CSCI150/fraction.py at master · antigrl/CSCI150 · GitHub

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from fractions import gcd

class Fraction:

	def __init__(self, numerator=0, denominator=1):
		if denominator == 0:	# fraction is undefined
			self._numer = 0
			self._denom = 0
		else:
			factor = gcd( abs(numerator), abs(denominator))
			if denominator < 0:	# want to divide through by negated factor
				factor = -factor
			self._numer = numerator // factor
			self._denom = denominator // factor

########### Arithmetic Methods ##############
	def __add__(self, other):
		return Fraction(self._numer * other._denom + self._denom * other._numer,
						self._denom * other._denom)

	def __sub__(self, other):
		return Fraction(self._numer * other._denom - self._denom * other._numer,
						self._denom * other._denom)

	def __mul__(self, other):
		return Fraction(self._numer * other._numer, self._denom * other._denom)

	def __div__(self, other):
		return Fraction(self._numer * other._denom, self._denom * other._numer)

	def __neg__(self):
		return Fraction(-self._numer, self._denom)

########## Comparison Methods ###############
	def __lt__(self, other):
		return self._numer * other._denom, self._denom * other._numer

	def __eq__(self, other):
		return self._numer == other._numer and self._denom == other._denom

########## Type Conversion Methods ##########
	def __float__(self):
		return float(self._numer) / self._denom

	def __int__(self):
		return int(float(self))

	def __str__(self):
		if self._denom == 0:
			return 'Undefined'
		elif self._denom == 1:
			return str(self._numer)
		else:
			return str(self._numer) + '/' + str(self._denom)

	def invert(self):
		return Fraction(self._denom, self._numer)


# Unit Test

if __name__ == '__main__':
	fracTest = Fraction(5,9)
	reciprical = fracTest.invert()
	print reciprical