Question

我需要使用Python预处理推文。现在我想知道什么是正则表达式分别删除所有的标签，@ user和推文的链接？

例如，

original tweet: @peter I really love that shirt at #Macy. http://bet.ly//WjdiW4
- 已处理的推文：I really love that shirt at Macy
原始推文：@shawn Titanic tragedy could have been prevented Economic Times: Telegraph.co.ukTitanic tragedy could have been preve... http://bet.ly/tuN2wx
- 已处理的推文：Titanic tragedy could have been prevented Economic Times Telegraph co ukTitanic tragedy could have been preve
原始推文：I am at Starbucks http://4sh.com/samqUI (7419 3rd ave, at 75th, Brooklyn)
- 已处理的推文：I am at Starbucks 7419 3rd ave at 75th Brooklyn

我只需要每条推文中有意义的单词。我不需要用户名，任何链接或任何标点符号。

Answer 1

以下示例是近似值。不幸的是，没有正确的方法只通过正则表达式来实现。以下正则表达式只是一个URL（不仅仅是http），任何标点符号，用户名或任何非字母数字字符。它还将单词与单个空格分开。如果您想按照意图解析推文，则需要在系统中获得更多智能。考虑到没有标准的推文馈送格式，一些预知自学习算法。

这是我的建议。

' '.join(re.sub("(@[A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())

以下是您的示例

的结果

>>> x="@peter I really love that shirt at #Macy. http://bit.ly//WjdiW4"
>>> ' '.join(re.sub("(@[A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())
'I really love that shirt at Macy'
>>> x="@shawn Titanic tragedy could have been prevented Economic Times: Telegraph.co.ukTitanic tragedy could have been preve... http://bit.ly/tuN2wx"
>>> ' '.join(re.sub("(@[A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())
'Titanic tragedy could have been prevented Economic Times Telegraph co ukTitanic tragedy could have been preve'
>>> x="I am at Starbucks http://4sq.com/samqUI (7419 3rd ave, at 75th, Brooklyn) "
>>> ' '.join(re.sub("(@[A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())
'I am at Starbucks 7419 3rd ave at 75th Brooklyn'
>>>

这里有一些不完美的例子

>>> x="I c RT @iamFink: @SamanthaSpice that's my excited face and my regular face. The expression never changes."
>>> ' '.join(re.sub("(@[A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())
'I c RT that s my excited face and my regular face The expression never changes'
>>> x="RT @AstrologyForYou: #Gemini recharges through regular contact with people of like mind, and social involvement that allows expression of their ideas"
>>> ' '.join(re.sub("(@[A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())
'RT Gemini recharges through regular contact with people of like mind and social involvement that allows expression of their ideas'
>>> # Though after you add # to the regex expression filter, results become a bit better
>>> ' '.join(re.sub("([@#][A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())
'RT recharges through regular contact with people of like mind and social involvement that allows expression of their ideas'
>>> x="New comment by diego.bosca: Re: Re: wrong regular expression? http://t.co/4KOb94ua"
>>> ' '.join(re.sub("(@[A-Za-z0-9]+)|([^0-9A-Za-z \t])|(\w+:\/\/\S+)"," ",x).split())
'New comment by diego bosca Re Re wrong regular expression'
>>> #See how miserably it performed?
>>>

Answer 2

有点晚了，但这个解决方案可以防止像#hashtag1，＃hashtag2（没有空格）这样的标点符号错误，并且实现非常简单

import re,string

def strip_links(text):
    link_regex    = re.compile('((https?):((//)|(\\\\))+([\w\d:#@%/;$()~_?\+-=\\\.&](#!)?)*)', re.DOTALL)
    links         = re.findall(link_regex, text)
    for link in links:
        text = text.replace(link[0], ', ')    
    return text

def strip_all_entities(text):
    entity_prefixes = ['@','#']
    for separator in  string.punctuation:
        if separator not in entity_prefixes :
            text = text.replace(separator,' ')
    words = []
    for word in text.split():
        word = word.strip()
        if word:
            if word[0] not in entity_prefixes:
                words.append(word)
    return ' '.join(words)


tests = [
    "@peter I really love that shirt at #Macy. http://bet.ly//WjdiW4",
    "@shawn Titanic tragedy could have been prevented Economic Times: Telegraph.co.ukTitanic tragedy could have been preve... http://bet.ly/tuN2wx",
    "I am at Starbucks http://4sh.com/samqUI (7419 3rd ave, at 75th, Brooklyn)",
]
for t in tests:
    strip_all_entities(strip_links(t))


#'I really love that shirt at'
#'Titanic tragedy could have been prevented Economic Times Telegraph co ukTitanic tragedy could have been preve'
#'I am at Starbucks 7419 3rd ave at 75th Brooklyn'

Answer 3

~~这适用于您的示例。如果您的推文中包含链接，则会失败，悲惨。~~

result = re.sub(r"(?:@\S*|#\S*|http(?=.*://)\S*)", "", subject)

修改

~~也可以使用内部链接，只要它们用空格分隔。~~

请使用API。为什么重新发明轮子？

Answer 4

我知道这不是正则表达式而是：

>>>
>>> import urlparse
>>> string = '@peter I really love that shirt at #Macy. http://bit.ly//WjdiW#'
>>> new_string = ''
>>> for i in string.split():
...     s, n, p, pa, q, f = urlparse.urlparse(i)
...     if s and n:
...         pass
...     elif i[:1] == '@':
...         pass
...     elif i[:1] == '#':
...         new_string = new_string.strip() + ' ' + i[1:]
...     else:
...         new_string = new_string.strip() + ' ' + i
...
>>> new_string
'I really love that shirt at Macy.'
>>>

如何使用正则表达式删除主题标签，@ user，链接

4 个答案: