Python（2.7）-使用re替換字符串中的多個模式

Question

我正在嘗試一種更優雅的方法，使用re替換給定字符串中的多個模式，這與一個小問題有關，即從給定字符串中刪除由兩個以上空格組成的所有子字符串，以及所有包含字母的子字符串在沒有空格的時間段后開始。 所以這句話

'This is a strange sentence.    There are too many spaces.And.Some periods are not.  placed      properly.'

應該更正為：

'This is a strange sentence.  There are too many spaces.  And.  Some periods are not.  placed properly.'

下面的我的解決方案似乎有些混亂。 我想知道是否有更好的方法，例如單行正則表達式。

def correct( astring ):

    import re
    bstring = re.sub( r'  +', ' ', astring )
    letters = [frag.strip( '.' ) for frag in re.findall( r'\.\w', bstring )]
    for letter in letters:
        bstring = re.sub( r'\.{}'.format( letter ), '.  {}'.format( letter ), bstring )
    return bstring

Answer 1

s = 'This is a strange sentence.    There are too many spaces.And.Some periods are not.  placed      properly.'

print(re.sub("\s+"," ",s).replace(".",". ").rstrip())

This is a strange sentence.  There are too many spaces. And. Some periods are not.  placed properly. 

Answer 2

您可以使用如下的re.sub函數。 除最后一個點外，這將在該點旁邊恰好添加兩個空格，並且還會用一個空格替換一個或多個空格（除了后一個點之外）。

>>> s = 'This is a strange sentence.    There are too many spaces.And.Some periods are not.  placed      properly.'
>>> re.sub(r'(?<!\.)\s+', ' ' ,re.sub(r'\.\s*(?!$)', r'.  ', s))
'This is a strange sentence.  There are too many spaces.  And.  Some periods are not.  placed properly.'

要么

>>> re.sub(r'\.\s*(?!$)', r'.  ', re.sub(r'\s+', ' ', s))
'This is a strange sentence.  There are too many spaces.  And.  Some periods are not.  placed properly.'

Answer 3

不使用任何RegEX的方法

>>> ' '.join(s.split()).replace('.','. ')[:-1]
'This is a strange sentence.  There are too many spaces. And. Some periods are not.  placed properly.'

Answer 4

什么是純正則表達式？ 像這樣？

>>> import re
>>> s = 'This is a strange sentence.    There are too many spaces.And.Some periods are not.  placed      properly.'
>>> re.sub('\s+$', '', re.sub('\s+', ' ', re.sub('\.', '. ', s)))
'This is a strange sentence. There are too many spaces. And. Some periods are not. placed properly.'