Using f-string with format depending on a condition

Question

How can I use f-string with logic to format an int as a float? I would like if ppl is True to format num to 2 decimal places, and if ppl is False to rformat it as whatever it is.

Something like string = f'i am {num:.2f if ppl else num}' but this does not work. The below code demonstrates the behaviour that I want to achieve with a simpler f-string if possible:

ppl = True
num = 3
string = f'I am {num:.2f}' if ppl else f'I am {num}'
print(string)
#if ppl False
#=> i am 3
#if ppl True
#=> i am 3.00

Asked By: jacobcan118

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Source

Answer 1

You can nest expressions to evaluate inside expressions in an f-string. This means you can move the ternary right inside your f-string:

string = f'I am {num:{".2f" if ppl else ""}}'

Note the additional pair of braces needed for nesting.

But I don’t think this is cleaner. Personally I find it harder to parse what’s going on here, as opposed to your clear original version. After all simple is better than complex; flat is better than nested.

Answered By: Andras Deak — Слава Україні

Answer 2

I would recommend that you actually separate the fstring into two lines

num_str = f'{num:.2f}' if ppl else f'{num}'
final_str = f'I am {num_str}'

That way each line is as simple as it can be.

Answered By: Gamrix

Using f-string with format depending on a condition

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