Float to str conversion without losing two decimal places and changing decimal separator

Question

In Python, I need to convert a float to string and replace the point by comma, without losing the two decimal places. I have tried several ways, but could not.

In doing:

>>> str(10.00).replace('.',',')

The return is:

'10,0'

But I need it to be:

'10,00'

Does anyone have any idea how to do this in a practical way? That is, maintaining the format pattern with two decimal places after the comma.

I thought of creating a function, which would evaluate the amount of items after the comma, and if there was one, I would concatenate with zero, if there were two decimal numbers, I would do nothing. But I believe there is a more 'intelligent' way to do this in python, maybe something similar to what is done in some databases, example: to_char(10.00, '9999999999D99').

Answer 1

If you are using IDLE may use the following code

>>> str(f'{float(10.00):.2f}').replace('.', ',')

In this case the exit will be:

'10,00'

Now if you want to implement a script you can use the following code:

n = float(input('Digite um valor real: '))
print(str(f'{n:.2f}').replace('.', ','))

OBSERVING

In the latter case the output will also be of the type string. If you ask to display the variable type the type will be displayed str.

Answer 2

One option is to use locale.format (up to Python 3.6), or locale.format_string (from Python 3.7 as in this version locale.format became deprecated):

import locale

locale.setlocale(locale.LC_ALL, 'pt_BR.utf8')
print(locale.format_string('%.2f', 10.00)) # 10,00

First I use setlocale to indicate that I want to use the locale pt_BR (Brazilian Portuguese), where the decimal separator is the comma. Then, just indicate the format %.2f, that says to format the number with two decimal places.

---

The interesting thing about this module is that it allows a greater control over formatting, which I think is more appropriate than staying replace. For example, you can also indicate whether or not you will have the thousands separator, if the value is greater than 1000:

import locale

locale.setlocale(locale.LC_ALL, 'pt_BR.utf8')

# sem separador de milhares
print(locale.format_string('%.2f', 12345.00)) # 12345,00

# com separador de milhares
print(locale.format_string('%.2f', 12345.00, True)) # 12.345,00

Besides being able to format as a monetary value (I don’t know if that was the intention):

import locale

locale.setlocale(locale.LC_ALL, 'pt_BR.utf8')

# sem separador de milhares
print(locale.currency(12345.00)) # R$ 12345,00

# com separador de milhares
print(locale.currency(12345.00, grouping=True)) # R$ 12.345,00

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The detail is that this module uses C libraries to get the format referring to the locale, according to the documentation:

The locale module is implemented on top of the _locale module, which in turn uses an ANSI C locale implementation if available.

Then the locale pt_BR must be installed/configured on the operating system for it to work. Otherwise, the alternative is to use replace even, as suggested in another answer.