forked from M-Labs/artiq
163 lines
4.6 KiB
Python
163 lines
4.6 KiB
Python
from fractions import Fraction as _Fraction
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_prefixes_str = "pnum_kMG"
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_smallest_prefix = _Fraction(1, 10**12)
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class Unit:
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"""Represents a fundamental unit (second, hertz, ...).
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"""
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def __init__(self, name):
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self.name = name
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def __eq__(self, other):
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return isinstance(other, Unit) and self.name == other.name
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class DimensionError(Exception):
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"""Exception raised when attempting operations on incompatible units
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(e.g. adding seconds and hertz).
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"""
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pass
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class Quantity:
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"""Represents an amount in a given fundamental unit (:class:`Unit`).
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The amount can be of any Python numerical type (integer, float,
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Fraction, ...).
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Arithmetic operations and comparisons are directly delegated to the
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underlying numerical types.
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"""
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def __init__(self, amount, unit):
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self.amount = amount
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self.unit = unit
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def __repr__(self):
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r_amount = self.amount
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if isinstance(r_amount, int) or isinstance(r_amount, _Fraction):
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r_prefix = 0
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r_amount = r_amount/_smallest_prefix
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if r_amount:
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numerator = r_amount.numerator
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while numerator % 1000 == 0 and r_prefix < len(_prefixes_str):
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numerator /= 1000
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r_amount /= 1000
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r_prefix += 1
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prefix_str = _prefixes_str[r_prefix]
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if prefix_str == "_":
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prefix_str = ""
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return str(r_amount) + " " + prefix_str + self.unit.name
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else:
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return str(r_amount) + " " + self.unit.name
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# mul/div
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def __mul__(self, other):
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if isinstance(other, Quantity):
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return NotImplemented
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return Quantity(self.amount*other, self.unit)
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def __rmul__(self, other):
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if isinstance(other, Quantity):
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return NotImplemented
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return Quantity(other*self.amount, self.unit)
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def __truediv__(self, other):
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if isinstance(other, Quantity):
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if other.unit == self.unit:
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return self.amount/other.amount
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else:
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return NotImplemented
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else:
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return Quantity(self.amount/other, self.unit)
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def __floordiv__(self, other):
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if isinstance(other, Quantity):
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if other.unit == self.unit:
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return self.amount//other.amount
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else:
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return NotImplemented
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else:
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return Quantity(self.amount//other, self.unit)
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# unary ops
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def __neg__(self):
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return Quantity(-self.amount, self.unit)
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def __pos__(self):
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return Quantity(self.amount, self.unit)
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# add/sub
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def __add__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return Quantity(self.amount + other.amount, self.unit)
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def __radd__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return Quantity(other.amount + self.amount, self.unit)
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def __sub__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return Quantity(self.amount - other.amount, self.unit)
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def __rsub__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return Quantity(other.amount - self.amount, self.unit)
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# comparisons
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def __lt__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return self.amount < other.amount
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def __le__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return self.amount <= other.amount
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def __eq__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return self.amount == other.amount
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def __ne__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return self.amount != other.amount
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def __gt__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return self.amount > other.amount
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def __ge__(self, other):
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if self.unit != other.unit:
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raise DimensionError
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return self.amount >= other.amount
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def _register_unit(name, prefixes):
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unit = Unit(name)
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globals()[name+"_unit"] = unit
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amount = _smallest_prefix
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for prefix in _prefixes_str:
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if prefix in prefixes:
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quantity = Quantity(amount, unit)
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full_name = prefix + name if prefix != "_" else name
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globals()[full_name] = quantity
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amount *= 1000
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_register_unit("s", "pnum_")
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_register_unit("Hz", "_kMG")
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microcycle_unit = Unit("microcycle")
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microcycle = Quantity(1, microcycle_unit)
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