在 scikit-learn 管道中使用 Word2Vec

Question

我正在尝试对这个数据样本运行 w2v

Statement              Label
Says the Annies List political group supports third-trimester abortions on demand.       FALSE
When did the decline of coal start? It started when natural gas took off that started to begin in (President George W.) Bushs administration.         TRUE
"Hillary Clinton agrees with John McCain ""by voting to give George Bush the benefit of the doubt on Iran."""     TRUE
Health care reform legislation is likely to mandate free sex change surgeries.    FALSE
The economic turnaround started at the end of my term.     TRUE
The Chicago Bears have had more starting quarterbacks in the last 10 years than the total number of tenured (UW) faculty fired during the last two decades.    TRUE
Jim Dunnam has not lived in the district he represents for years now.    FALSE

使用此 GitHub 文件夹 (FeatureSelection.py) 中提供的代码：

https://github.com/nishitpatel01/Fake_News_Detection

我想在我的朴素贝叶斯模型中包含 word2vec 功能。 首先我考虑了 X 和 y 并使用了 train_test_split：

X = df['Statement']
y = df['Label']

X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=40)

dataset = pd.concat([X_train, y_train], axis=1)

这是我目前使用的代码：

#Using Word2Vec 
with open("glove.6B.50d.txt", "rb") as lines:
    w2v = {line.split()[0]: np.array(map(float, line.split()[1:]))
           for line in lines}

training_sentences = DataPrep.train_news['Statement']

model = gensim.models.Word2Vec(training_sentences, size=100) # x be tokenized text
w2v = dict(zip(model.wv.index2word, model.wv.syn0))


class MeanEmbeddingVectorizer(object):
    def __init__(self, word2vec):
        self.word2vec = word2vec
        # if a text is empty we should return a vector of zeros
        # with the same dimensionality as all the other vectors
        self.dim = len(word2vec.itervalues().next())

    def fit(self, X, y): # what are X and y?
        return self

    def transform(self, X): # should it be training_sentences?
        return np.array([
            np.mean([self.word2vec[w] for w in words if w in self.word2vec]
                    or [np.zeros(self.dim)], axis=0)
            for words in X
        ])


"""
class TfidfEmbeddingVectorizer(object):
    def __init__(self, word2vec):
        self.word2vec = word2vec
        self.word2weight = None
        self.dim = len(word2vec.itervalues().next())
    def fit(self, X, y):
        tfidf = TfidfVectorizer(analyzer=lambda x: x)
        tfidf.fit(X)
        # if a word was never seen - it must be at least as infrequent
        # as any of the known words - so the default idf is the max of 
        # known idf's
        max_idf = max(tfidf.idf_)
        self.word2weight = defaultdict(
            lambda: max_idf,
            [(w, tfidf.idf_[i]) for w, i in tfidf.vocabulary_.items()])
        return self
    def transform(self, X):
        return np.array([
                np.mean([self.word2vec[w] * self.word2weight[w]
                         for w in words if w in self.word2vec] or
                        [np.zeros(self.dim)], axis=0)
                for words in X
            ])
"""

在classifier.py中，我正在运行

nb_pipeline = Pipeline([
        ('NBCV',FeaturesSelection.w2v),
        ('nb_clf',MultinomialNB())])

但这不起作用，我收到此错误：

TypeError                                 Traceback (most recent call last)
<ipython-input-14-07045943a69c> in <module>
      2 nb_pipeline = Pipeline([
      3         ('NBCV',FeaturesSelection.w2v),
----> 4         ('nb_clf',MultinomialNB())])

/anaconda3/lib/python3.7/site-packages/sklearn/utils/validation.py in inner_f(*args, **kwargs)
     71                           FutureWarning)
     72         kwargs.update({k: arg for k, arg in zip(sig.parameters, args)})
---> 73         return f(**kwargs)
     74     return inner_f
     75 

/anaconda3/lib/python3.7/site-packages/sklearn/pipeline.py in __init__(self, steps, memory, verbose)
    112         self.memory = memory
    113         self.verbose = verbose
--> 114         self._validate_steps()
    115 
    116     def get_params(self, deep=True):

/anaconda3/lib/python3.7/site-packages/sklearn/pipeline.py in _validate_steps(self)
    160                                 "transformers and implement fit and transform "
    161                                 "or be the string 'passthrough' "
--> 162                                 "'%s' (type %s) doesn't" % (t, type(t)))
    163 
    164         # We allow last estimator to be None as an identity transformation

TypeError: All intermediate steps should be transformers and implement fit and transform or be the string 'passthrough' '{' ': array([-0.17019527,  0.32363772, -0.0770281 , -0.0278154 , -0.05182227, ....

我正在使用该文件夹中的所有程序，因此如果您使用它们，代码可以重现。

如果您能解释一下如何修复它以及需要对代码进行哪些其他更改，那就太好了。我的目标是将模型（朴素贝叶斯、随机森林等）与 BoW、TF-IDF 和 Word2Vec 进行比较。

更新：

在下面的答案（来自伊斯梅尔）之后，我将代码更新如下：

class MeanEmbeddingVectorizer(object):
    def __init__(self, word2vec, size=100):
        self.word2vec = word2vec
        self.dim = size

和

#building Linear SVM classfier
svm_pipeline = Pipeline([
        ('svmCV',FeaturesSelection_W2V.MeanEmbeddingVectorizer(FeaturesSelection_W2V.w2v)),
        ('svm_clf',svm.LinearSVC())
        ])

svm_pipeline.fit(DataPrep.train_news['Statement'], DataPrep.train_news['Label'])
predicted_svm = svm_pipeline.predict(DataPrep.test_news['Statement'])
np.mean(predicted_svm == DataPrep.test_news['Label'])

但是，我仍然遇到错误。

Answer 1

步骤 1. MultinomialNB FeaturesSelection.w2v 是一个 dict，它没有 fit 或 fit_transform 功能。 MultinomialNB 也需要非负值，所以它不起作用。所以我决定添加一个预处理阶段来规范化负值。

from sklearn.preprocessing import MinMaxScaler

nb_pipeline = Pipeline([
        ('NBCV',MeanEmbeddingVectorizer(FeatureSelection.w2v)),
        ('nb_norm', MinMaxScaler()),
        ('nb_clf',MultinomialNB())
    ])

...而不是

nb_pipeline = Pipeline([
        ('NBCV',FeatureSelection.w2v),
        ('nb_clf',MultinomialNB())
    ])

第 2 步。我在 word2vec.itervalues().next() 上遇到错误。所以我决定用与Word2Vec的大小相同的预定义来改变尺寸形状。

class MeanEmbeddingVectorizer(object):
    def __init__(self, word2vec, size=100):
        self.word2vec = word2vec
        self.dim = size

...而不是

class MeanEmbeddingVectorizer(object):
    def __init__(self, word2vec):
        self.word2vec = word2vec
        self.dim = len(word2vec.itervalues().next())