从字符串中删除标点符号的最佳方法

It seems like there should be a simpler way than:

import string
s = "string. With. Punctuation?" # Sample string 
out = s.translate(string.maketrans("",""), string.punctuation)

Is there?

From an efficiency perspective, you’re not going to beat

s.translate(None, string.punctuation)

For higher versions of Python use the following code:

s.translate(str.maketrans('', '', string.punctuation))

It’s performing raw string operations in C with a lookup table – there’s not much that will beat that but writing your own C code.

If speed isn’t a worry, another option though is:

exclude = set(string.punctuation)
s = ''.join(ch for ch in s if ch not in exclude)

This is faster than s.replace with each char, but won’t perform as well as non-pure python approaches such as regexes or string.translate, as you can see from the below timings. For this type of problem, doing it at as low a level as possible pays off.

Timing code:

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):  # From Vinko's solution, with fix.
    return regex.sub('', s)

def test_trans(s):
    return s.translate(table, string.punctuation)

def test_repl(s):  # From S.Lott's solution
    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)

This gives the following results:

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

Regular expressions are simple enough, if you know them.

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

For the convenience of usage, I sum up the note of striping punctuation from a string in both Python 2 and Python 3. Please refer to other answers for the detailed description.

Python 2

import string

s = "string. With. Punctuation?"
table = string.maketrans("","")
new_s = s.translate(table, string.punctuation)      # Output: string without punctuation

Python 3

import string

s = "string. With. Punctuation?"
table = str.maketrans(dict.fromkeys(string.punctuation))  # OR {key: None for key in string.punctuation}
new_s = s.translate(table)                          # Output: string without punctuation

myString.translate(None, string.punctuation)

I usually use something like this:

>>> s = "string. With. Punctuation?" # Sample string
>>> import string
>>> for c in string.punctuation:
...     s= s.replace(c,"")
...
>>> s
'string With Punctuation'

string.punctuation is ASCII only! A more correct (but also much slower) way is to use the unicodedata module:

# -*- coding: utf-8 -*-
from unicodedata import category
s = u'String — with -  «punctation »...'
s = ''.join(ch for ch in s if category(ch)[0] != 'P')
print 'stripped', s

You can generalize and strip other types of characters as well:

''.join(ch for ch in s if category(ch)[0] not in 'SP')

It will also strip characters like ~*+§$ which may or may not be “punctuation” depending on one’s point of view.

Not necessarily simpler, but a different way, if you are more familiar with the re family.

import re, string
s = "string. With. Punctuation?" # Sample string 
out = re.sub('[%s]' % re.escape(string.punctuation), '', s)

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)

The makes it trivial to create the mapping, setting all values to None based on the sequence of keys.

To remove all punctuation, not just ASCII punctuation, your table needs to be a little bigger; see J.F. Sebastian’s answer (Python 3 version):

import unicodedata
import sys

remove_punct_map = dict.fromkeys(i for i in range(sys.maxunicode)
                                 if unicodedata.category(chr(i)).startswith('P'))

string.punctuation misses loads of punctuation marks that are commonly used in the real world. How about a solution that works for non-ASCII punctuation?

import regex
s = u"string. With. Some・Really Weird、Non？ASCII。 「（Punctuation）」?"
remove = regex.compile(ur'[\p{C}|\p{M}|\p{P}|\p{S}|\p{Z}]+', regex.UNICODE)
remove.sub(u" ", s).strip()

Personally, I believe this is the best way to remove punctuation from a string in Python because:

• It removes all Unicode punctuation
• It’s easily modifiable, e.g. you can remove the \{S} if you want to remove punctuation, but keep symbols like $.
• You can get really specific about what you want to keep and what you want to remove, for example \{Pd} will only remove dashes.
• This regex also normalizes whitespace. It maps tabs, carriage returns, and other oddities to nice, single spaces.

This uses Unicode character properties, which you can read more about on Wikipedia.

I haven’t seen this answer yet. Just use a regex; it removes all characters besides word characters (\w) and number characters (\d), followed by a whitespace character (\s):

import re
s = "string. With. Punctuation?" # Sample string 
out = re.sub(ur'[^\w\d\s]+', '', s)

Here’s a one-liner for Python 3.5:

import string
"l*ots! o(f. p@u)n[c}t]u[a'ti\"on#$^?/".translate(str.maketrans({a:None for a in string.punctuation}))

This might not be the best solution however this is how I did it.

import string
f = lambda x: ''.join([i for i in x if i not in string.punctuation])

Here is a function I wrote. It’s not very efficient, but it is simple and you can add or remove any punctuation that you desire:

def stripPunc(wordList):
    """Strips punctuation from list of words"""
    puncList = [".",";",":","!","?","/","\\",",","#","@","$","&",")","(","\""]
    for punc in puncList:
        for word in wordList:
            wordList=[word.replace(punc,'') for word in wordList]
    return wordList

import re
s = "string. With. Punctuation?" # Sample string 
out = re.sub(r'[^a-zA-Z0-9\s]', '', s)

