Trying to filter out A-Z and special characters in python-CodePudding

This is what I've tried so far:

import re
string = open('old.txt').read()
new_str = re.sub(r'[A-Z]', '', string)

characters_to_remove = '!- '
for character in characters_to_remove:
    new_str = new_str(character, '')
open('new.txt', 'w').write(new_str)

It doesn't work, can you explain why?

CodePudding user response：

Should work.

This code will check with is_alpha if the i character is an alphabetic letter (A-Z, case unsensitive) and if it returns false, will add it to the new_string variable. Later, it will check if the string contains the characters to remove.

string = open('old.txt').read()
characters_to_remove = '!- '

new_str = ''.join(i for i in string if not i.isalpha())
for c in characters_to_remove:
    new_str = new_str.replace(c, "")


open('new.txt', 'w').write(new_str)

Check information for is_alpha.

CodePudding user response：

I understand that you would like to remove every character except:

0,1,2,3,4,5,6,7,8,9
.
:

Here you go:

import re

with open(r'old.txt','r') as oldFile,open(r'new.txt', 'w') as newFile:
    newFile.write(re.sub("[^0-9.:\n] ","",oldFile.read()))