine, The Annals of Statistics, Vol. 29, No. 5, 2001.
J. Friedman, Stochastic Gradient Boosting, 1999
T. Hastie, R. Tibshirani and J. Friedman.
Elements of Statistical Learning Ed. 2, Springer, 2009.
"""
_SUPPORTED_LOSS = 'deviance', 'exponential'
def __init__(self, loss='deviance', learning_rate=0.1, n_estimators=100,
subsample=1.0, criterion='friedman_mse', min_samples_split=2,
min_samples_leaf=1, min_weight_fraction_leaf=0.,
max_depth=3, min_impurity_decrease=0.,
min_impurity_split=None, init=None,
random_state=None, max_features=None, verbose=0,
max_leaf_nodes=None, warm_start=False,
presort='auto'):
super(GradientBoostingClassifier, self).__init__(loss=loss,
learning_rate=learning_rate, n_estimators=n_estimators, criterion=criterion,
min_samples_split=min_samples_split, min_samples_leaf=min_samples_leaf,
min_weight_fraction_leaf=min_weight_fraction_leaf, max_depth=max_depth,
init=init, subsample=subsample, max_features=max_features,
random_state=random_state, verbose=verbose,
max_leaf_nodes=max_leaf_nodes,
min_impurity_decrease=min_impurity_decrease,
min_impurity_split=min_impurity_split, warm_start=warm_start,
presort=presort)
def _validate_y(self, y):
check_classification_targets(y)
self.classes_, y = np.unique(y, return_inverse=True)
self.n_classes_ = len(self.classes_)
return y
def decision_function(self, X):
"""Compute the decision function of ``X``.
Parameters
----------
X : array-like or sparse matrix, shape = [n_samples, n_features]
The input samples. Internally, it will be converted to
``dtype=np.float32`` and if a sparse matrix is provided
to a sparse ``csr_matrix``.
Returns
-------
score : array, shape = [n_samples, n_classes] or [n_samples]
The decision function of the input samples. The order of the
classes corresponds to that in the attribute `classes_`.
Regression and binary classification produce an array of shape
[n_samples].
"""
X = check_array(X, dtype=DTYPE, order="C", accept_sparse='csr')
score = self._decision_function(X)
if score.shape[1] == 1:
return score.ravel()
return score
def staged_decision_function(self, X):
"""Compute decision function of ``X`` for each iteration.
This method allows monitoring (i.e. determine error on testing set)
after each stage.
Parameters
----------
X : array-like or sparse matrix, shape = [n_samples, n_features]
The input samples. Internally, it will be converted to
``dtype=np.float32`` and if a sparse matrix is provided
to a sparse ``csr_matrix``.
Returns
-------
score : generator of array, shape = [n_samples, k]
The decision function of the input samples. The order of the
classes corresponds to that in the attribute `classes_`.
Regression and binary classification are special cases with
``k == 1``, otherwise ``k==n_classes``.
"""
for dec in self._staged_decision_function(X):
# no yield from in Python2.X
yield dec
def predict(self, X):
"""Predict class for X.
Parameters
----------
X : array-like or sparse matrix, shape = [n_samples, n_features]
The input samples. Internally, it will be converted to
``dtype=np.float32`` and if a sparse matrix is provided
to a sparse ``csr_matrix``.
Returns
-------
y : array of shape = [n_samples]
The predicted values.
"""
score = self.decision_function(X)
decisions = self.loss_._score_to_decision(score)
return self.classes_.take(decisions, axis=0)
def staged_predict(self, X):
"""Predict class at each stage for X.
This method allows monitoring (i.e. determine error on testing set)
after each stage.
Parameters
----------
X : array-like or sparse matrix, shape = [n_samples, n_features]
The input samples. Internally, it will be converted to
``dtype=np.float32`` and if a sparse matrix is provided
to a sparse ``csr_matrix``.
Returns
-------
y : generator of array of shape = [n_samples]
The predicted value of the input samples.
"""
for score in self._staged_decision_function(X):
decisions = self.loss_._score_to_decision(score)
yield self.classes_.take(decisions, axis=0)
def predict_proba(self, X):
"""Predict class probabilities for X.
Parameters
----------
X : array-like or sparse matrix, shape = [n_samples, n_features]
The input samples. Internally, it will be converted to
``dtype=np.float32`` and if a sparse matrix is provided
to a sparse ``csr_matrix``.
Raises
------
AttributeError
If the ``loss`` does not support probabilities.
Returns
-------
p : array of shape = [n_samples]
The class probabilities of the input samples. The order of the
classes corresponds to that in the attribute `classes_`.
"""
score = self.decision_function(X)
try:
return self.loss_._score_to_proba(score)
except NotFittedError:
raise
except AttributeError:
raise AttributeError(
'loss=%r does not support predict_proba' % self.loss)
def predict_log_proba(self, X):
"""Predict class log-probabilities for X.
Parameters
----------
X : array-like or sparse matrix, shape = [n_samples, n_features]
The input samples. Internally, it will be converted to
``dtype=np.float32`` and if a sparse matrix is provided
to a sparse ``csr_matrix``.
Raises
------
AttributeError
If the ``loss`` does not support probabilities.
Returns
-------
p : array of shape = [n_samples]
The class log-probabilities of the input samples. The order of the
classes corresponds to that in the attribute `classes_`.
"""
proba = self.predict_proba(X)
return np.log(proba)
def staged_predict_proba(self, X):
"""Predict class probabilities at each stage for X.
This method allows monitoring (i.e. determine error on testing set)
after each stage.
Parameters
----------
X : array-like or sparse matrix, shape = [n_samples, n_features]
The input samples. Internally, it will be converted to
``dtype=np.float32`` and if a sparse matrix is provided
to a sparse ``csr_matrix``.
Returns
-------
y : generator of array of shape = [n_samples]
The predicted value of the input samples.
"""
try:
for score in self._staged_decision_function(X):
yield self.loss_._score_to_proba(score)
except NotFittedError:
raise
except AttributeError:
raise AttributeError(
'loss=%r does not support predict_proba' % self.loss) 赞 (0)