How to remove punctuation marks in python-Python Tutorial-php.cn

How to remove punctuation marks in python

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Release： 2019-07-01 09:34:40

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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"
>>> &#39;&#39;.join(e for e in string if e.isalnum())
&#39;Specialcharactersspaces888323&#39;

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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 = &#39;&#39;.join(ch for ch in s if ch not in exclude)

# 写法四：
>>> for c in string.punctuation:
			s = s.replace(c,"")
>>> s
&#39;string With Punctuation&#39;

# 写法五：
out = re.sub(&#39;[%s]&#39; % re.escape(string.punctuation), &#39;&#39;, 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&#39;String — with - «Punctuation »...&#39;
out = re.sub(&#39;[%s]&#39; % re.escape(string.punctuation), &#39;&#39;, s)
print &#39;Stripped&#39;, out
# 输出：u&#39;Stripped String \u2014 with  \xabPunctuation \xbb&#39;
out = &#39;&#39;.join(ch for ch in s if category(ch)[0] != &#39;P&#39;)
print &#39;Stripped&#39;, out
# 输出：u&#39;Stripped String  with  Punctuation &#39;


# 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&#39;t work in Python 3, as the translate method doesn&#39;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(&#39;P&#39;))
def remove_punctuation(text):
	return text.translate(tbl)

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Method 3:

Example:

import re
s ="string. With. Punctuation?"
s = re.sub(r&#39;[^\w\s]&#39;,&#39;&#39;,s)

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Test:

import re, string, timeit

s ="string. With. Punctuation"

exclude = set(string.punctuation)
table = string.maketrans("","")
regex = re.compile(&#39;[%s]&#39; % re.escape(string.punctuation))

def test_set(s):
	return &#39;&#39;.join(ch for ch in s if ch not in exclude)

def test_re(s): 
	return regex.sub(&#39;&#39;, 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(&#39;f(s)&#39;, &#39;from __main__ import s,test_set as f&#39;).timeit(1000000)
print"regex :",timeit.Timer(&#39;f(s)&#39;, &#39;from __main__ import s,test_re as f&#39;).timeit(1000000)
print"translate :",timeit.Timer(&#39;f(s)&#39;, &#39;from __main__ import s,test_trans as f&#39;).timeit(1000000)
print"replace :",timeit.Timer(&#39;f(s)&#39;, &#39;from __main__ import s,test_repl as f&#39;).timeit(1000000)

out_put:
# sets : 19.8566138744
# regex : 6.86155414581
# translate : 2.12455511093
# replace : 28.4436721802

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