Python variable input into format string

Question

I currently have this code here:

test = 2.432
test_formatted = "{:.2f}".format(test)
print(test_formatted)

Output:

2.43

Is there a way to insert a variable for the number into the format string? Such as:

test = 2.432
te = 2
test_formatted = "{:." + str(te) + "f}".format(test)
print(test_formatted)

Thanks!

Do you mean f-strings? f"{te:.2f}" I'm not sure what your expected result is, can you explain? — zariiii9003
– zariiii9003, Commented Jun 9, 2020 at 21:06
Sorry, I misunderstood for a sec. The f string trick appears to work for me, thanks. — Macintosh Fan
– Macintosh Fan, Commented Jun 9, 2020 at 21:19

Han-Kwang Nienhuys · Accepted Answer · 2020-06-09 21:13:47Z

3

Like this:

'{{:.{}f}}'.format(te)
# Result: '{:.2f}'

Or directly convert the number with an f-string (Python 3.6 and newer):

f'{test:.{te}f}'
# Result: '2.43'

answered Jun 9, 2020 at 21:13

Han-Kwang Nienhuys

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2 Comments

Macintosh Fan Over a year ago

It prints the result but in quotes: '2.432'

Han-Kwang Nienhuys Over a year ago

Use it as the argument for print() or assign it to a variable.

nolan · Accepted Answer · 2020-06-09 21:06:58Z

2

Add some parenthesis around the string you are creating and it works!

test = 2.432
te = 3
test_formatted = ("{:." + str(te) + "f}").format(test)
print(test_formatted)

answered Jun 9, 2020 at 21:06

nolan

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1 Comment

Macintosh Fan Over a year ago

It works just fine in regular Python, but not in discord.py: discord.ext.commands.errors.CommandInvokeError: Command raised an exception: ValueError: Single '}' encountered in format string

shmulvad · Accepted Answer · 2020-06-09 21:10:03Z

1

Using f-strings, you can do something like this:

test = 2.432
te = 2
test_formatted = f"{test:.{te}f}"
print(test_formatted)

Output:

2.43

answered Jun 9, 2020 at 21:10

shmulvad

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