How to remove symbols from a string with Python?

Question

I'm a beginner with both Python and RegEx, and I would like to know how to make a string that takes symbols and replaces them with spaces. Any help is great.

For example:

how much for the maple syrup? $20.99? That's ricidulous!!!

into:

how much for the maple syrup 20 99 That s ridiculous

Strange this is marked as a duplicate of a question asked over a year later. — monkut, Jan 30 '14 at 00:52
My advice is to read the documentation for the [re](http://docs.python.org/library/re.html) library. It includes some pretty good examples. — Jason Baker, May 18 '09 at 02:00

score 188 · Accepted Answer · edited Jun 04 '17 at 17:59

188

One way, using regular expressions:

>>> s = "how much for the maple syrup? $20.99? That's ridiculous!!!"
>>> re.sub(r'[^\w]', ' ', s)
'how much for the maple syrup   20 99  That s ridiculous   '

\w will match alphanumeric characters and underscores
[^\w] will match anything that's not alphanumeric or underscore

edited Jun 04 '17 at 17:59

Blue Ice

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answered May 18 '09 at 01:59

dF.

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It should be noted that ^\w outside of brackets means 'match an alphanumeric character at the beginning of a line'. It's only within the brackets ( [^\w] ) that the caret symbol means 'ignore every character in here' – cmptrgeekken May 18 '09 at 02:10
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@cmptrgeekken: Thanks, fixed. – dF. May 18 '09 at 02:33
10

in stead of [^\w] you can also use \W, which is the opposite of \w. – Ikke May 18 '09 at 09:32
Infect [/\W+/g] will do the magic. – Kushal J. Apr 01 '16 at 11:28
will this work for a string containing 'é' character. whether the output will retain or remove this character? – OnePunchMan Jun 13 '19 at 13:46

monkut · Answer 2 · 2019-04-12T08:32:07.053

35

Sometimes it takes longer to figure out the regex than to just write it out in python:

import string
s = "how much for the maple syrup? $20.99? That's ricidulous!!!"
for char in string.punctuation:
    s = s.replace(char, ' ')

If you need other characters you can change it to use a white-list or extend your black-list.

Sample white-list:

whitelist = string.letters + string.digits + ' '
new_s = ''
for char in s:
    if char in whitelist:
        new_s += char
    else:
        new_s += ' '

Sample white-list using a generator-expression:

whitelist = string.letters + string.digits + ' '
new_s = ''.join(c for c in s if c in whitelist)

edited Apr 12 '19 at 08:32

answered May 18 '09 at 09:24

monkut

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I just used this whitelist method for a project I'm working on. Thanks! – Dan Gayle Nov 01 '12 at 06:01
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+1, pythonic, love it. – lwm Sep 11 '13 at 08:34

score 12 · Answer 3 · edited Jan 21 '13 at 20:31

12

I often just open the console and look for the solution in the objects methods. Quite often it's already there:

>>> a = "hello ' s"
>>> dir(a)
[ (....) 'partition', 'replace' (....)]
>>> a.replace("'", " ")
'hello   s'

Short answer: Use string.replace().

edited Jan 21 '13 at 20:31

Nathan

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answered May 18 '09 at 05:45

buster

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I think this answer is not complete looking at the problem – BugliL Sep 04 '21 at 13:51

How to remove symbols from a string with Python?

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