CODEWITHSUNDEEP
pythonwindowsfloating-pointdecimallocale
Basj
Basj

Reputation: 46433

How to make that f"..." string formatting uses comma instead of dot as decimal separator?

I tried:

import locale
print(locale.locale_alias)
locale.setlocale(locale.LC_ALL, '')
locale.setlocale(locale.LC_NUMERIC, "french")
print(f"{3.14:.2f}")

but the output is 3.14 whereas I would like 3,14.

How to do this with f"..." string formatting?

Note: I don't want to use .replace(".", ",")

Note: I'm looking for a Windows solution, and solutions from How to format a float with a comma as decimal separator in an f-string? don't work (thus it's not a duplicate on Windows):

locale.setlocale(locale.LC_ALL, 'nl_NL')
# or
locale.setlocale(locale.LC_ALL, 'fr_FR')

locale.Error: unsupported locale setting

Upvotes: 2

Views: 1528

Answers (3)

Andj
Andj

Reputation: 1374

A bit of time has elapsed after the question, but I will add an answer for future reference.

As the other answers have indicated, n will automatically pick up your locale settings (which is one of its purposes), but the precision number works differently to what you anticipate. 3.14:.2n indicated that you want 2 digits. This isn't referring to the number of decimal places in the number, but to the overall number. So decimal places will be rounded down if necessary.

f is used to control decimal precision, but does not support locale formatting. To use the f notation in a locale sensitive way, it is necessary to format the number using locale.format_string() function:

import locale
locale.setlocale(locale.LC_NUMERIC, "fr_FR.UTF-8")
print(f"{3.14:.3n}")
# 3,14
print(f"{3.14:.2n}")
# 3,1
print(f"{3.14:.1n}")
# 3
print(locale.format_string("%.2f", 3.14))
# 3,14

If you want to use n formatter, and still require decimal precision, then the round() function is an option.

print(f'{round(3.14, 2):n}')
# 3,14

Upvotes: 1

Cow
Cow

Reputation: 3030

I looked up the answers on the duplicate flagged page and found an answer that worked:

Change print(f"{3.14:.2f}") to print(f"{3.14:.3n}") and you will get the result: 3,14

See https://docs.python.org/3/library/string.html#format-specification-mini-language:

'n' Number. This is the same as 'g', except that it uses the current locale setting to insert the appropriate number separator characters.

Whereas 'g' is described at:

g General format. For a given precision p >= 1, this rounds the number to p significant digits and then formats the result in either fixed-point format or in scientific notation, depending on its magnitude. A precision of 0 is treated as equivalent to a precision of 1. ...Truncated...

The 'f' description is:

'f' Fixed-point notation. For a given precision p, formats the number as a decimal number with exactly p digits following the decimal point.

Upvotes: 4

venkat sai
venkat sai

Reputation: 11

You can use "locale.format_string" instead of "f string"

Try this instead :

import locale
# Set the locale to "french"
locale.setlocale(locale.LC_ALL, 'fr_FR.UTF-8')
# Format the number 3.14 with 2 decimal places, using the french locale
print(locale.format_string("%.2f", 3.14, grouping=True))

Upvotes: 1

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