[精通Python自然语言处理] Ch1 - 将句子切分为单词

实验对比了一下三种切分方式：

1,2 : nltk.word_tokenize :  分离缩略词，(“Don't” =>'Do', "n't"） 表句子切分的“,” "." 单独成词。

3 :  TreebankWordTokenizer: 分离缩略词， 表句子切分的 “,"单独成词，句号“.”被删去。

4 : PunktWordTokenizer: 报错： cannot import name 'PunktWordTokenizer'

5 : WordPunctTokenizer: 将标点转化为全新标识符实现切分。(“Don't” =>'Don', "'", 't')

 import nltk
 text = "We're excited to let you know that. Harry, 18 years old, will join us on Nov. 29. Don't tell him."

 text_tokenized = nltk.word_tokenize(text)
 print("1: word_tokenize:", text_tokenized)
 print("length: ", len(text_tokenized))

 from nltk import word_tokenize
 text_tokenized_2 = word_tokenize(text)
 print("2: word_tokenize:", text_tokenized_2)
 print("length: ", len(text_tokenized_2))

 from nltk.tokenize import TreebankWordTokenizer
 tokenizer3 = TreebankWordTokenizer()
 text_tokenized_3 = tokenizer3.tokenize(text)
 print("3: TreebankWordTokenizer", text_tokenized_3)
 print("length: ", len(text_tokenized_3))

 # from nltk.tokenize import PunktWordTokenizer
 # tokenizer4 = PunktWordTokenizer()
 # text_tokenized_4 = tokenizer4.tokenize(text)
 # print("4: PunktWordTokenizer", text_tokenized_4)
 # print("length: ", len(text_tokenized_4))

 from nltk.tokenize import WordPunctTokenizer
 tokenizer5 = WordPunctTokenizer()
 text_tokenized_5 = tokenizer5.tokenize(text)
 print("5: WordPunctTokenizer", text_tokenized_5)
 print("length: ", len(text_tokenized_5))

输出：

 : word_tokenize: ['We', "'re", 'excited', 'to', 'let', 'you', 'know', 'that', '.', 'Harry', ',', '', 'years', 'old', ',', 'will', 'join', 'us', 'on', 'Nov.', '', '.', 'Do', "n't", 'tell', 'him', '.']
 length:
 : word_tokenize: ['We', "'re", 'excited', 'to', 'let', 'you', 'know', 'that', '.', 'Harry', ',', '', 'years', 'old', ',', 'will', 'join', 'us', 'on', 'Nov.', '', '.', 'Do', "n't", 'tell', 'him', '.']
 length:
 : TreebankWordTokenizer ['We', "'re", 'excited', 'to', 'let', 'you', 'know', 'that.', 'Harry', ',', '', 'years', 'old', ',', 'will', 'join', 'us', 'on', 'Nov.', '29.', 'Do', "n't", 'tell', 'him', '.']
 length:
 : WordPunctTokenizer ['We', "'", 're', 'excited', 'to', 'let', 'you', 'know', 'that', '.', 'Harry', ',', '', 'years', 'old', ',', 'will', 'join', 'us', 'on', 'Nov', '.', '', '.', 'Don', "'", 't', 'tell', 'him', '.']
 length: