python中如何去除标点符号

Python去掉标点符号的方法如下：

方法一：

str.isalnum：

S.isalnum() -> bool

返回值：如果string至少有一个字符并且所有字符都是字母或数字则返回True,否则返回False。

实例:

>>> string = "Special $#! characters   spaces 888323">>> ''.join(e for e in string if e.isalnum())'Specialcharactersspaces888323'

只能识别字母和数字，杀伤力大，会把中文、空格之类的也干掉

方法二：

string.punctuation

import re, strings ="string. With. Punctuation?" # Sample string # 写法一：out = s.translate(string.maketrans("",""), string.punctuation)# 写法二：out = s.translate(None, string.punctuation)# 写法三：exclude = set(string.punctuation)out = ''.join(ch for ch in s if ch not in exclude)# 写法四：>>> for c in string.punctuation:			s = s.replace(c,"")>>> s'string With Punctuation'# 写法五：out = re.sub('[%s]' % re.escape(string.punctuation), '', s)## re.escape:对字符串中所有可能被解释为正则运算符的字符进行转义# 写法六：# string.punctuation 只包括 ascii 格式； 想要一个包含更广（但是更慢）的方法是使用： unicodedata module :from unicodedata import categorys = u&#3<p style="color:transparent">本文来源gao!%daima.com搞$代*!码$网3</p>9;String — with - «Punctuation »...'out = re.sub('[%s]' % re.escape(string.punctuation), '', s)print 'Stripped', out# 输出：u'Stripped String \u2014 with  \xabPunctuation \xbb'out = ''.join(ch for ch in s if category(ch)[0] != 'P')print 'Stripped', out# 输出：u'Stripped String  with  Punctuation '# For Python 3 str or Python 2 unicode values, str.translate() only takes a dictionary; codepoints (integers) are looked up in that mapping and anything mapped to None is removed.# To remove (some?) punctuation then, use:import stringremove_punct_map = dict.fromkeys(map(ord, string.punctuation))s.translate(remove_punct_map)# Your method doesn't work in Python 3, as the translate method doesn't accept the second argument any more. import unicodedataimport systbl = dict.fromkeys(i for i in range(sys.maxunicode) if unicodedata.category(chr(i)).startswith('P'))def remove_punctuation(text):	return text.translate(tbl)

方法三：

re

例：

import res ="string. With. Punctuation?"s = re.sub(r'[^\w\s]','',s)

测试：

import re, string, timeits ="string. With. Punctuation"exclude = set(string.punctuation)table = string.maketrans("","")regex = re.compile('[%s]' % re.escape(string.punctuation))def test_set(s):	return ''.join(ch for ch in s if ch not in exclude)def test_re(s): 	return regex.sub('', s)def test_trans(s):	return s.translate(table, string.punctuation)def test_repl(s):	for c in string.punctuation:		s=s.replace(c,"")	return sprint"sets :",timeit.Timer('f(s)', 'from __main__ import s,test_set as f').timeit(1000000)print"regex :",timeit.Timer('f(s)', 'from __main__ import s,test_re as f').timeit(1000000)print"translate :",timeit.Timer('f(s)', 'from __main__ import s,test_trans as f').timeit(1000000)print"replace :",timeit.Timer('f(s)', 'from __main__ import s,test_repl as f').timeit(1000000)out_put:# sets : 19.8566138744# regex : 6.86155414581# translate : 2.12455511093# replace : 28.4436721802

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