refactor Unit
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James Turk
parent
a93cc51188
commit
9211b27415
@ -1,58 +1,59 @@
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from .units import Mass
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from .units import Unit
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from .units import UnitValue as V
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def test_unit_basics():
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assert Unit('kg') == Unit(['kg'])
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assert Unit(['kg'], ['m']) == Unit(['kg'], ['m'])
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def test_basic_conversions():
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a = Mass(2, 'kg')
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a = V(2, 'kg')
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kg = a.as_unit('kg')
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assert kg.scalar == 2
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assert kg.unit == 'kg'
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assert kg.unit == Unit('kg')
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lb = a.as_unit('lb')
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assert abs(lb.scalar - 4.40925) < 0.0001
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assert lb.unit == 'lb'
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assert lb.unit == Unit('lb')
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g = a.as_unit('g')
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assert abs(g.scalar - 2000) < 0.0001
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assert g.unit == 'g'
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assert g.unit == Unit('g')
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assert g.as_unit('lb').scalar == a.as_unit('lb').scalar
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def test_complex_conversion():
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a = Mass(2, ['kg', 'kg'])
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b = a.as_unit('lb')
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def test_basic_cmp():
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assert Mass(1, 'kg') < Mass(2, 'kg')
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assert Mass(1, 'kg') <= Mass(2, 'kg')
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assert Mass(2, 'kg') <= Mass(2, 'kg')
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assert Mass(2, 'kg') == Mass(2, 'kg')
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assert Mass(2, 'kg') >= Mass(2, 'kg')
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assert Mass(2, 'kg') > Mass(1, 'kg')
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assert Mass(2, 'kg') >= Mass(1, 'kg')
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assert V(1, 'kg') < V(2, 'kg')
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assert V(1, 'kg') <= V(2, 'kg')
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assert V(2, 'kg') <= V(2, 'kg')
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assert V(2, 'kg') == V(2, 'kg')
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assert V(2, 'kg') >= V(2, 'kg')
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assert V(2, 'kg') > V(1, 'kg')
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assert V(2, 'kg') >= V(1, 'kg')
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def test_conversion_cmp():
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assert Mass(1, 'kg') < Mass(100, 'lb')
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assert Mass(1000000, 'g') > Mass(100, 'lb')
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assert V(1, 'kg') < V(100, 'lb')
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assert V(1000000, 'g') > V(100, 'lb')
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def test_addition():
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assert Mass(1, 'kg') + Mass(2, 'kg') == Mass(3, 'kg')
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assert Mass(1, 'kg') + Mass(1, 'lb') > Mass(1.4, 'kg')
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assert V(1, 'kg') + V(2, 'kg') == V(3, 'kg')
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assert V(1, 'kg') + V(1, 'lb') > V(1.4, 'kg')
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def test_subtraction():
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assert Mass(2, 'kg') - Mass(1, 'kg') == Mass(1, 'kg')
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assert Mass(1, 'kg') - Mass(1, 'lb') < Mass(0.55, 'kg')
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assert V(2, 'kg') - V(1, 'kg') == V(1, 'kg')
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assert V(1, 'kg') - V(1, 'lb') < V(0.55, 'kg')
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def test_multiplication():
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assert Mass(2, 'kg') * 2 == Mass(4, 'kg')
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assert Mass(2, 'kg') * Mass(1, 'kg') == Mass(2, ['kg', 'kg'])
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assert V(2, 'kg') * 2 == V(4, 'kg')
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assert V(2, 'kg') * V(1, 'kg') == V(2, ['kg', 'kg'])
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def test_division():
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assert Mass(8, 'kg') / 2 == Mass(4, 'kg')
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assert Mass(2, 'kg') / Mass(1, 'kg') == Mass(2, [])
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assert V(8, 'kg') / 2 == V(4, 'kg')
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assert V(2, 'kg') / V(1, 'kg') == V(2, [])
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112
bia/units.py
112
bia/units.py
@ -1,6 +1,16 @@
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from collections import defaultdict
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_UNITS = {
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# mass
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'kg': {'base': 'kg', 'scale': 1.0},
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'lb': {'base': 'kg', 'scale': 2.20462},
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'g': {'base': 'kg', 'scale': 1000.0},
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'm': {'base': 'm', 'scale': 1.0},
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}
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class UnitError(ValueError):
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pass
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@ -10,39 +20,66 @@ class ConversionError(ValueError):
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class Unit(object):
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_mapping = {}
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def __init__(self, n, unit, denom=None):
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self.scalar = float(n)
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if isinstance(unit, str):
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self.unit_numerator = [unit]
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def __init__(self, numerator, denominator=None):
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if isinstance(numerator, str):
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self.numerator = [numerator]
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else:
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self.unit_numerator = unit
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self.numerator = numerator
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self.denominator = [] if denominator is None else denominator
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for u in self.numerator + self.denominator:
