Remove trailing special characters from string

Question

I'm trying to use a regex to clean some data before I insert the items into the database. I haven't been able to solve the issue of removing trailing special characters at the end of my strings.

How do I write this regex to only remove trailing special characters?

import re

strings = ['string01_','str_ing02_^','string03_@_', 'string04_1', 'string05_a_']

for item in strings:
  clean_this = (re.sub(r'([_+!@#$?^])', '', item))
  print (clean_this)

outputs this:
string01 # correct
string02 # incorrect because it remove _ in the string
string03 # correct
string041 # incorrect because it remove _ in the string
string05a # incorrect because it remove _ in the string and not just the trailing _

Answer 1

You could also use the special purpose rstrip method of strings

[s.rstrip('_+!@#$?^') for s in strings]
# ['string01', 'str_ing02', 'string03', 'string04_1', 'string05_a']

Answer 2

You could repeat the character class 1+ times or else only 1 special character would be replaced. Then assert the end of the string $. Note that you don't need the capturing group around the character class:

[_+!@#$?^]+$

For example:

import re
strings = ['string01_','str_ing02_^','string03_@_', 'string04_1', 'string05_a_']

for item in strings:
  clean_this = (re.sub(r'[_+!@#$?^]+$', '', item))
  print (clean_this)

See the Regex demo | Python demo

If you also want to remove whitespace characters at the end you could add \s to the character class:

[_+!@#$?^\s]+$

Regex demo