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"""Abstract Base Classes (ABCs) for numbers, according to PEP 3141. |
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TODO: Fill out more detailed documentation on the operators.""" |
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from abc import ABCMeta, abstractmethod |
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__all__ = ["Number", "Complex", "Real", "Rational", "Integral"] |
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class Number(metaclass=ABCMeta): |
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"""All numbers inherit from this class. |
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If you just want to check if an argument x is a number, without |
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caring what kind, use isinstance(x, Number). |
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""" |
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__slots__ = () |
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__hash__ = None |
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class Complex(Number): |
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"""Complex defines the operations that work on the builtin complex type. |
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In short, those are: a conversion to complex, .real, .imag, +, -, |
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*, /, **, abs(), .conjugate, ==, and !=. |
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If it is given heterogeneous arguments, and doesn't have special |
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knowledge about them, it should fall back to the builtin complex |
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type as described below. |
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""" |
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__slots__ = () |
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@abstractmethod |
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def __complex__(self): |
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"""Return a builtin complex instance. Called for complex(self).""" |
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def __bool__(self): |
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"""True if self != 0. Called for bool(self).""" |
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return self != 0 |
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@property |
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@abstractmethod |
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def real(self): |
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"""Retrieve the real component of this number. |
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This should subclass Real. |
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""" |
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raise NotImplementedError |
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@property |
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@abstractmethod |
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def imag(self): |
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"""Retrieve the imaginary component of this number. |
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This should subclass Real. |
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""" |
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raise NotImplementedError |
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@abstractmethod |
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def __add__(self, other): |
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"""self + other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __radd__(self, other): |
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"""other + self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __neg__(self): |
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"""-self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __pos__(self): |
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"""+self""" |
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raise NotImplementedError |
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def __sub__(self, other): |
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"""self - other""" |
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return self + -other |
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def __rsub__(self, other): |
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"""other - self""" |
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return -self + other |
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@abstractmethod |
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def __mul__(self, other): |
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"""self * other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rmul__(self, other): |
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"""other * self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __truediv__(self, other): |
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"""self / other: Should promote to float when necessary.""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rtruediv__(self, other): |
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"""other / self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __pow__(self, exponent): |
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"""self**exponent; should promote to float or complex when necessary.""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rpow__(self, base): |
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"""base ** self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __abs__(self): |
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"""Returns the Real distance from 0. Called for abs(self).""" |
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raise NotImplementedError |
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@abstractmethod |
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def conjugate(self): |
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"""(x+y*i).conjugate() returns (x-y*i).""" |
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raise NotImplementedError |
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@abstractmethod |
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def __eq__(self, other): |
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"""self == other""" |
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raise NotImplementedError |
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Complex.register(complex) |
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class Real(Complex): |
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"""To Complex, Real adds the operations that work on real numbers. |
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In short, those are: a conversion to float, trunc(), divmod, |
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%, <, <=, >, and >=. |
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Real also provides defaults for the derived operations. |
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""" |
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__slots__ = () |
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@abstractmethod |
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def __float__(self): |
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"""Any Real can be converted to a native float object. |
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Called for float(self).""" |
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raise NotImplementedError |
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@abstractmethod |
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def __trunc__(self): |
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"""trunc(self): Truncates self to an Integral. |
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Returns an Integral i such that: |
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* i>0 iff self>0; |
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* abs(i) <= abs(self); |
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* for any Integral j satisfying the first two conditions, |
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abs(i) >= abs(j) [i.e. i has "maximal" abs among those]. |
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i.e. "truncate towards 0". |
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""" |
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raise NotImplementedError |
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@abstractmethod |
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def __floor__(self): |
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"""Finds the greatest Integral <= self.""" |
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raise NotImplementedError |
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@abstractmethod |
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def __ceil__(self): |
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"""Finds the least Integral >= self.""" |
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raise NotImplementedError |
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@abstractmethod |
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def __round__(self, ndigits=None): |
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"""Rounds self to ndigits decimal places, defaulting to 0. |
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If ndigits is omitted or None, returns an Integral, otherwise |
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returns a Real. Rounds half toward even. |
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""" |
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raise NotImplementedError |
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def __divmod__(self, other): |
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"""divmod(self, other): The pair (self // other, self % other). |
