将字符串拆分为所有可能的有序短语

Question

我正在尝试探索Python内置函数的功能.我正在尝试处理一些字符串,例如:

'the fast dog'

并将字符串分解为所有可能的有序短语,如列表.上面的示例将输出如下:

[['the', 'fast dog'], ['the fast', 'dog'], ['the', 'fast', 'dog']]

关键是在生成可能的短语时需要保留字符串中单词的原始顺序.

我已经能够得到一个可以做到这一点的功能,但它相当麻烦和丑陋.但是,我想知道Python中的某些内置功能是否有用.我当时认为可以将字符串分割为各种空格,然后以递归方式应用于每个分割.可能有人有一些建议吗？

Answer 1

使用itertools.combinations:

import itertools

def break_down(text):
    words = text.split()
    ns = range(1, len(words)) # n = 1..(n-1)
    for n in ns: # split into 2, 3, 4, ..., n parts.
        for idxs in itertools.combinations(ns, n):
            yield [' '.join(words[i:j]) for i, j in zip((0,) + idxs, idxs + (None,))]

例:

>>> for x in break_down('the fast dog'):
...     print(x)
...
['the', 'fast dog']
['the fast', 'dog']
['the', 'fast', 'dog']

>>> for x in break_down('the really fast dog'):
...     print(x)
...
['the', 'really fast dog']
['the really', 'fast dog']
['the really fast', 'dog']
['the', 'really', 'fast dog']
['the', 'really fast', 'dog']
['the really', 'fast', 'dog']
['the', 'really', 'fast', 'dog']