如何在python和NLTK中计算预测概率? [英] How to calculate prediction probability in python and NLTK?

问题描述

我试图通过使用LinearSVC和OneVsRestClassifier来计算SVM模型中的每个预测概率，但是会出现错误

I am trying to calculate each prediction probability in SVM model by using LinearSVC and OneVsRestClassifier but getting the error

AttributeError: 'LinearSVC' object has no attribute 'predict_proba'

尝试的代码:

model = Pipeline([('vectorizer', CountVectorizer(ngram_range=(1,2))),
    ('tfidf', TfidfTransformer(use_idf=True)),
    ('clf', OneVsRestClassifier(LinearSVC(class_weight="balanced")))])

model.fit(X_train, y_train)
y_train.shape
pred = model.predict(X_test)

probas = model.predict_proba(X_test)

也尝试过:

from nltk.classify.scikitlearn import SklearnClassifier
from sklearn.svm import SVC

LinearSVC_classifier = SklearnClassifier(SVC(kernel='linear',probability=True))
prob_1 = LinearSVC_classifier.predict_proba(X_test)

但仍然出现错误AttributeError: 'SklearnClassifier' object has no attribute 'predict_proba'

请提出相同的建议.

推荐答案

使用线性SVM:

from sklearn.calibration import CalibratedClassifierCV
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.pipeline import FeatureUnion, make_pipeline
from sklearn.svm import LinearSVC

word_vectorizer = TfidfVectorizer(ngram_range=(1, 2))
features = FeatureUnion([('words', word_vectorizer), ])
calibrated_svc = CalibratedClassifierCV(LinearSVC(), method='sigmoid', cv=3)
pipeline = make_pipeline(features, calibrated_svc)
pipeline.fit(train_x, train_y)
predicted = pipeline.predict_proba(test_x)

或具有Logistic回归:

or with Logistic Regression:

from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.pipeline import FeatureUnion, make_pipeline
from sklearn.linear_model import LogisticRegression

word_vectorizer = TfidfVectorizer(ngram_range=(1, 2))
features = FeatureUnion([('words', word_vectorizer), ])
pipeline = make_pipeline(features, LogisticRegression())
pipeline.fit(train_x, train_y)
predicted = pipeline.predict_proba(test_x)

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