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# Copyright 2018-2020 by Christopher C. Little. |
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# This file is part of Abydos. |
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# |
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# Abydos is free software: you can redistribute it and/or modify |
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# it under the terms of the GNU 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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# Abydos 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 General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with Abydos. If not, see <http://www.gnu.org/licenses/>. |
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"""abydos.fingerprint._occurrence_halved. |
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Cisłak & Grabowski's occurrence halved fingerprint |
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""" |
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from typing import Tuple |
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from ._fingerprint import MOST_COMMON_LETTERS_CG, _Fingerprint |
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__all__ = ['OccurrenceHalved'] |
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class OccurrenceHalved(_Fingerprint): |
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"""Occurrence Halved Fingerprint. |
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Based on the occurrence halved fingerprint from :cite:`Cislak:2017`. |
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.. versionadded:: 0.3.6 |
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""" |
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def __init__( |
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self, |
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n_bits: int = 16, |
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most_common: Tuple[str, ...] = MOST_COMMON_LETTERS_CG, |
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) -> None: |
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"""Initialize Count instance. |
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Parameters |
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---------- |
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n_bits : int |
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Number of bits in the fingerprint returned |
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most_common : list |
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The most common tokens in the target language, ordered by frequency |
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.. versionadded:: 0.4.0 |
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""" |
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super(OccurrenceHalved, self).__init__() |
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self._n_bits = n_bits |
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self._most_common = most_common |
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def fingerprint(self, word: str) -> str: |
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"""Return the occurrence halved fingerprint. |
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Based on the occurrence halved fingerprint from :cite:`Cislak:2017`. |
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Parameters |
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---------- |
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word : str |
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The word to fingerprint |
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Returns |
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------- |
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str |
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The occurrence halved fingerprint |
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Examples |
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-------- |
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>>> ohf = OccurrenceHalved() |
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>>> ohf.fingerprint('hat') |
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'0001010000000010' |
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>>> ohf.fingerprint('niall') |
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'0000010010100000' |
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>>> ohf.fingerprint('colin') |
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'0000001001010000' |
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>>> ohf.fingerprint('atcg') |
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'0010100000000000' |
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>>> ohf.fingerprint('entreatment') |
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'1111010000110000' |
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.. versionadded:: 0.3.0 |
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.. versionchanged:: 0.3.6 |
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Encapsulated in class |
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.. versionchanged:: 0.6.0 |
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Changed to return a str and added fingerprint_int method |
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""" |
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return ('{:0' + str(self._n_bits) + 'b}').format( |
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self.fingerprint_int(word) |
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) |
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def fingerprint_int(self, word: str) -> int: |
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"""Return the occurrence halved fingerprint. |
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Based on the occurrence halved fingerprint from :cite:`Cislak:2017`. |
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Parameters |
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---------- |
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word : int |
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The word to fingerprint |
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Returns |
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------- |
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int |
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The occurrence halved fingerprint as an int |
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Examples |
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-------- |
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>>> ohf = OccurrenceHalved() |
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>>> ohf.fingerprint_int('hat') |
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5122 |
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>>> ohf.fingerprint_int('niall') |
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1184 |
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>>> ohf.fingerprint_int('colin') |
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592 |
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>>> ohf.fingerprint_int('atcg') |
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10240 |
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>>> ohf.fingerprint_int('entreatment') |
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62512 |
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.. versionadded:: 0.6.0 |
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""" |
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n_bits = self._n_bits |
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if n_bits % 2: |
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n_bits += 1 |
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w_len = len(word) // 2 |
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w_1 = set(word[:w_len]) |
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w_2 = set(word[w_len:]) |
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fingerprint = 0 |
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for letter in self._most_common: |
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if n_bits: |
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fingerprint <<= 1 |
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if letter in w_1: |
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fingerprint += 1 |
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fingerprint <<= 1 |
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if letter in w_2: |
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fingerprint += 1 |
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n_bits -= 2 |
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else: |
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break |
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if n_bits > 0: |
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fingerprint <<= n_bits |
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return fingerprint |
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if __name__ == '__main__': |
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import doctest |
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doctest.testmod() |
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