Mercurial > cobalt-mk2 / annotate
fraction.py@032c90f1727b (annotated)
fraction.py
Tue, 02 Feb 2016 20:47:47 +0200
- author
- Teemu Piippo <crimsondusk64@gmail.com>
- date
- Tue, 02 Feb 2016 20:47:47 +0200
- changeset 167
- 032c90f1727b
- parent 164
- e18f73e4c2e2
- permissions
- -rw-r--r--
Stuff
| 164 | 1 | def gcd(a, b): |
| 2 | """ | |
| 3 | Calculate the Greatest Common Divisor of a and b. | |
| 4 | ||
| 5 | Unless b==0, the result will have the same sign as b (so that when | |
| 6 | b is divided by it, the result comes out positive). | |
| 7 | """ | |
| 8 | while b: | |
| 9 | a, b = b, a % b | |
| 10 | return a | |
| 11 | ||
| 12 | class Fraction (object): | |
| 13 | def __init__ (self, numerator, denominator = 1): | |
| 14 | if denominator == 0: | |
| 15 | raise ValueError ('Denominator may not be 0') | |
| 16 | ||
| 17 | self.numerator = int (numerator) | |
| 18 | self.denominator = int (denominator) | |
| 19 | self.simplify() | |
| 20 | ||
| 21 | @property | |
| 22 | def real (self): | |
| 23 | if self.numerator.real: | |
| 24 | return Fraction(self.numerator.real, self.denominator.real) | |
| 25 | else: | |
| 26 | return Fraction(0,1) | |
| 27 | ||
| 28 | @property | |
| 29 | def imag (self): | |
| 30 | if self.numerator.imag: | |
| 31 | return Fraction(self.numerator.imag, self.denominator.imag) | |
| 32 | else: | |
| 33 | return Fraction(0,1) | |
| 34 | ||
| 35 | def simplify (self): | |
| 36 | divisor = gcd (self.numerator, self.denominator) | |
| 37 | self.numerator //= divisor | |
| 38 | self.denominator //= divisor | |
| 39 | ||
| 40 | def __repr__ (self): | |
| 41 | return '%s(%d, %d)' % (self.__class__.__name__, self.numerator, self.denominator) | |
| 42 | ||
| 43 | def __str__ (self): | |
| 44 | if self.numerator > self.denominator: | |
| 45 | if self.numerator % self.denominator == 0: | |
| 46 | return str (self.numerator // self.denominator) | |
| 47 | else: | |
| 48 | return '%d + (%d / %d)' % (self.numerator // self.denominator, | |
| 49 | self.numerator % self.denominator, self.denominator) | |
| 50 | else: | |
| 51 | return str (self.numerator) + '/' + str (self.denominator) | |
| 52 | ||
| 53 | def __add__ (self, other): | |
| 54 | if isinstance (other, Fraction): | |
| 55 | n1, n2, d1, d2 = (self.numerator, other.numerator, self.denominator, other.denominator) | |
| 56 | return Fraction ((n1 * d2) + (n2 * d1), d1 * d2) | |
| 57 | else: | |
| 58 | return Fraction (self.numerator + (other * self.denominator), self.denominator) | |
| 59 | ||
| 60 | def __radd__ (self, other): | |
| 61 | return self + other | |
| 62 | ||
| 63 | def __sub__ (self, other): | |
| 64 | if isinstance (other, Fraction): | |
| 65 | return self.__add__ (Fraction (-other.numerator, other.denominator)) | |
| 66 | else: | |
| 67 | return self.__add__ (-other) | |
| 68 | ||
| 69 | def __rsub__ (self, other): | |
| 70 | return -self + other | |
| 71 | ||
| 72 | def __mul__ (self, other): | |
| 73 | if isinstance (other, Fraction): | |
| 74 | return Fraction (self.numerator * other.numerator, self.denominator * other.denominator) | |
| 75 | elif isinstance (other, float): | |
| 76 | return (self.numerator / self.denominator) * other | |
| 77 | elif isinstance (other, int): | |
| 78 | return Fraction (self.numerator * int (other), self.denominator) | |
| 79 | ||
| 80 | def __rmul__ (self, other): | |
| 81 | return self * other | |
| 82 | ||
| 83 | def __truediv__ (self, other): | |
| 84 | if isinstance (other, Fraction): | |
| 85 | return Fraction (self.numerator * other.denominator, self.denominator * other.numerator) | |
| 86 | else: | |
| 87 | return Fraction (self.numerator, self.denominator * int (other)) | |
| 88 | ||
| 89 | def __rtruediv__ (self, other): | |
| 90 | return other * Fraction (self.denominator, self.numerator) | |
| 91 | ||
| 92 | def __neg__ (self): | |
| 93 | return Fraction (-self.numerator, self.denominator) | |
| 94 | ||
| 95 | def __abs__ (self): | |
| 96 | return Fraction (abs (self.numerator), self.denominator) |