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if u not in _UNITS:
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raise ValueError('invalid unit {}'.format(self))
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self.unit_denominator = [] if denom is None else denom
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self._simplify()
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for u in self.unit_numerator + self.unit_denominator:
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if u not in self._mapping:
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raise ValueError('invalid unit {} for {}'.format(unit, self.__class__.__name__))
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def __str__(self):
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return '*'.join(self.numerator)
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@property
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def unit(self):
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return '*'.join(self.unit_numerator)
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def __repr__(self):
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return 'Unit({!r}, {!r})'.format(self.numerator, self.denominator)
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def __eq__(self, other):
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return self.numerator == other.numerator and self.denominator == other.denominator
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def __mul__(self, other):
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return Unit(self.numerator + other.numerator, self.denominator + other.denominator)
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def __div__(self, other):
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return Unit(self.numerator + other.denominator, self.denominator + other.numerator)
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def _simplify(self):
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for u in list(self.denominator):
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if u in self.numerator:
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self.numerator.remove(u)
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self.denominator.remove(u)
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def conversion_factor(self, other):
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factor = 1
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for u in self.numerator:
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factor /= _UNITS[u]['scale']
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for u in other.numerator:
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factor *= _UNITS[u]['scale']
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return factor
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@staticmethod
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def unit(u):
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if isinstance(u, Unit):
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return u
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else:
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return Unit(u)
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class UnitValue(object):
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def __init__(self, n, unit):
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self.scalar = float(n)
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self.unit = Unit.unit(unit)
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def as_unit(self, unit):
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unit = Unit.unit(unit)
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if self.unit == unit:
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return self.__class__(self.scalar, self.unit)
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try:
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if self.unit == self._base:
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factor = self._mapping[unit]
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else:
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factor = self._mapping[unit] / self._mapping[self.unit]
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except KeyError:
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raise ConversionError('cannot convert from {} to {}'.format(self.unit, unit))
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return self.__class__(self.scalar * factor, unit)
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return self.__class__(self.scalar * self.unit.conversion_factor(unit), unit)
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def __str__(self):
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return '{}{}'.format(self.scalar, self.unit)
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@ -67,36 +104,17 @@ class Unit(object):
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return self.__class__(self.scalar - other.scalar, self.unit)
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def __mul__(self, other):
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if isinstance(other, Unit):
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if isinstance(other, UnitValue):
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if self.unit != other.unit:
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other = other.as_unit(self.unit)
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return self.__class__(self.scalar * other.scalar,
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self.unit_numerator + other.unit_numerator)
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return self.__class__(self.scalar * other.scalar, self.unit * other.unit)
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else:
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return self.__class__(self.scalar * other, self.unit)
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def __div__(self, other):
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if isinstance(other, Unit):
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if isinstance(other, UnitValue):
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if self.unit != other.unit:
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other = other.as_unit(self.unit)
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new_numerator = list(self.unit_numerator)
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new_denominator = list(self.unit_denominator)
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for u in other.unit_numerator:
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if u in new_numerator:
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new_numerator.remove(u)
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else:
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new_denominator.append(u)
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return self.__class__(self.scalar / other.scalar, new_numerator, new_denominator)
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return self.__class__(self.scalar / other.scalar, self.unit / other.unit)
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else:
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return self.__class__(self.scalar / other, self.unit)
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class Mass(Unit):
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_base = 'kg'
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# 1kg ==
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_mapping = {
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'kg': 1.0,
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'lb': 2.20462,
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'g': 1000.0,
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}
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