58 lines
1.8 KiB
Python
58 lines
1.8 KiB
Python
# pyRCV2: Preferential vote counting
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# Copyright © 2020–2021 Lee Yingtong Li (RunasSudo)
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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from pyRCV2.numbers.base import BasePyNum, compatible_types
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import decimal
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_quantize_exp = decimal.Decimal('10') ** -6
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def _fixed_set_dps(dps):
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global _quantize_exp
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_quantize_exp = decimal.Decimal('10') ** -dps
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class Fixed(BasePyNum):
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"""
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Wrapper for Python Decimal (for fixed-point arithmetic)
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"""
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_py_class = decimal.Decimal # For BasePyNum
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ROUND_DOWN = decimal.ROUND_DOWN
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ROUND_HALF_UP = decimal.ROUND_HALF_UP
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ROUND_HALF_EVEN = decimal.ROUND_HALF_EVEN
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ROUND_UP = decimal.ROUND_UP
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@classmethod
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def _to_impl(cls, value):
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"""Overrides BasePyNum._to_impl"""
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return decimal.Decimal(value).quantize(_quantize_exp)
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@classmethod
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def _truediv_impl(cls, i1, i2):
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"""Implements BaseNum._truediv_impl"""
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return (i1 / i2).quantize(_quantize_exp)
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@compatible_types
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def __itruediv__(self, other):
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"""Overrides BaseNum.__itruediv__"""
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self.impl = (self.impl / other.impl).quantize(_quantize_exp)
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return self
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def round(self, dps, mode):
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"""Implements BaseNum.round"""
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return Fixed._from_impl(self.impl.quantize(decimal.Decimal('10') ** -dps, mode))
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