fractions

The Python fractions module provides support for rational number arithmetic. It allows you to create and manipulate fractions with numerators and denominators, enabling precise calculations without floating-point errors.

Here’s a quick example:

Python 
>>> from fractions import Fraction
>>> Fraction(1, 3) + Fraction(2, 3)  # 1/3 + 2/3
Fraction(1, 1)

Key Features

  • Creates fractions from integers, floats, and strings
  • Supports arithmetic operations with fractions
  • Provides methods for fraction manipulation and conversion

Frequently Used Classes and Functions

Object Type Description
fractions.Fraction Class Represents a rational number as a fraction
Fraction.limit_denominator() Method Finds the closest Fraction with a denominator at most a given value
Fraction.as_integer_ratio() Method Returns a tuple of two integers, whose ratio is equal to the original Fraction

Examples

Creating fractions from integers:

Python 
>>> Fraction(3, 4)
Fraction(3, 4)

Creating fractions from floats:

Python 
>>> Fraction(0.75)
Fraction(3, 4)

Creating fractions from strings:

Python 
>>> Fraction("0.75")
Fraction(3, 4)

Common Use Cases

  • Performing precise arithmetic operations with fractions
  • Converting decimal numbers to fractions
  • Simplifying fractions to their lowest terms

Real-World Example

Suppose you want to calculate the total cost of ingredients in a recipe, expressed as fractions to ensure precision when scaling:

Python 
>>> from fractions import Fraction

>>> ingredient_costs = [Fraction("1/3"), Fraction("2/5"), Fraction("1/2")]
>>> total_cost = sum(ingredient_costs)
>>> total_cost
Fraction(31, 30)

This calculation ensures that the total cost is computed accurately without rounding errors, thanks to the fractions module.