从文本中的单词索引获取字符索引

Question

给定文本中单词的索引，我需要获取字符索引。例如，在下面的文本中："The cat called other cats."单词“ cat”的索引是1。我需要cat的第一个字符的索引，即c，它将是4。我不知道这是否相关，但是我正在使用python-nltk来获取单词。现在，我能想到的唯一方法是： - Get the first character, find the number of words in this piece of text - Get the first two characters, find the number of words in this piece of text - Get the first three characters, find the number of words in this piece of text Repeat until we get to the required word.但这将是非常低效的。任何想法将不胜感激。

Answer 1

您可以在dict此处使用：

>>> import re

>>> r = re.compile(r'\w+')

>>> text = "The cat called other cats."

>>> dic = { i :(m.start(0), m.group(0)) for i, m in enumerate(r.finditer(text))}

>>> dic

{0: (0, 'The'), 1: (4, 'cat'), 2: (8, 'called'), 3: (15, 'other'), 4: (21, 'cats')}

def char_index(char, word_ind):

    start, word = dic[word_ind]

    ind = word.find(char)

    if ind != -1:

        return start + ind

...     

>>> char_index('c',1)

4

>>> char_index('c',2)

8

>>> char_index('c',3)

>>> char_index('c',4)

21