Table of Contents

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Basics

Let's define some dummy variables:

pi = 3.141592653589
answer = 42
heads_or_tails = .5

The most standard thing to do is adding spaces before or after:

print(f'pi is: {my_var}')
print(f'pi is: |{my_var:->20}|')

The syntax is as follow: variable : optional[separator] optional[align-operator] optional[number_of_characters]

• separator: any character. Default is an empty space
• align-operator:
< : left
> : right
^ : center
• number_of_characters: int

Example:

print(f'answer is: |{answer:->20}|')
>>> answer is: |------------------42|

Data types

You can format your variable based on their type and how you want to represent them

letter	data type	example	result
s	string
f	floating point number (default: 6 digits)	print(f'pi is: {pi:.2f}')	pi is: 3.14
b	binary	print(f'answer is: {answer:b}')	answer is: 101010
o	octal	print(f'answer is: {answer:o}')	answer is: 52
x	hexadecimal	print(f'answer is: {answer:x}')	answer is: 2a
X	HEXADECIMAL	print(f'answer is: {answer:X}')	answer is: 2A
d	decimal	print(f'answer is: {answer:d}')	answer is: 42
n	number	print(f'pi is: {pi:n}')	pi is: 3.14159
e	exponent	print(f'pi is: {pi:e}')	pi is: 3.141593e+00
%	percentage. Multiply by 100 and adds a % sign	print(f'chances are: {heads_or_tails:.2%}')	chances are: 50.00%

Combinations

print(f'chances are: |{heads_or_tails:-^20%}|')
>>> chances are: |-----50.000000%-----|

print(f'pi x 1000 is: |{pi*1e4:,.2f}|')
>>> pi x 1000 is: |31,415.93|

print(f'pi x 1000 is: |{pi*1e4:+,.2f}|')
>>> pi x 1000 is: |+31,415.93|

Create tables

print(f'Number\t\tSquare\t\t\tCube')
for x in range(1, 4):
    x = float(x)
    print(f'{x:5.2f}\t\t{x*x:^12.2f}\t{x*x*x:.2e}')
>>>
Number      Square          Cube
 1.00           1.00        1.00e+00
 2.00           4.00        8.00e+00
 3.00           9.00        2.70e+01 

Debugging

This is available only on python 3.9+

random_operation = (42*3.1415)**0.5

print(f'{random_operation = }')
>>> random_operation = 11.486644418628098

print(f'{random_operation = :.6e}')
>>> random_operation = 1.148664e+01 

Conclusion

f-string is a powerful and ofter underestimated tool. You can take a look at this page for even more tips