replace the alphanumeric numbers with X

Another option using re is to match a word that has at least a digit and a char a-zA-Z and then replace the digits from the match with X

(?i)\b(?=[^\W\d]*\d)[\d_]*[A-Z]\w*

• (?i) Inline modifier for case insensitive (you can also use re.I on re.sub)
• \b A word boundary to prevent a partial word match
• (?=[^\W\d]*\d) Positive lookhead to assert at least a digit ( [^\W\d] is a word char without a digit )
• [\d_]*[A-Z] Match optional digits or _ and then match A-Z
• \w* Match optional word characters

Regex demo

import re

pattern = r"(?i)\b(?=[^\W\d]*\d)[\d_]*[A-Z]\w*"
text = "my text contains of the 33109 following values RT3123SO55 and also with certain numbers godwil_5708 and 323stwe and 8y9yc2 456453"

print(re.sub(pattern, lambda m: re.sub(r"\d", "X", m.group()), text))

Output

my text contains of the 33109 following values RTXXXXSOXX and also with certain numbers godwil_XXXX and XXXstwe and XyXycX 456453

I think you could try to use PyPi's regex library instead:

\b\d+(?:\.\d+)?\b(*SKIP)(*F)|\d

See an online demo

• \b\d+(?:\.\d+)?\b - First match what we don't want. In this case I matched any 1+ digits with optional decimals inbetween word-boundaries;
• (*SKIP)(*F) - Forget what we matched and exclude it from the final results;
• | - Or;
• \d - Any single digit.

import regex as re
s = 'my text contains of the 33109 following values RT3123SO55 and also with certain numbers godwil_5708 and 323stwe and 8y9yc2 456453'
print(re.sub(r'\b\d+(?:\.\d+)?\b(*SKIP)(*F)|\d', '*', s))

Prints:

my text contains of the 33109 following values RT****SO** and also with certain numbers godwil_**** and ***stwe and *y*yc* 456453

There's probably a way to do this purely with RE. However, here's a composite approach that seems to fulfil the brief:

import re
text = "my text contains of the 33109 following values RT3123SO55 and also with certain numbers godwil_5708 and 323stwe and 8y9yc2 456453"

def replace_numbers(s):
    tokens = s.split()
    for i, t in enumerate(tokens):
        if not t.isdigit():
            tokens[i] = re.sub(r'\d', 'X', t)

    return ' '.join(tokens)

print(replace_numbers(text))

Output:

my text contains of the 33109 following values RTXXXXSOXX and also with certain numbers godwil_XXXX and XXXstwe and XyXycX 456453

Would you please try:

import re

text = 'my text contains of the 33109 following values RT3123SO55 and also with certain numbers godwil_5708 and 323stwe and 8y9yc2 456453'

s = re.sub(r'(?<=[A-Za-z_])\d+|\d+(?=[A-Za-z_])', lambda x: 'X' * len(x.group(0)), text)
print(s)

Result:

my text contains of the 33109 following values RTXXXXSOXX and also with certain numbers godwil_XXXX and XXXstwe and XyXycX 456453

You could do the following:

import re

pattern = r"\b\d+\b|(\d)"

s = "my text contains of the 33109 following values RT3123SO55 and also with certain numbers godwil_5708 and 323stwe and 8y9yc2 456453"

print(re.sub(pattern, lambda x: 'X' if x.group(1) else x.group(), s))

displays

my text contains of the 33109 following values RTXXXXSOXX and also with certain numbers godwil_XXXX and XXXstwe and XyXycX 456453

Regex demo _¯\(ツ)/¯ Code demo

If there is match of a string of digits delimited by word boundaries (\b\d+\b) nothing will be captured so the lambda's if clause evaluates false and the match is returned (leaving that part of the string unchanged); else if a single digit is matched and captured ((\d)), 'X' is returned.

Note that the order of the alternation is important: r"(\d)|\b\d+\b" will not work.