How to replace a punctuation with a space in this code?

Question

I have this code:

 def remove_punctuation(self,text):
        exclude = set(string.punctuation)
        a=''.join(ch for ch in text if ch not in exclude)
        return ''.join(c for c in a if not ud.category(c).startswith('P'))

First I would like to know what this does :

ch for ch in text if ch not in exclude

How is it possible to write a for loop like that?

second, I want to replace those punctuation let's say in a text like this : "hello_there?my_friend!" with a space using the above code. How can I change that code to do that?

Answer 1

The piece of code:

a = ''.join([ch for ch in text if ch not in exclude])

is equivalent to

string_without_punctuation = ''
exclude = set(string.punctuation) # =set('!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~')
for character in text:
    if character not in exclude:
        string_without_punctuation += character

You could simply do this to replace the punctuation with spaces:

string_without_punctuation = ''
exclude = set(string.punctuation) # =set('!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~')
for character in text:
    if character not in exclude:
        string_without_punctuation += character
    else:
        string_without_punctuation += ' '