How can I print a float with thousands separators?

Question

How can I format a decimal number so that 32757121.33 will display as 32.757.121,33?

Answer 1

If you can't or don't want to use locale for some reason, you can also do it with a regular expression:

import re
def sep(s, thou=",", dec="."):
    integer, decimal = s.split(".")
    integer = re.sub(r"\B(?=(?:\d{3})+$)", thou, integer)
    return integer + dec + decimal

sep() takes the string representation of a standard Python float and returns it with custom thousands and decimal separators.

>>> s = "%.2f" % 32757121.33
>>> sep(s)
'32,757,121.33'
>>> sep(s, thou=".", dec=",")
'32.757.121,33'

Explanation:

\B      # Assert that we're not at the start of the number
(?=     # Match at a position where it's possible to match...
 (?:    #  the following regex:
  \d{3} #   3 digits
 )+     #  repeated at least once
 $      #  until the end of the string
)       # (thereby ensuring a number of digits divisible by 3