用于情绪分析的nltk朴素贝叶斯分类训练

Question

我正在使用语句训练Python中的NaiveBayesClassifier，它给出了下面的错误。我不知道可能是什么错误，任何帮助都是好的。

我尝试过许多其他输入格式，但错误仍然存在。代码如下：

from text.classifiers import NaiveBayesClassifier
from text.blob import TextBlob
train = [('I love this sandwich.', 'pos'),
         ('This is an amazing place!', 'pos'),
         ('I feel very good about these beers.', 'pos'),
         ('This is my best work.', 'pos'),
         ("What an awesome view", 'pos'),
         ('I do not like this restaurant', 'neg'),
         ('I am tired of this stuff.', 'neg'),
         ("I can't deal with this", 'neg'),
         ('He is my sworn enemy!', 'neg'),
         ('My boss is horrible.', 'neg') ]

test = [('The beer was good.', 'pos'),
        ('I do not enjoy my job', 'neg'),
        ("I ain't feeling dandy today.", 'neg'),
        ("I feel amazing!", 'pos'),
        ('Gary is a friend of mine.', 'pos'),
        ("I can't believe I'm doing this.", 'neg') ]
classifier = nltk.NaiveBayesClassifier.train(train)

我包括下面的回溯。

Traceback (most recent call last):
  File "C:\Users\5460\Desktop\train01.py", line 15, in <module>
    all_words = set(word.lower() for passage in train for word in word_tokenize(passage[0]))
  File "C:\Users\5460\Desktop\train01.py", line 15, in <genexpr>
    all_words = set(word.lower() for passage in train for word in word_tokenize(passage[0]))
  File "C:\Python27\lib\site-packages\nltk\tokenize\__init__.py", line 87, in word_tokenize
    return _word_tokenize(text)
  File "C:\Python27\lib\site-packages\nltk\tokenize\treebank.py", line 67, in tokenize
    text = re.sub(r'^\"', r'``', text)
  File "C:\Python27\lib\re.py", line 151, in sub
    return _compile(pattern, flags).sub(repl, string, count)
TypeError: expected string or buffer

Answer 1

你需要改变你的数据结构。这是您当前的train列表：

>>> train = [('I love this sandwich.', 'pos'),
('This is an amazing place!', 'pos'),
('I feel very good about these beers.', 'pos'),
('This is my best work.', 'pos'),
("What an awesome view", 'pos'),
('I do not like this restaurant', 'neg'),
('I am tired of this stuff.', 'neg'),
("I can't deal with this", 'neg'),
('He is my sworn enemy!', 'neg'),
('My boss is horrible.', 'neg')]

但问题是，每个元组的第一个元素应该是一个功能字典。因此，我将把您的列表更改为分类器可以使用的数据结构：

>>> from nltk.tokenize import word_tokenize # or use some other tokenizer
>>> all_words = set(word.lower() for passage in train for word in word_tokenize(passage[0]))
>>> t = [({word: (word in word_tokenize(x[0])) for word in all_words}, x[1]) for x in train]

现在，您的数据的结构应该如下所示：

>>> t
[({'this': True, 'love': True, 'deal': False, 'tired': False, 'feel': False, 'is': False, 'am': False, 'an': False, 'sandwich': True, 'ca': False, 'best': False, '!': False, 'what': False, '.': True, 'amazing': False, 'horrible': False, 'sworn': False, 'awesome': False, 'do': False, 'good': False, 'very': False, 'boss': False, 'beers': False, 'not': False, 'with': False, 'he': False, 'enemy': False, 'about': False, 'like': False, 'restaurant': False, 'these': False, 'of': False, 'work': False, "n't": False, 'i': False, 'stuff': False, 'place': False, 'my': False, 'view': False}, 'pos'), . . .]

注意，每个元组的第一个元素现在是一个字典。现在您的数据已经就位，并且每个元组的第一个元素是一个字典，您可以像这样训练分类器：

>>> import nltk
>>> classifier = nltk.NaiveBayesClassifier.train(t)
>>> classifier.show_most_informative_features()
Most Informative Features
                    this = True              neg : pos    =      2.3 : 1.0
                    this = False             pos : neg    =      1.8 : 1.0
                      an = False             neg : pos    =      1.6 : 1.0
                       . = True              pos : neg    =      1.4 : 1.0
                       . = False             neg : pos    =      1.4 : 1.0
                 awesome = False             neg : pos    =      1.2 : 1.0
                      of = False             pos : neg    =      1.2 : 1.0
                    feel = False             neg : pos    =      1.2 : 1.0
                   place = False             neg : pos    =      1.2 : 1.0
                horrible = False             pos : neg    =      1.2 : 1.0

如果你想使用分类器，你可以这样做。首先，从一个测试句子开始：

>>> test_sentence = "This is the best band I've ever heard!"

然后，标记句子并找出句子与所有单词共享的单词。这些构成了句子的特点。

>>> test_sent_features = {word: (word in word_tokenize(test_sentence.lower())) for word in all_words}

现在您的功能如下：

>>> test_sent_features
{'love': False, 'deal': False, 'tired': False, 'feel': False, 'is': True, 'am': False, 'an': False, 'sandwich': False, 'ca': False, 'best': True, '!': True, 'what': False, 'i': True, '.': False, 'amazing': False, 'horrible': False, 'sworn': False, 'awesome': False, 'do': False, 'good': False, 'very': False, 'boss': False, 'beers': False, 'not': False, 'with': False, 'he': False, 'enemy': False, 'about': False, 'like': False, 'restaurant': False, 'this': True, 'of': False, 'work': False, "n't": False, 'these': False, 'stuff': False, 'place': False, 'my': False, 'view': False}

然后，您只需对这些功能进行分类：

>>> classifier.classify(test_sent_features)
'pos' # note 'best' == True in the sentence features above

这个测试句子似乎是肯定的。