Function for remove special character from string in python

To remove special characters from a string in Python, you can use regular expressions (regex) with the 're' module. Here's an example function that removes all non-alphanumeric characters from a string:

python
import re

def remove_special_characters(s):
    return re.sub(r'\W+', '', s)

In this function, we're using the re.sub() method to substitute all non-alphanumeric characters with an empty string. The regular expression \W matches any non-word character (i.e., any character that's not a letter, digit, or underscore), and the + sign matches one or more occurrences of the previous pattern. 

You can call this function like this:

python
s = "Hello, World! How are you?" 
s = remove_special_characters(s)
print(s)  # Output: "HelloWorldHowareyou"

Note that this function removes all non-alphanumeric characters, so spaces, punctuation marks, and other special characters will be removed. If you want to preserve certain special characters, you can modify the regular expression to exclude them. For example, to keep spaces, underscores, and hyphens, you can use the following regular expression:

python
re.sub(r'[^\w\s-]', '', s)

This regular expression matches any character that's not a word character, a space, or a hyphen, and removes it from the string.