Just as an update, I rewrote the @Brian example in Python 3 and made changes to it to move regex compile step inside of the function. My thought here was to time every single step needed to make the function work. Perhaps you are using distributed computing and can’t have regex object shared between your workers and need to have re.compile step at each worker. Also, I was curious to time two different implementations of maketrans for Python 3

table = str.maketrans({key: None for key in string.punctuation})

vs

table = str.maketrans('', '', string.punctuation)

Plus I added another method to use set, where I take advantage of intersection function to reduce number of iterations.

This is the complete code:

import re, string, timeit

s = "string. With. Punctuation"


def test_set(s):
    exclude = set(string.punctuation)
    return ''.join(ch for ch in s if ch not in exclude)


def test_set2(s):
    _punctuation = set(string.punctuation)
    for punct in set(s).intersection(_punctuation):
        s = s.replace(punct, ' ')
    return ' '.join(s.split())


def test_re(s):  # From Vinko's solution, with fix.
    regex = re.compile('[%s]' % re.escape(string.punctuation))
    return regex.sub('', s)


def test_trans(s):
    table = str.maketrans({key: None for key in string.punctuation})
    return s.translate(table)


def test_trans2(s):
    table = str.maketrans('', '', string.punctuation)
    return(s.translate(table))


def test_repl(s):  # From S.Lott's solution
    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("sets2      :",timeit.Timer('f(s)', 'from __main__ import s,test_set2 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("translate2 :",timeit.Timer('f(s)', 'from __main__ import s,test_trans2 as f').timeit(1000000))
print("replace   :",timeit.Timer('f(s)', 'from __main__ import s,test_repl as f').timeit(1000000))

This is my results:

sets      : 3.1830138750374317
sets2      : 2.189873124472797
regex     : 7.142953420989215
translate : 4.243278483860195
translate2 : 2.427158243022859
replace   : 4.579746678471565

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


['string', 'With', 'Punctuation']

Here’s a solution without regex.

import string

input_text = "!where??and!!or$$then:)"
punctuation_replacer = string.maketrans(string.punctuation, ' '*len(string.punctuation))    
print ' '.join(input_text.translate(punctuation_replacer).split()).strip()

Output>> where and or then

• Replaces the punctuations with spaces
• Replace multiple spaces in between words with a single space
• Remove the trailing spaces, if any with strip()

A one-liner might be helpful in not very strict cases:

''.join([c for c in s if c.isalnum() or c.isspace()])

#FIRST METHOD
#Storing all punctuations in a variable    
punctuation='!?,.:;"\')(_-'
newstring='' #Creating empty string
word=raw_input("Enter string: ")
for i in word:
     if(i not in punctuation):
                  newstring+=i
print "The string without punctuation is",newstring

#SECOND METHOD
word=raw_input("Enter string: ")
punctuation='!?,.:;"\')(_-'
newstring=word.translate(None,punctuation)
print "The string without punctuation is",newstring


#Output for both methods
Enter string: hello! welcome -to_python(programming.language)??,
The string without punctuation is: hello welcome topythonprogramminglanguage

with open('one.txt','r')as myFile:

    str1=myFile.read()

    print(str1)


    punctuation = ['(', ')', '?', ':', ';', ',', '.', '!', '/', '"', "'"] 

for i in punctuation:

        str1 = str1.replace(i," ") 
        myList=[]
        myList.extend(str1.split(" "))
print (str1) 
for i in myList:

    print(i,end='\n')
    print ("____________")

Why none of you use this?

 ''.join(filter(str.isalnum, s)) 

Too slow?

Considering unicode. Code checked in python3.

from unicodedata import category
text = 'hi, how are you?'
text_without_punc = ''.join(ch for ch in text if not category(ch).startswith('P'))

Remove stop words from the text file using Python

print('====THIS IS HOW TO REMOVE STOP WORS====')

with open('one.txt','r')as myFile:

    str1=myFile.read()

    stop_words ="not", "is", "it", "By","between","This","By","A","when","And","up","Then","was","by","It","If","can","an","he","This","or","And","a","i","it","am","at","on","in","of","to","is","so","too","my","the","and","but","are","very","here","even","from","them","then","than","this","that","though","be","But","these"

    myList=[]

    myList.extend(str1.split(" "))

    for i in myList:

        if i not in stop_words:

            print ("____________")

            print(i,end='\n')

I like to use a function like this:

def scrub(abc):
    while abc[-1] is in list(string.punctuation):
        abc=abc[:-1]
    while abc[0] is in list(string.punctuation):
        abc=abc[1:]
    return abc