Print a big integer with punctions with Python3 string formatting mini-language

Question

I want a point after each three digits in a big number (e.g. 4.100.200.300).

>>> x = 4100200300
>>> print('{}'.format(x))
4100200300

This question is specific to Pythons string formatting mini-language.

Answer 1

There's only one available thousands separator.

The ',' option signals the use of a comma for a thousands separator.

(docs)

Example:

'{:,}'.format(x) # 4,100,200,300

If you need to use a dot as a thousand separator, consider replacing commas with '.' or setting the locale (LC_NUMERIC category) appropriately.

You could use this list to find the right locale. Note that you'll have to use the n integer presentation type for locale-aware formatting:

import locale
locale.setlocale(locale.LC_NUMERIC, 'de_DE') # or da_DK, or lt_LT, or mn_MN, or ...
'{:n}'.format(x) # 4.100.200.300

In my opinion, the former approach is much simpler:

'{:,}'.format(x).replace(',', '.') # 4.100.200.300

or

format(x, ',').replace(',', '.') # 4.100.200.300