Question

假设我有字符串

'apples are red. this apple is green. pears are sometimes red, but not usually. pears are green. apples are yummy. lizards are green.'

我希望使用正则表达式来拉动该字符串中的句子，首先提到苹果或梨，然后是颜色，红色或绿色。所以我基本上想要一个返回的列表：

["apples are red.", "this apple is green.", "pears are sometimes red, but not usually.", pears are green."]

我可以用苹果和梨或绿色和红色来表达正则表达式，例如

re.findall(r'([^.]*?apple[^.]*|[^.]*?pear[^.]*)', string)

和

re.findall(r'([^.]*?red[^.]*|[^.]*?green[^.]*)', string)

但是当我希望水果（苹果/梨）首先出现在字符串中后跟颜色和句子后面的某个点时，我怎么把这两个放在一起呢？

Answer 1

您可以使用parentheses对子表达式进行分组：

re.findall(r"[^.]*\b(?:apple|pear)[^.]*\b(?:red|green)\b[^.]*\.", string)

例如：

>>> import re
>>> a = 'apples are red. this apple is green. pears are sometimes red, but not usually. pears are green. apples are yummy. lizards are green.'
>>> re.findall(r"[^.]*\b(?:apple|pear)[^.]*\b(?:red|green)\b[^.]*\.", a)
['apples are red.', ' this apple is green.', 
 ' pears are sometimes red, but not usually.', ' pears are green.']

Answer 2

使用此模式(?:^|\b)(?=[^.]*(?:apple|pear)[^.]*(?:red|green))([^.]+\.) Demo

Answer 3

我建议你阅读NLTK（自然语言工具包）。它是用于文本处理的python包

使用正则表达式在python中使用关键字组合来拉动句子

3 个答案: