re.sub on lists - python 3

Question

I have a list on which I try to remove special chars using a loop. When I've tried to remove those special chars without a loop, it worked. But with a loop didn't work, but did run (and I don't know how). Those special chars are :"[" and "]". It's probably something very simple or with list's comprehension, which I tried some but didn't quite work ( How do you use a regex in a list comprehension in Python? )

Could you help? I'm new to Python, but it would help a lot. Please share your knowledge!

Output should be : [ '1', '2' ]

My code:

import re
# Case 1 : Sub with no loop
w = '[ 1,2,3,4 ]'

outer= re.compile("\[(.+)\]")
m = outer.search(w)
inner_str = m.group(1)

# Case 2 - Sub with loop
x = [ '[1]', '[2]' ]

for item in x:
    if item == re.match('\[(.+)\]', item):
        print(re.sub("\[(.+)\]", "", item))

Answer 1

You can do this using a list comprehension, you mean something like this?

>>> import re
>>> x = [ '[1]', '[2]' ]
>>> [re.sub(r'\W', '', i) for i in x]
['1', '2']

The token \W matches any non-word character.

Answer 2

Assuming you are trying to keep the stuff inside the brackets, this works:

import re
# Case 1 : no sub!
w = '[ 1,2,3,4 ]'

outer= re.compile("\[(.+)\]")
m = outer.search(w)
inner_str = m.group(1)
print(inner_str)

# Case 2 - no sub!
x = [ '[1]', '[2]' ]

y = []
for item in x:
    match = outer.match(item)
    if match:
        y.append(match.group(1))

print(y)