Fraction

Fraction.py

'''
Created on Feb 11, 2012

@author: sodas
'''

class Fraction (object):
    def __init__(self, numerator, denominator):
        self.numerator = numerator
        if denominator == 0:
            raise ValueError, 'Denominoator should not be %s'%denominator
        self.denominator = denominator
        
    def refactor(self):
        def gcd(a,b):
            if b==0: return a
            else: return gcd(b, a%b)
            
        factor = gcd(self.numerator, self.denominator)
        self.numerator /= factor
        self.denominator /= factor
    
    def floatValue(self):
        return float(self.numerator)/float(self.denominator)
    
    def __str__(self):
        return '%d/%d'%(self.numerator, self.denominator)
    
    def __add__(self, other):
        n1 = self.numerator
        d1 = self.denominator
        n2 = other.numerator
        d2 = other.denominator
        
        resultN = n1*d2 + n2*d1
        resultD = d1*d2
        result = Fraction(resultN, resultD)
        result.refactor()
        return result
    
    def __sub__(self, other):
        n1 = self.numerator
        d1 = self.denominator
        n2 = other.numerator
        d2 = other.denominator
        
        resultN = n1*d2 - n2*d1
        resultD = d1*d2
        result = Fraction(resultN, resultD)
        result.refactor()
        return result
    
    def __mul__(self, other):
        n1 = self.numerator
        d1 = self.denominator
        n2 = other.numerator
        d2 = other.denominator
        
        resultN = n1*n2
        resultD = d1*d2
        result = Fraction(resultN, resultD)
        result.refactor()
        return result
    
    def __div__(self, other):
        n1 = self.numerator
        d1 = self.denominator
        n2 = other.numerator
        d2 = other.denominator
        
        resultN = n1*d2
        resultD = d1*n2
        result = Fraction(resultN, resultD)
        result.refactor()
        return result
    
    def __eq__(self, other):
        return self.numerator*other.denominator == self.denominator*other.numerator
    def __lt__(self, other):
        return self.numerator*other.denominator < self.denominator*other.numerator
    def __gt__(self, other):
        return self.numerator*other.denominator > self.denominator*other.numerator
    def __le__(self, other):
        return self.numerator*other.denominator <= self.denominator*other.numerator
    def __ge__(self, other):
        return self.numerator*other.denominator >= self.denominator*other.numerator
    
if __name__=='__main__':
    f1 = Fraction(1,3)
    f2 = Fraction(1,4)
    f3 = Fraction(1,2)
    
    try:
        f4 = Fraction(1,0)
    except ValueError,e:
        print e
        
    print f1+f2
    print f1<f2
    print f1>=f2
    print f3+f2
    print f1*f2
    print f1.floatValue()