Home > Article > Backend Development > How to remove punctuation marks in python
The method of removing punctuation marks in Python is as follows:
Method 1:
str.isalnum:
S. isalnum() -> bool
Return value: True if string has at least one character and all characters are letters or numbers, otherwise False.
Example:
>>> string = "Special $#! characters spaces 888323" >>> ''.join(e for e in string if e.isalnum()) 'Specialcharactersspaces888323'
Can only recognize letters and numbers, it is very lethal and will also kill Chinese characters, spaces and the like
Method 2:
string.punctuation
import re, string s ="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 category s = u'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 string remove_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 unicodedata import sys tbl = dict.fromkeys(i for i in range(sys.maxunicode) if unicodedata.category(chr(i)).startswith('P')) def remove_punctuation(text): return text.translate(tbl)
Method 3:
re
Example:
import re s ="string. With. Punctuation?" s = re.sub(r'[^\w\s]','',s)
Test:
import re, string, timeit s ="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 s print"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
For more Python-related technical articles, please visit the Python Tutorial column to learn!
The above is the detailed content of How to remove punctuation marks in python. For more information, please follow other related articles on the PHP Chinese website!