# -*- coding: utf-8 -*-
# Copyright 2018 by Christopher C. Little.
# This file is part of Abydos.
#
# Abydos is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Abydos is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Abydos. If not, see <http://www.gnu.org/licenses/>.
"""abydos.fingerprint._position.
Cisłak & Grabowski's position fingerprint
"""
from __future__ import (
absolute_import,
division,
print_function,
unicode_literals,
)
from ._fingerprint import MOST_COMMON_LETTERS_CG, _Fingerprint
__all__ = ['Position', 'position_fingerprint']
[docs]class Position(_Fingerprint):
"""Position Fingerprint.
Based on the position fingerprint from :cite:`Cislak:2017`.
"""
[docs] def fingerprint(
self,
word,
n_bits=16,
most_common=MOST_COMMON_LETTERS_CG,
bits_per_letter=3,
):
"""Return the position fingerprint.
Parameters
----------
word : str
The word to fingerprint
n_bits : int
Number of bits in the fingerprint returned
most_common : list
The most common tokens in the target language, ordered by frequency
bits_per_letter : int
The bits to assign for letter position
Returns
-------
int
The position fingerprint
Examples
--------
>>> bin(position_fingerprint('hat'))
'0b1110100011111111'
>>> bin(position_fingerprint('niall'))
'0b1111110101110010'
>>> bin(position_fingerprint('colin'))
'0b1111111110010111'
>>> bin(position_fingerprint('atcg'))
'0b1110010001111111'
>>> bin(position_fingerprint('entreatment'))
'0b101011111111'
"""
position = {}
for pos, letter in enumerate(word):
if letter not in position and letter in most_common:
position[letter] = min(pos, 2 ** bits_per_letter - 1)
fingerprint = 0
for letter in most_common:
if n_bits:
fingerprint <<= min(bits_per_letter, n_bits)
if letter in position:
fingerprint += min(position[letter], 2 ** n_bits - 1)
else:
fingerprint += min(
2 ** bits_per_letter - 1, 2 ** n_bits - 1
)
n_bits -= min(bits_per_letter, n_bits)
else:
break
for _ in range(n_bits):
fingerprint <<= 1
fingerprint += 1
return fingerprint
[docs]def position_fingerprint(
word, n_bits=16, most_common=MOST_COMMON_LETTERS_CG, bits_per_letter=3
):
"""Return the position fingerprint.
This is a wrapper for :py:meth:`Position.fingerprint`.
Parameters
----------
word : str
The word to fingerprint
n_bits : int
Number of bits in the fingerprint returned
most_common : list
The most common tokens in the target language, ordered by frequency
bits_per_letter : int
The bits to assign for letter position
Returns
-------
int
The position fingerprint
Examples
--------
>>> bin(position_fingerprint('hat'))
'0b1110100011111111'
>>> bin(position_fingerprint('niall'))
'0b1111110101110010'
>>> bin(position_fingerprint('colin'))
'0b1111111110010111'
>>> bin(position_fingerprint('atcg'))
'0b1110010001111111'
>>> bin(position_fingerprint('entreatment'))
'0b101011111111'
"""
return Position().fingerprint(word, n_bits, most_common, bits_per_letter)
if __name__ == '__main__':
import doctest
doctest.testmod()