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66 lines
2.3 KiB
66 lines
2.3 KiB
6 years ago
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import pint
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class ConverterError(Exception):
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pass
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class Converter(object):
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def __init__(self):
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self.ureg = pint.UnitRegistry(autoconvert_offset_to_baseunit=True)
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self.ureg.define('degreeC = kelvin; offset: 273.15 = °C = C')
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self.ureg.define('degreeF = 5 / 9 * kelvin; offset: 255.372222 = °F = F')
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self.default_units = {
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self.ureg.degC: self.ureg.degreeF,
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self.ureg.degreeC: self.ureg.degreeF,
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self.ureg.degF: self.ureg.degreeC,
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self.ureg.degreeF: self.ureg.degreeC,
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self.ureg.kilometer: self.ureg.mile,
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self.ureg.meter: self.ureg.foot,
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self.ureg.centimeter: self.ureg.inch,
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self.ureg.millimeter: self.ureg.inch,
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self.ureg.mile: self.ureg.kilometer,
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self.ureg.foot: self.ureg.meter,
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self.ureg.inch: self.ureg.millimeter,
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self.ureg.kilogram: self.ureg.pound,
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self.ureg.pound: self.ureg.kilogram,
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self.ureg.ounce: self.ureg.kilogram,
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self.ureg.liter: self.ureg.gallon,
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self.ureg.milliliter: self.ureg.floz,
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self.ureg.gallon: self.ureg.liter,
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self.ureg.floz: self.ureg.milliliter,
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}
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def convert(self, expression, unit=None):
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try:
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q = self.ureg.parse_expression(expression)
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except pint.errors.UndefinedUnitError:
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raise ConverterError('unknown units')
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try:
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q.units
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except AttributeError:
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if unit is not None:
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q = self.ureg.parse_expression(expression + unit)
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unit = None
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else:
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raise ConverterError('unknown units')
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try:
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q.units
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except AttributeError:
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raise ConverterError('unknown units')
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if unit is not None:
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try:
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u = self.ureg.parse_units(unit)
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except pint.errors.UndefinedUnitError:
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raise ConverterError('unknown units')
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else:
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try:
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u = self.default_units[q.units]
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except KeyError:
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raise ConverterError('no target units specified')
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try:
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result = q.to(u)
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except pint.errors.DimensionalityError:
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raise ConverterError('invalid conversion')
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return '{:0.5g~P}'.format(result)
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