基于连词的递归组合句子

Question

我有一个句子列表，比如：

Sentence 1.
And Sentence 2.
Or Sentence 3.
New Sentence 4.
New Sentence 5.
And Sentence 6.

我试图根据“连词标准”对这些句子进行分组，这样如果下一个句子以连词开头（目前只是“and”或“or”），那么我想对它们进行分组，以便：

^{pr2}$

我写了下面的代码，它以某种方式检测到连续的句子，但不是所有的句子。在

我如何递归地编写这个代码？我试图迭代地编写它，但是有些情况下它不起作用，我无法想出如何用递归方式编写代码。在

tokens = ["Sentence 1.","And Sentence 2.","Or Sentence 3.","New Sentence 4.","New Sentence 5.","And Sentence 6."]
already_selected = []
attachlist = {}
for i in tokens:
    attachlist[i] = []

for i in range(len(tokens)):
    if i in already_selected:
        pass
    else:
        for j in range(i+1, len(tokens)):
            if j not in already_selected:
                first_word = nltk.tokenize.word_tokenize(tokens[j].lower())[0]
                if first_word in conjucture_list:
                    attachlist[tokens[i]].append(tokens[j])
                    already_selected.append(j)
                else:
                    break

Answer 1

我喜欢嵌入式迭代器和泛型，所以这里有一个超级泛型方法：

import re

class split_by:
    def __init__(self, iterable, predicate=None):
        self.iter = iter(iterable)
        self.predicate = predicate or bool

        try:
            self.head = next(self.iter)
        except StopIteration:
            self.finished = True
        else:
            self.finished = False

    def __iter__(self):
        return self

    def _section(self):
        yield self.head

        for self.head in self.iter:
            if self.predicate(self.head):
                break

            yield self.head

        else:
            self.finished = True

    def __next__(self):
        if self.finished:
            raise StopIteration

        section = self._section()
        return section

[list(x) for x in split_by(tokens, lambda sentence: not re.match("(?i)or|and", sentence))]
#>>> [['Sentence 1.', 'And Sentence 2.', 'Or Sentence 3.'], ['New Sentence 4.'], ['New Sentence 5.', 'And Sentence 6.']]

它比较长，但它是O(1)空间复杂性，并使用您选择的谓词。在