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Sometimes this can be computed faster than the pair of |
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operations. |
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""" |
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return (self // other, self % other) |
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def __rdivmod__(self, other): |
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"""divmod(other, self): The pair (self // other, self % other). |
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Sometimes this can be computed faster than the pair of |
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operations. |
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""" |
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return (other // self, other % self) |
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@abstractmethod |
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def __floordiv__(self, other): |
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"""self // other: The floor() of self/other.""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rfloordiv__(self, other): |
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"""other // self: The floor() of other/self.""" |
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raise NotImplementedError |
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@abstractmethod |
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def __mod__(self, other): |
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"""self % other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rmod__(self, other): |
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"""other % self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __lt__(self, other): |
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"""self < other |
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< on Reals defines a total ordering, except perhaps for NaN.""" |
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raise NotImplementedError |
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@abstractmethod |
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def __le__(self, other): |
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"""self <= other""" |
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raise NotImplementedError |
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def __complex__(self): |
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"""complex(self) == complex(float(self), 0)""" |
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return complex(float(self)) |
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@property |
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def real(self): |
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"""Real numbers are their real component.""" |
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return +self |
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@property |
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def imag(self): |
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"""Real numbers have no imaginary component.""" |
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return 0 |
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def conjugate(self): |
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"""Conjugate is a no-op for Reals.""" |
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return +self |
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Real.register(float) |
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class Rational(Real): |
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""".numerator and .denominator should be in lowest terms.""" |
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__slots__ = () |
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@property |
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@abstractmethod |
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def numerator(self): |
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raise NotImplementedError |
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@property |
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@abstractmethod |
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def denominator(self): |
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raise NotImplementedError |
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def __float__(self): |
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"""float(self) = self.numerator / self.denominator |
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It's important that this conversion use the integer's "true" |
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division rather than casting one side to float before dividing |
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so that ratios of huge integers convert without overflowing. |
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""" |
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return int(self.numerator) / int(self.denominator) |
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class Integral(Rational): |
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"""Integral adds methods that work on integral numbers. |
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In short, these are conversion to int, pow with modulus, and the |
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bit-string operations. |
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""" |
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__slots__ = () |
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@abstractmethod |
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def __int__(self): |
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"""int(self)""" |
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raise NotImplementedError |
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def __index__(self): |
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"""Called whenever an index is needed, such as in slicing""" |
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return int(self) |
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@abstractmethod |
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def __pow__(self, exponent, modulus=None): |
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"""self ** exponent % modulus, but maybe faster. |
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Accept the modulus argument if you want to support the |
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3-argument version of pow(). Raise a TypeError if exponent < 0 |
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or any argument isn't Integral. Otherwise, just implement the |
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2-argument version described in Complex. |
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""" |
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raise NotImplementedError |
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@abstractmethod |
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def __lshift__(self, other): |
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"""self << other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rlshift__(self, other): |
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"""other << self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rshift__(self, other): |
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"""self >> other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rrshift__(self, other): |
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"""other >> self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __and__(self, other): |
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"""self & other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rand__(self, other): |
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"""other & self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __xor__(self, other): |
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"""self ^ other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __rxor__(self, other): |
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"""other ^ self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __or__(self, other): |
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"""self | other""" |
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raise NotImplementedError |
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@abstractmethod |
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def __ror__(self, other): |
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"""other | self""" |
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raise NotImplementedError |
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@abstractmethod |
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def __invert__(self): |
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"""~self""" |
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raise NotImplementedError |
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def __float__(self): |
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"""float(self) == float(int(self))""" |
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return float(int(self)) |
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@property |
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def numerator(self): |
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"""Integers are their own numerators.""" |
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return +self |
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@property |
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def denominator(self): |
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"""Integers have a denominator of 1.""" |
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return 1 |
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Integral.register(int) |
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