I have the following code:

number_lookaheads = '|'.join(f'(?={number})' for number in code_network)
stationary_phone_regex  = rf'(({number_lookaheads})[d]{{8,18}})*(?=D)'
stationary_phone_matches = re.finditer(stationary_phone_regex,text_nospaces)
stationary_phone_matches = [match.group() for match in stationary_phone_matches if match.group()]

Basically what it does:

1. creates a string, of the format '(?=123)|(?=456)|(?=789)'
2. creates regex, where it matches a sequence of digits with a length between 8 and 18, if the lookahead is matched (number_lookaheads)
3. finds ind all non-overlapping matches of the regex pattern
4. creates a list of matched strings from the iterator produced by re.finditer(), without empty matches.

This code works on string without spaces.

import re

# Example list of Vorwahlen
code_network = ['123', '456', '789']  # replace with actual Vorwahlen

number_lookaheads = '|'.join(f'(?={number})' for number in code_network)
stationary_phone_regex  = rf'(({number_lookaheads})[d]{{8,18}})*(?=D)'

text = 'Some sample text with numbers like 12345678 and 43789654321 and 33333312345671333333  and 12345679'
text_nospaces = text.replace(" ", "").replace("/", "").replace("-", "").replace('(0)','')
text_nospaces += ' '

stationary_phone_matches = re.finditer(stationary_phone_regex,text_nospaces)
stationary_phone_matches = [match.group() for match in stationary_phone_matches if match.group()]
stationary_phone_matches

but unfortunately, it also extracts substrings from the string (33333312345671333333), which is not desired.

What I would like to achieve: I want to extract numbers:

• which stars from the code_network and follows stationary_phone_regex
• which starts from 43, follows by code_network and then follows stationary_phone_regex.

So in my case it should extract only:

• 12345678
• 43789654321
• 12345679

How can I do it