rational.py: An example Python class

An instance of the Rational class represents a rational number. Mathematically:

In grade-school terms, a rational number is a fraction. Examples: 1/2; 113/355; 0/1 (which has the value zero).

In Python, you will need to import the rational module. Within this module, there is a class constructor that is invoked like this:

Rational(n, d)

where n is the numerator and d is the denominator.

This constructor returns an instance of the class, that is, an object that represents that specific rational value. Here is a conversational example:

>>> from rational import *
>>> half = Rational ( 1, 2 )
>>> print half
1/2
>>> twoSevenths = Rational ( 2, 7 )
>>> print twoSevenths * half
1/7

The above example shows that (1/2)*(2/7) equals 1/7.

The constructor will reduce values to their lowest terms:

>>> print Rational ( 50, 100 )
1/2
>>> print Rational ( 113, 355 )
113/355
>>> print Rational ( 2000, 12000 )
1/6

Operations allowed on Rational instances include:

More examples:

>>> third=Rational(1,3)
>>> fifth=Rational(1,5)
>>> print third * fifth
1/15
>>> print third + fifth
8/15
>>> print third-fifth
2/15
>>> print fifth/third
3/5
>>> print str(fifth)
1/5
>>> print float(fifth)
0.2
>>> print float(third)
0.333333333333

The module also provides one ordinary method named mixed that returns a string representing an instance as a mixed fraction. Example:

>>> badPi = Rational(22,7)
>>> print badPi.mixed()
3 and 1/7
>>> properFraction = Rational(3,5)
>>> print properFraction.mixed()
3/5
>>> wholeNum = Rational(8,2)
>>> print wholeNum
4/1
>>> print wholeNum.mixed()
4
>>> zero = Rational ( 0, 12345 )
>>> print zero.mixed()
0