Replace variable amounts of group

Question

I have the string "The dog has 12.345 bones". I want to match 12.345 and replace its . with XYZ such that the string becomes "The dog has 12XYZ345 bones". The number could be any valid number which has thousand-dots, so 1, 456, 1.000 or 34.234.233. E.g., 100.00 is not valid. How would I do that?

For internet addresses I used

address_pattern = r"(www).([A-Za-z0-9]*)\.(de|com|org)"
re.sub(address_pattern, r"\XYZ\2XYZ\3", text)

but the issue is, numbers can be as long as they want, I don't have an exact amount of groups to replace with.

user_11329890 · Answer

Use

import re
regex = r"(?


Results: The dog has 12XYZ345 bones
See Python proof. Periods are replaced inside matched numbers with lambda m: m.group().replace('.','XYZ').
EXPRESSION EXPLANATION
--------------------------------------------------------------------------------
  (?

user_298607 · Answer

If you want to actually replace . only when used as a thousands separator, you can do:

(?:<\D|^)\d{1,3}(?:\.\d{3})+(?=[^\d.]|$)

Demo

Python demo:

import re

txt='''
1
456
1.000
34.234.233
100.00
'''

print(
    re.sub(r'(?:<\D|^)\d{1,3}(?:\.\d{3})+(?=[^\d.]|$)', 
        lambda m: m.group(0).replace('.', 'XYZ'), 
        txt, flags=re.M)
)

Prints:

1
456
1XYZ000
34XYZ234XYZ233
100.00

Replace variable amounts of group

2 Answers