Python Fractions Module
The fractions module provides support for rational number arithmetic. A Fraction instance can be constructed from a pair of integers, from another rational number, or from a string.
Importing the Module
from fractions import FractionCreating Fractions
From Integers
You can create a Fraction by passing the numerator and denominator.
from fractions import Fraction
f = Fraction(3, 4)
print(f) # Output: 3/4From Strings
print(Fraction('3/7')) # Output: 3/7
print(Fraction(' -3/7 ')) # Output: -3/7
print(Fraction('1.41421356')) # Output: 141421356/100000000From Floats
Creating a Fraction from a float can lead to unexpected results due to floating-point representation issues.
print(Fraction(1.1))
# Output: 2476979795053773/2251799813685248From Decimals
Creating from a Decimal instance usually gives the expected result.
from decimal import Decimal
print(Fraction(Decimal('1.1'))) # Output: 11/10Arithmetic Operations
Fractions support standard arithmetic operations.
a = Fraction(1, 2)
b = Fraction(1, 3)
print(a + b) # Output: 5/6
print(a - b) # Output: 1/6
print(a * b) # Output: 1/6
print(a / b) # Output: 3/2Limiting Denominator
The limit_denominator() method finds the closest rational number to a given float (or Fraction) with a denominator no larger than the argument.
import math
from fractions import Fraction
print(Fraction(math.pi).limit_denominator(10)) # Output: 22/7