Find an alternating (letter or number) + letter pattern in a file name

Question

From the following list of filenames I am trying to retrieve the highlighted parts:

• something something Ah6d8c.txt
• something Qd6h7s.txt
• somethingAcKhJssomething.txt
• 7h6c8c something.txt

The pattern is:

• 6 characters long
• starts with 2-9 or A K Q J T, both lower and uppercase
• the second character is always h s c d, both lower and uppercase
• the third and fourth match the first and second
• same for the fifth and sixth

import os
import re

root = "C:/root"
data = dict()

re_pattern = "[a-zA-Z|2-9][h|s|c|d][a-zA-Z|2-9][h|s|c|d][a-zA-Z|2-9][h|s|c|d]"

for folder in os.listdir(root):
    data[folder] = dict()
    for item in os.listdir(f"{root}/{folder}"):
        board_id = re.findall(item, re_pattern)
        print(board_id)
        data[folder][item] = f"{root}/{folder}/{item}"

I thought my regex would work but it finds an empty list. Is my regex or my code wrong? The goal is to have the board_id be the dictionary key and the value the entire path.

EDIT Improved pattern looks like:

import os
import re

root = "C:/root"
data = dict()

re_pattern = "(?i)(?:[2-9AJKQT][hscd]){3}"

for folder in os.listdir(root):
    data[folder] = dict()
    for item in os.listdir(f"{root}/{folder}"):
        board_id = re.search(item, re_pattern)
        print(f"{item} :: {board_id}")
        data[folder][item] = f"{root}/{folder}/{item}"

Results are still not right, must be in the code instead:

• As6d5d BTN 2.5x vs BB.txt :: None
• SRP 3x 5h6d3c.txt :: None

Best regards

Answer 1

How about using character classes in a quantified group.

(?i)(?:[2-9AJKQT][hscd]){3}

See this demo at regex101 or this Python demo

For caseless matching use (?i) flag or re.IGNORECASE.

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Taking a closer look at your code, further be aware of order, arguments are passed in re.findall

 re.findall(pattern, string, flags=0)

Another idea for future, it might further be, to consider generally using raw string notation for regex patterns but this is not an issue with your current pattern.