Replace strings in a list (using re.sub)

Question

I am trying to replace parts of file extensions in a list of files. I would like to be able to loop through items (files), and remove the extensions. I don't know how to appropriately loop through items in the list when re.sub as the third parameter requires a string. eg. re.sub(pattern, repl, string, count=0, flags=0)

import re

file_lst = ['cats1.fa', 'cats2.fa', 'dog1.fa', 'dog2.fa']
file_lst_trimmed =[]

for file in file_lst:
    file_lst_trimmed = re.sub(r'1.fa', '', file)

The issue arising here is that re.sub expects a string and I want it to loop through a list of strings.

Thanks for any advice!

Answer 1

You can use a list comprehension to construct the new list with the cleaned up files names. \d is the regex to match a single character and $ only matches at the end of the string.

file_lst_trimmed = [re.sub(r'\d\.fa$', '', file) for file in file_lst]

The results:

>>> file_lst_trimmed 
['cats', 'cats', 'dog', 'dog']

Answer 2

You can try this:

import re
file_lst = ['cats1.fa', 'cats2.fa', 'dog1.fa', 'dog2.fa']
final_list = [re.sub('\d+\.\w+$', '', i) for i in file_lst]

Output:

['cats', 'cats', 'dog', 'dog']