Regex add comma separator in number

Question

I'm trying to add comma separator to number string.

import re

s = '12 123 1234 12345 123456 1234567 12345678'
print(re.sub(r'(\d{3}\b)', r',\1', s))

# gives
# 12 ,123 1,234 12,345 123,456 12345,678

where:

123 should'nt have comma
1234567 should be 1,234,567
12345678 should be 12345,678

How about using string format? https://stackoverflow.com/questions/1823058/how-to-print-number-with-commas-as-thousands-separators — hylowaker, Feb 12 '20 at 01:38
Why should `12345678` be `12345,678`? Surely it should be `12,345,678`? — ShadowRanger, Feb 12 '20 at 02:04

score 1 · Accepted Answer · answered Feb 12 '20 at 01:44

If you insist on using re:

s = '12 123 1234 12345 123456 1234567 12345678 00111222333444555666'
s2 = ''
while s != s2:
    s2 = s
    s = re.sub(r'(\d)(\d{3}\b)', r'\1,\2', s2)
print(s)

prints

12 123 1,234 12,345 123,456 1,234,567 12,345,678 00,111,222,333,444,555,666

Regex add comma separator in number

1 Answers1